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Preliminary Technical Data
FEATURES
Low power, low IF transceiver Frequency bands: 433 MHz to 464 MHz 862 MHz to 928 MHz Data rates supported: 0.3 kbps to 200 kbps, FSK 0.3 kbps to 64 kbps, ASK 2.3 V to 3.6 V power supply Programmable output power: -16 dBm to +13 dBm in 0.3 dBm steps Receiver sensitivity: -117.5 dBm at 1 kbps, FSK -110.5 dBm at 9.6 kbps, FSK -106.5 dBm at 9.6 kbps, ASK Low power consumption: 19 mA in receive mode 22 mA in transmit mode (10 dBm output)
RSET VREG(1:4) ADCIN
High Performance ISM Band FSK/ASK Transceiver IC ADF7020
On-chip VCO and fractional-N PLL On-chip 7-bit ADC and temperature sensor 1 ppm RF output frequency accuracy possible from low cost 100 ppm crystal Digital RSSI Leakage current <1 A in power-down mode 48-lead ultrasmall MLF package (chip scale)
APPLICATIONS
Low cost wireless data transfer Remote control/security systems Wireless metering Keyless entry Home automation Process and building control Wireless voice
FUNCTIONAL BLOCK DIAGRAM
MUXOUT
RLNA
BIAS
LDO(1:4)
OFFSET CORRECTION
TEMP SENSOR
TEST MUX
LNA
RFIN RFINB
IF FILTER GAIN
RSSI
MUX
7-BIT ADC
FSK/ASK DEMODULATOR
DATA SYNCHRONIZER
OFFSET CORRECTION AGC CONTROL
FSK MOD CONTROL GAUSSIAN FILTER - MODULATOR
CE RxCLK
Tx/Rx CONTROL
Tx/Rx DATA CLKOUT
AFC CONTROL
INT/LOCK
PA OUT
DIVIDERS/ MUXING
DIV P
N/N+1
SLE
ASK/OOK MOD CONTROL GAUSSIAN FILTER
SERIAL PORT VCO CP PFD DIV R RING OSC CLK DIV
SDATA IN SDATA OUT SCLK
01975-PrG-001
VCOIN CPOUT
OSC
CLKOUT
Figure 1.
Rev. PrH
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.
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ADF7020 TABLE OF CONTENTS
General Description ......................................................................... 3 Specifications..................................................................................... 4 Timing Characteristics..................................................................... 7 Absolute Maximum Ratings............................................................ 8 ESD Caution.................................................................................. 8 Pin Configuration and Function Descriptions............................. 9 Frequency Synthesizer ................................................................... 11 Reference Input Section............................................................. 11 Choosing Channels for Best System Performance................. 13 Transmitter ...................................................................................... 14 Modulation Schemes.................................................................. 14 Receiver Section.............................................................................. 16 RF Front End............................................................................... 16 RSSI/AGC Section...................................................................... 17 FSK Demodulators on the ADF7020 ....................................... 17 FSK Correlator/Demodulator................................................... 17 Linear FSK Demodulator .......................................................... 19 AFC Section ................................................................................ 19 Automatic Sync Word Recognition.......................................... 20 Applications Section....................................................................... 21 LNA/PA Matching...................................................................... 21 Transmit Protocol and Coding Considerations ..................... 22 Image Rejection Calibration ..................................................... 22
Preliminary Technical Data
Device Programming after Initial Power-Up ......................... 22 Serial Interface ................................................................................ 24 Readback Format........................................................................ 24 Register 0--N Register............................................................... 25 Register 1--Oscillator/Filter Register...................................... 26 Register 2--Transmit Modulation Register (ASK/OOK Mode)........................................................................................... 27 Register 2--Transmit Modulation Register (FSK Mode) ..... 28 Register 2--Transmit Modulation Register (GFSK/GOOK Mode)........................................................................................... 29 Register 3--Receiver Clock Register ....................................... 30 Register 4--Demodulator Setup Register ............................... 31 Register 5--Sync Byte Register................................................. 32 Register 6--Correlator/Demodulator Register ...................... 33 Register 7--Readback Setup Register...................................... 34 Register 8--Power-Down Test Register .................................. 35 Register 9--AGC Register......................................................... 36 Register 10--AGC 2 Register.................................................... 37 Register 11--AFC Register ....................................................... 37 Register 12--Test Register......................................................... 38 Register 13--Offset Removal and Signal Gain Register ....... 39 Outline Dimensions ....................................................................... 40 Ordering Guide .......................................................................... 40
REVISION HISTORY
Revision PrH: Preliminary Version
Rev. PrH | Page 2 of 40
Preliminary Technical Data GENERAL DESCRIPTION
The ADF7020 is a low power, highly integrated FSK/GFSK/ ASK/OOK/GASK transceiver designed for operation in the license-free ISM bands at 433 MHz, 868 MHz, and 915 MHz. It is suitable for circuit applications that meet either the European ETSI-300-220 or the North American FCC (Part 15) regulatory standards. A complete transceiver can be built using a small number of external discrete components, making the ADF7020 very suitable for price-sensitive and area-sensitive applications. The transmit section contains a VCO and low noise fractional-N PLL with output resolution of <1 ppm. The VCO operates at twice the fundamental frequency to reduce spurious emissions and frequency pulling problems. The transmitter output power is programmable in 0.3 dB steps from -16 dBm to +13 dBm. The transceiver RF frequency, channel spacing, and modulation are programmable using a simple 3-wire interface. The device operates with a power supply range of 2.3 V to 3.6 V and can be powered down when not in use.
ADF7020
A low IF architecture is used in the receiver (200 kHz), minimizing power consumption and the external component count and avoiding interference problems at low frequencies. The ADF7020 supports a wide variety of programmable features including Rx linearity, sensitivity, and IF bandwidth, allowing the user to trade off receiver sensitivity and selectivity against current consumption, depending on the application. The receiver also features a patent-pending automatic frequency control (AFC) loop, allowing the PLL to track out the frequency error in the incoming signal. An on-chip ADC provides readback of an integrated temperature sensor, an external analog input, the battery voltage, or the RSSI signal, which provides savings on an ADC in some applications. The temperature sensor is accurate to 5C over the full operating temperature range of -40C to +85C.
Rev. PrH | Page 3 of 40
ADF7020 SPECIFICATIONS
Preliminary Technical Data
VDD = 2.3 V to 3.6 V, GND = 0 V, TA = TMIN to TMAX, unless otherwise noted. Typical specifications are at VDD = 3 V, TA = 25C. All measurements are performed using the test circuit in Figure TBD using PN9 data sequence, unless otherwise noted. Table 1.
Parameter RF CHARACTERISTICS Frequency Ranges Frequency Ranges (Divide-by-2 Mode) Phase Frequency Detector Frequency TRANSMISSION PARAMETERS Data Rate FSK/GFSK Data Rate OOK/ASK Frequency Shift Keying GFSK/FSK Frequency Deviation2, 3 Deviation Frequency Resolution Gaussian Filter BT Adjacent Channel Power, GFSK Min 862 433 RF/256 0.3 0.3 1 4.88 100 0.5 TBD Typ Max 928 464 20 200 641 110 620 Unit MHz MHz MHz kbps kbps kHz kHz Hz dBc PFD = 3.625 MHz PFD = 20 MHz PFD = 3.625 MHz Channel spacing = 25 kHz, measured in adjacent channel 8.5 kHz from center; DR = 4.8 kbps, FDEV = 2.4 kHz, FRF = 868 MHz 868.95 MHz 250 kHz, DR = 38.4 kbps, FDEV = 19.2 kHz Test Conditions
-50 Amplitude Shift Keying ASK Modulation Depth OOK -PA Off Feedthrough Transmit Power4
dBc
30 -50 -20 +13 TBD TBD TBD 13 TBD TBD 0.3125 -57 -55 -65 -27 -21 TBD TBD TBD TBD -18 -18 -35
dB dBm dBm dBm dBm dBm dBm dBm dB dB dBm dBc dBc dBc dBc dBc kHz rms
FRF = 915 MHz, VDD = 3.0 V, TA = 25C FRF = 868 MHz, VDD = 3.0 V, TA = 25C FRF = 433 MHz, VDD = 3.0 V, TA = 25C FRF = 915 MHz, VDD = 3.6 V FRF = 915 MHz, VDD = 3.0 V FRF = 915 MHz, VDD = 2.3 V From 902 MHz to 928 MHz
Transmit Power Variation Highest Power Setting
Transmit Power Flatness Programmable Step Size -20 dBm to +13 dBm Spurious Emissions during PLL Settling Integer Boundary Reference Harmonics Second Harmonic Third Harmonic All Other Harmonics VCO Frequency Pulling, OOK mod Optimum PA Load Impedance5
Mute PA until lock enabled (R2_DB5 =1 ) 50 kHz loop BW
DR = 9.6 kbps FRF = 915 MHz FRF = 868 MHz FRF = 433 MHz At BER = 1E - 3, FRF = 915 MHz DR = 1 kbps, FDEV = 5 kHz DR = 1 kbps, FDEV = 5 kHz
RECEIVER PARAMETERS FSK Input Sensitivity6 High Sensitivity Mode Low Current Mode
See notes at end of table.
-117.5 -TBD
dBm dBm
Rev. PrH | Page 4 of 40
Preliminary Technical Data
Parameter High Sensitivity Mode Low Current Mode High Sensitivity Mode Low Current Mode OOK Input Sensitivity High Sensitivity Mode Low Current Mode High Sensitivity Mode Low Current Mode LNA and Mixer Input IP37 Enhanced Linearity Mode Low Current Mode High Sensitivity Mode Rx Spurious Emissions8 AFC Pull-In Range Response time Accuracy Channel Filtering Adjacent Channel Rejection (Offset = 1 x IF Filter BW Setting) Second Adjacent Channel Rejection (Offset = 2 x IF Filter BW Setting) Third Adjacent Channel Rejection (Offset = 3 x IF Filter BW Setting) Image Channel Rejection (Image Channel = FRF - 400 kHz) Co-channel Rejection Wide-Band Interference Rejection Saturation (Maximum Input Level) Input Impedance Min Typ -110.5 -104 -99 -TBD -TBD -TBD -106.5 -TBD Max Unit dBm dBm dBm dBm dBm dBm dBm dBm
ADF7020
Test Conditions DR = 9.6 kbps, FDEV = 10 kHz DR = 9.6 kbps, FDEV = 10 kHz DR = 200 kbps, FDEV = 50 kHz DR = 200 kbps, FDEV = 50 kHz At BER = 1E - 3, FRF = 915 MHz DR = 1 kbps DR = 1 kbps DR = 9.6 kbps DR = 9.6 kbps
6.8 -3.2 -35 -57 -47 50 1 27 50 TBD 30 TBD -3 TBD 12 TBD TBD TBD -100 to -36 3 TBD 350 TBD TBD
dBm dBm dBm dBm dBm kHz Bits kHz dB dB dB dB dB dB dB dBm dBm dB dB s
Pin = -20 dBm, 2 CW interferers FRF = 915 MHz, f1 = FRF + 3 MHz F2 = FRF + 6 MHz, maximum gain <1 GHz at antenna input >1 GHz at antenna input IF_BW = 200 kHz
IF filter BW settings = 100 kHz, 150 kHz, 200 kHz Desired signal 3 dB above the input sensitivity level, CW interferer power level increased until BER = 10-3, image channel excluded Uncalibrated Calibrated9 Swept from 100 MHz to 2 GHz, measured as channel rejection FSK mode, BER = 10-3 FRF = 915 MHz, RFIN, RFIN to GND FRF = 868 MHz FRF = 433 MHz
RSSI Range at Input Linearity Absolute Accuracy Response Time PHASE LOCKED LOOP VCO Gain
Maximum input step change, AGC included, RSSI ready for readback 902 MHz to 928 MHz band., VCO adjust = 0 860MHz to 870 MHz band, VCO Adjust = 0 At 433MHz, VCO Adjust = 0 PA = 0 dBm, VDD = 3.0 V, PFD = 10 MHz, FRF = 915 MHz, VCO BIAS = 4 At 1 MHz offset From 300 Hz to 5 kHz
65 130 TBD -92 -110 TBD
MHz/V MHz/V MHz/V dBc/Hz dBc/Hz Hz
Phase Noise (In-Band) Phase Noise (Out-of-Band) Residual FM
See notes at end of table.
Rev. PrH | Page 5 of 40
ADF7020
Parameter PLL Settling Time Min Typ 40 Max Unit s
Preliminary Technical Data
Test Conditions Measured for a 10 MHz frequency step to within 5 ppm accuracy, PFD = 20 MHz, LBW = TBD
REFERENCE INPUT Crystal Reference External Oscillator Load capacitance Input Level TIMING INFORMATION Chip Enabled to Regulator Ready Crystal Oscillator Startup time Tx to Rx Turnaround Time LOGIC INPUTS VINH, Input High Voltage VINL, Input Low Voltage IINH/IINL, Input Current CIN, Input Capacitance Control Clock Input LOGIC OUTPUTS VOH,Output High Voltage VOL, Output Low Voltage CLKOUT Rise/Fall CLKOUT Load TEMPERATURE RANGE--TA POWER SUPPLIES Voltage Supply AVDD DVDD Transmit Current Consumption -20 dBm -10 dBm 0 dBm 10 dBm Receive Current Consumption Low Current Mode High Sensitivity Mode Power-Down Mode Low Power Sleep Mode
3.625 3.625 TBD
24 24
MHz MHz pF CMOS levels s ms
See the Reference Input Section
TBD 1 350 s + (5 x TBIT) 0.7 x V DD 0.2 x V DD 1 10 50 DVDD - 0.4 0.4 5 10 +85
CREG = 100 nF With 19.2 MHz XTAL Time to synchronized data, includes AGC settling
V V A pF MHz V V ns pF C IOH = 500 A IOL = 500 A
-40
2.3 AVDD
3.6 AVDD
V FRF = 915 MHz, VDD = 3.0 V, PA is matched in to 50
TBD 12 15 22 19 21 0.1 TBD TBD 1
mA mA mA mA mA mA A
VCO_BIAS_SETTING = 3
1 2
Higher data rates are achievable depending on local regulations. For definition of frequency deviation, see the Register 2--Transmit Modulation Register (FSK Mode) section. 3 For definition of GFSK frequency deviation, see the Register 2--Transmit Modulation Register (GFSK/GOOK Mode) section. 4 Measured as maximum unmodulated power. Output power varies with both supply and temperature. 5 For matching details, see the LNA/PA Matching section. 6 See Table 5 for description of different receiver modes. 7 See Table 5 for description of different receiver modes. 8 Follow the matching and layout guidelines to achieve the relevant FCC/ETSI specifications. 9 See the Image Rejection Calibration section.
Rev. PrH | Page 6 of 40
Preliminary Technical Data TIMING CHARACTERISTICS
VDD = 3 V 10%; VGND = 0 V, TA = 25C, unless otherwise noted. Guaranteed by design, but not production tested. Table 2.
Parameter t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 Limit at TMIN to TMAX <10 <10 <25 <25 <10 <20 ADF7020
t3
SCLK
t4
t1
t2
DB1 (CONTROL BIT C2) DB0 (LSB) (CONTROL BIT C1)
SDATA
DB31 (MSB)
DB30
DB2
t6
SLE
01975-PrG-002
t5
Figure 2. Serial Interface Timing Diagram
t1
SCLK
t2
SDATA REG7 DB0 (CONTROL BIT C1) SLE
t3
t10
X RV16 RV15 RV2 RV1
01975-PrG-003
SREAD
t8
t9
Figure 3. Readback Timing Diagram
Rev. PrH | Page 7 of 40
ADF7020 ABSOLUTE MAXIMUM RATINGS
TA = 25C, unless otherwise noted. Table 3.
Parameter VDD to GND1 Analog I/O Voltage to GND Digital I/O Voltage to GND Operating Temperature Range Industrial (B Version) Storage Temperature Range Maximum Junction Temperature MLF JA Thermal Impedance Lead Temperature Soldering Vapor Phase (60 s) Infrared (15 s) Rating -0.3 V to +5 V -0.3 V to AVDD + 0.3 V -0.3 V to DVDD + 0.3 V -40C to +85C -65C to +125C 125C TBDC/W 235C 240C
Preliminary Technical Data
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. This device is a high-performance RF integrated circuit with an ESD rating of <2 kV and it is ESD sensitive. Proper precautions should be taken for handling and assembly.
1
GND = CPGND = RFGND = DGND = AGND = 0 V.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
Rev. PrH | Page 8 of 40
Preliminary Technical Data PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
VCO GND
48 47 46 45 44 43 42 41 40 39 38 37
ADF7020
VCOIN VREG1 VDD1 RFOUT RFGND RFIN RFINB RLNA VDD4
1 2 3 4 5 6 7 8 9
PIN 1 INDICATOR
MUXOUT
CPOUT
VREG3
CVCO
GND1
OSC1
OSC2
VDD3
GND
GND
VDD
36 35 34 33 32
CLKOUT DATA CLK DATA I/O INT/LOCK VDD2 VREG2 ADCIN GND2 SCLK SREAD SDATA SLE
ADF7020
TOP VIEW (Not to Scale)
31 30 29 28 27 26 25
RSET 10 VREG4 11 GND4 12
MIX_I 13 MIX_I 14 MIX_Q 15 MIX_Q 16 FILT_I 17 FILT_I 18 GND4 19 FILT_Q 20 FILT_Q 21 GND4 22 TEST_A 23 CE 24
Figure 4. Pin Configuration
Table 4. Pin Function Descriptions
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13-18 19, 22 20, 21, 23 24 25 26 27 28 Mnemonic VCOIN VREG1 VDD1 RFOUT RFGND RFIN RFINB RLNA VDD4 RSET VREG4 GND4 MIX/FILT GND4 FILT/TEST_A CE SLE SDATA SREAD SCLK Function The tuning voltage on this pin determines the output frequency of the voltage controlled oscillator (VCO). The higher the tuning voltage, the higher the output frequency. Regulator Voltage for PA Block. A 100 nF capacitor should be placed between this pin and ground for regulator stability and noise rejection. Voltage Supply for PA Block. Decoupling capacitors (X7R or Tantalum) of 0.1 F and 0.01 F should be placed as close as possible to this pin. The modulated signal is available at this pin. Output power levels are from -20 dBm to +13 dBm. The output should be impedance matched to the desired load using suitable components. See the Transmitter section. Ground for Output Stage of Transmitter. LNA Input for Receiver Section. Input matching is required between the antenna and the differential LNA input to ensure maximum power transfer. See the LNA/PA Matching section. Complementary LNA Input. See the LNA/PA Matching section. External bias resistor for LNA. Optimum resistor is 1.1 k with 5% tolerance. Voltage supply for LNA/MIXER block. This pin should be decoupled to ground with a 0.01 F capacitor. External Resistor to Set Charge Pump Current and Some Internal Bias Currents. Use 3.6 k with 5% tolerance. Regulator Voltage for LNA/MIXER block. A 100 nF capacitor should be placed between this pin and GND for regulator stability and noise rejection. Ground for LNA/MIXER block. Signal Chain Test Pins. These pins are high impedance under normal conditions and should be left unconnected. Ground for LNA/MIXER block. Signal Chain Test Pins. These pins are high impedance under normal conditions and should be left unconnected. Chip Enable. Bringing CE low puts the ADF7020 into complete power-down. Register values are lost when CE is low, and the part must be reprogrammed once CE is brought high. Load Enable, CMOS Input. When LE goes high, the data stored in the shift registers is loaded into one of the four latches. A latch is selected using the control bits. Serial Data Input. The serial data is loaded MSB first with the two LSBs as the control bits. This pin is a high impedance CMOS input. Serial Data Output. This pin is used to feed readback data from the ADF7020 to the microcontroller. The SCLK input is used to clock each readback bit (AFC, ADC readback) from the SREAD pin. Serial Clock Input. This serial clock is used to clock in the serial data to the registers. The data is latched into the 24-bit shift register on the CLK rising edge. This pin is a digital CMOS input.
Rev. PrH | Page 9 of 40
01975-PrG-004
ADF7020
Pin No. 29 30 31 32 33 Mnemonic GND2 ADCIN VREG2 VDD2 INT/LOCK
Preliminary Technical Data
Function Ground for Digital Section. Analog-to-Digital Converter Input. The internal 7-bit ADC can be accessed through this pin. Full scale is 0 to 1.9 V. Readback is made using the SREAD pin. Regulator Voltage for Digital Block. A 100 nF capacitor should be placed between this pin and ground for regulator stability and noise rejection. Voltage Supply for Digital Block. A decoupling capacitor (X7R or Tantalum) of 0.01 F should be placed as close as possible to this pin. Bidirectional Pin. In output mode (INTerrupt mode), the ADF7020 asserts the INT/ LOCK pin when it has found a match for the preamble sequence. In input mode (lock mode), the microcontroller can be used to lock the demodulator threshold when a valid preamble has been detected. Once the threshold is locked, NRZ data can be reliably received. In this mode, a demod lock can be asserted with minimum delay. Transmit Data Input/Received Data Output. This is a digital pin and normal CMOS levels apply. In receive mode, the pin outputs the synchronized data clock. The positive clock edge is matched to the center of the received data. In GFSK transmit mode, the pin outputs an accurate clock to latch the data from the microcontroller into the transmit section at the exact required data rate. See the Gaussian Frequency Shift Keying (GFSK) section. A Divided-Down Version of the Crystal Reference with Output Driver. The digital clock output can be used to drive several other CMOS inputs such as a microcontroller clock. The output has a 50:50 mark-space ratio. This pin provides the Lock_Detect signal, which is used to determine if the PLL is locked to the correct frequency. Other signals include Regulator_Ready, which is an indicator of the status of the serial interface regulator. The reference crystal should be connected between this pin and OSC1. A TCXO reference can be used by driving this pin with CMOS levels and disabling the crystal oscillator. The reference crystal should be connected between this pin and OSC2. Voltage Supply for the Charge Pump and PLL Dividers. This pin should be decoupled to ground with a 0.01 F capacitor. Regulator Voltage for Charge Pump and PLL Dividers. A 100 nF capacitor should be placed between this pin and ground for regulator stability and noise rejection. Charge Pump Output. This output generates current pulses that are integrated in the loop filter. The integrated current changes the control voltage on the input to the VCO. Voltage Supply for VCO Tank Circuit. This pin should be decoupled to ground with a 0.01 F capacitor. Grounds for VCO Block. A 22 nF capacitor should be placed between this pin and VREG1 to reduce VCO noise.
34 35
DATA I/O DATA CLK
36 37
CLKOUT MUXOUT
38 39 40 41 42 43 44-47 48
OSC2 OSC1 VDD3 VREG3 CPOUT VDD GND CVCO
Rev. PrH | Page 10 of 40
Preliminary Technical Data FREQUENCY SYNTHESIZER
REFERENCE INPUT SECTION
The on-board crystal oscillator circuitry (Figure 5) can use an inexpensive quartz crystal as the PLL reference. The oscillator circuit is enabled by setting R1_DB12 high. It is enabled by default on power-up and is disabled by bringing CE low. Errors in the crystal can be corrected using the automatic frequency control (see the AFC Section) feature or by adjusting the fractional-N value (see the N Counter section). A single-ended reference (TCXO, CXO) can also be used. The CMOS levels should be applied to OSC2 with R1_DB12 set low.
ADF7020
R Counter The 3-bit R counter divides the reference input frequency by an integer from 1 to 7. The divided-down signal is presented as the reference clock to the phase frequency detector (PFD). The divide ratio is set in Register 1. Maximizing the PFD frequency reduces the N value. This reduces the noise multiplied at a rate of 20 log(N) to the output, as well as reducing occurrences of spurious components. The R Register defaults to R = 1 on power-up: PFD [Hz] = XTAL/R MUXOUT and Lock Detect
01975-PrG-005
OSC1
CP2
OSC2 CP1
The MUXOUT pin allows the user to access various digital points in the ADF7020. The state of MUXOUT is controlled by Bits R0_DB(29:31). Regulator Ready REGULATOR READY is the default setting on MUXOUT after the transceiver has been powered up. The power-up time of the regulator is typically 50 s. Because the serial interface is powered from the regulator, the regulator must be at its nominal voltage before the ADF7020 can be programmed. The status of the regulator can be monitored at MUXOUT. When the REGULATOR READY signal on MUXOUT is high, programming of the ADF7020 can begin.
DVDD
Figure 5. Oscillator Circuit on the ADF7020
Two parallel resonant capacitors are required for oscillation at the correct frequency; their values are dependent on the crystal specification. They should be chosen so that the series value of capacitance added to the PCB track capacitance adds up to the load capacitance of the crystal, usually 20 pF. Track capacitance values vary from 2 pF to 5 pF, depending on board layout. Where possible, choose capacitors that have a very low temperature coefficient to ensure stable frequency operation over all conditions. CLKOUT Divider and Buffer The CLKOUT circuit takes the reference clock signal from the oscillator section, shown in Figure 5, and supplies a divideddown 50:50 mark-space signal to the CLKOUT pin. An even divide from 2 to 30 is available. This divide number is set in R1_DB(8:11). On power-up, the CLKOUT defaults to divide-by-8.
DVDD CLKOUT ENABLE BIT
REGULATOR READY DIGITAL LOCK DETECT ANALOG LOCK DETECT R COUNTER OUTPUT N COUNTER OUTPUT PLL TEST MODES - TEST MODES
01975-PrG-007
MUX
CONTROL
MUXOUT
DGND
OSC1
/2
CLKOUT
01975-PrG-006
DIVIDER 1 TO 15
Figure 7. MUXOUT Circuit
Digital Lock Detect Digital lock detect is active high. The lock detect circuit is located at the PFD. When the phase error on five consecutive cycles is less than 15 ns, lock detect is set high. Lock detect remains high until 25 ns phase error is detected at the PFD. Because no external components are needed for digital lock detect, it is more widely used than analog lock detect.
Figure 6. CLKOUT Stage
To disable CLKOUT, set the divide number to 0. The output buffer can drive up to a 20 pF load with a 10% rise time at 4.8 MHz. Faster edges can result in some spurious feedthrough to the output. A small series resistor (50 ) can be used to slow the clock edges to reduce these spurs at FCLK.
Rev. PrH | Page 11 of 40
ADF7020
Analog Lock Detect This N-channel open-drain lock detect should be operated with an external pull-up resistor of 10 k nominal. When a lock has been detected, this output is high with narrow low-going pulses. Voltage Regulators The ADF7020 contains four regulators to supply stable voltages to the part. The nominal regulator voltage is 2.3 V. Each regulator should have a 100 nF capacitor connected between VREG and GND. When CE is high, the regulators and other associated circuitry are powered on, drawing a total supply current of 2 mA. Bringing the chip-enable pin low disables the regulators, reduces the supply current to less than 1 A, and erases all values held in the registers. The serial interface operates off a regulator supply; therefore, to write to the part, the user must have CE high and the regulator voltage must be stabilized. Regulator status (VREG4) can be monitored using the regulator ready signal from MUXOUT. Loop Filter The loop filter integrates the current pulses from the charge pump to form a voltage that tunes the output of the VCO to the desired frequency. It also attenuates spurious levels generated by the PLL. A typical loop filter design is shown in Figure 8.
Preliminary Technical Data
For GFSK, it is recommended that an LBW of 2.0 to 2.5 times the data rate be used to ensure that sufficient samples are taken of the input data while filtering system noise. The free design tool ADIsimPLL can be used to design loop filters for the ADF7020.
N Counter
The feedback divider in the ADF7020 PLL consists of an 8-bit integer counter and a 14-bit - fractional-N divider. The integer counter is the standard pulse-swallow type common in PLLs. This sets the minimum integer divide value to 31. The fractional divide value gives very fine resolution at the output, where the output frequency of the PLL is calculated as FOUT =
Fractional-N XTAL x (Integer-N + ) R 214
REFERENCE IN 4R PFD/ CHARGE PUMP VCO
4N
FRACTIONAL-N
INTEGER-N
01975-PrG-008
CHARGE PUMP OUT
Figure 9. Fractional-N PLL
VCO
The combination of the integer-N (maximum = 255) and the fractional-N (maximum = 16383/16384) give a maximum N divider of 255 + 1. Therefore, the minimum usable PFD is PDFMIN [Hz] = Maximum Required Output Frequency/(255 + 1) For example, when operating in the European 868 MHz to 870 MHz band, PFDMIN equals 3.4 MHz.
Voltage Controlled Oscillator (VCO)
Figure 8. Typical Loop Filter Configuration
In FSK, the loop should be designed so that the loop bandwidth (LBW) is approximately five times the data rate. Widening the LBW excessively reduces the time spent jumping between frequencies, but can cause insufficient spurious attenuation. For ASK systems, a wider LBW is recommended. The sudden large transition between two power levels might result in VCO pulling and can cause a wider output spectrum than is desired. By widening the LBW to more than 10 times the data rate, the amount of VCO pulling is reduced, because the loop settles quickly back to the correct frequency. The wider LBW might restrict the output power and data rate of ASK-based systems compared with FSK-based systems. Narrow-loop bandwidths can result in the loop taking long periods of time to attain lock. Careful design of the loop filter is critical to obtaining accurate FSK/GFSK modulation.
To minimize spurious emissions, the on-chip VCO operates from 1732 MHz to 1856 MHz. The VCO signal is then divided by 2 to give the required frequency for the transmitter and the required LO frequency for the receiver. The VCO should be recentered, depending on the required frequency of operation, by programming the VCO adjust bits R1_DB(20:21). The VCO is enabled as part of the PLL by the PLL-enable bit, R0_DB28. A further frequency divide-by-2 is included to allow operation in the lower 433 MHz and 460 MHz bands. To enable operation in the these bands, R1_DB13 should be set to 1. The VCO needs an external 22 nF between the VCO and the regulator to reduce internal noise.
Rev. PrH | Page 12 of 40
01975-PrG-009
THIRD-ORDER - MODULATOR
Preliminary Technical Data
VCO Bias Current
ADF7020
CHOOSING CHANNELS FOR BEST SYSTEM PERFORMANCE
The fractional-N PLL allows the selection of any channel within 868 MHz to 928 MHz (and 433MHz using divide-by-2) to a resolution of <100 Hz. This also facilitates frequency hopping systems. Careful selection of the RF transmit channels must be made to achieve best spurious performance. The architecture of fractional-N results in some level of the nearest integer channel moving through the loop to the RF output. These "beat-note" spurs are not attenuated by the loop, if the desired RF channel and the nearest integer channel are separated by a frequency of less than the LBW. The occurrence of beat-note spurs is rare, because the integer frequencies are at multiples of the reference, which is typically >10 MHz. Beat-note spurs can be significantly reduced in amplitude by avoiding very small or very large values in the fractional register, using the frequency doubler. By having a channel 1 MHz away from an integer frequency, a 100 kHz loop filter can reduce the level to <-45 dBc. When using an external VCO, the fast lock (bleed) function reduces the spurs to <-60 dBc for the same conditions.
VCO bias current can be adjusted using Bits R1_DB19 to R1_DB16. To ensure VCO oscillation, the minimum bias current setting under typical conditions is 2.5 mA.
VCO BIAS R1_DB (16:19) TO PA AND N DIVIDER LOOP FILTER VCO /2 /2 MUX
220F
01975-PrG-010
CVCO PIN
VCO SELECT BIT
Figure 10. Voltage Controlled Oscillator (VCO)
Rev. PrH | Page 13 of 40
ADF7020 TRANSMITTER
RF OUTPUT STAGE
The PA of the ADF7020 is based on a single-ended, controlled current, open-drain amplifier that has been designed to deliver up to 13 dBm into a 50 load at a maximum frequency of 928 MHz. The PA output current and, consequently, the output power are programmable over a wide range. The PA configurations in FSK/GFSK and ASK/OOK modulation modes are shown in Figure 11 and Figure 12, respectively. In FSK/GFSK modulation mode, the output power is independent of the state of the DATA_IO pin. In ASK/OOK modulation mode, it is dependent on the state of the DATA_IO pin and Bit R2_DB29, which selects the polarity of the TxData input. For each transmission mode, the output power can be adjusted as follows:
* *
Preliminary Technical Data
The PA is equipped with overvoltage protection, which makes it robust in severe mismatch conditions. Depending on the application, one can design a matching network for the PA to exhibit optimum efficiency at the desired radiated output power level for a wide range of different antennas, such as loop or monopole antennas. See the LNA/PA Matching section for details.
PA Bias Currents and Mute PA until Lock Bit
Control Bits R2_DB(30:31) facilitate an adjustment of the PA bias current to further extend the output power control range, if necessary. If this feature is not required, the default value of 7 A is recommended. The output stage is powered down by resetting Bit R2_DB4. To reduce the level of undesired spurious emissions, the PA can be muted during the PLL lock phase by setting Bit R2_DB5 (mute PA until lock bit).
FSK/GFSK: The output power is set using bits R2_DB(9:14). ASK: The output power for the inactive state of the TxData input is set by Bits R2_DB(15:20). The output power for the active state of the TxData input is set by Bits R2_DB(9:14). OOK: The output power for the active state of the TxData input is set by Bits R2_DB(9:14). The PA is muted when the TxData input is inactive.
R2_DB(30:31) 2 6
MODULATION SCHEMES
Frequency Shift Keying (FSK)
*
Frequency shift keying is implemented by setting the N value for the center frequency and then toggling this with the TxData line. The deviation from the center frequency is set using Bits R2_DB(15:23). The deviation from the center frequency in Hz is
FSK DEVIATION [Hz] = PFD x Modulation Number 214
IDAC
R2_DB(9:14)
where Modulation Number is a number from 1 to 511 (R2_DB(15:23)) . Select FSK using Bits R2_DB(6:8).
RFOUT R2_DB4 + R2_DB5
01975-PrG-011
RFGND FROM VCO
DIGITAL LOCK DETECT
4R
Figure 11. PA Configuration in FSK/GFSK Mode
DATA I/O R2_DB29 R2_DB(30:31) 6 IDAC 6 6 RFOUT + 0 R2_DB4 R2_DB5
01975-PrG-012
PFD/ CHARGE PUMP
PA STAGE VCO
ASK/OOK MODE
FSK DEVIATION FREQUENCY /N -FDEV +FDEV
R2_DB(9:14) R2_DB(15:23)
TxDATA FRACTIONAL-N INTEGER-N
Figure 13. FSK Implementation
RFGND FROM VCO
DIGITAL LOCK DETECT
Figure 12. PA Configuration in ASK/OOK Mode
Rev. PrH | Page 14 of 40
01975-PrG-013
THIRD-ORDER - MODULATOR
Preliminary Technical Data
Gaussian Frequency Shift Keying (GFSK)
Gaussian frequency shift keying reduces the bandwidth occupied by the transmitted spectrum by digitally prefiltering the TxData. A TxCLK output line is provided from the ADF7020 for synchronization of TxData from the microcontroller. The TxCLK line can be connected to the clock input of a shift register that clocks data to the transmitter at the exact data rate.
ADF7020
Amplitude Shift Keying (ASK)
Amplitude shift keying is implemented by switching the output stage between two discrete power levels. This is accomplished by toggling the DAC, which controls the output level between two 6-bit values set up in Register 2. A zero TxData bit sends Bits R2_DB(15:20) to the DAC. A high TxData bit sends Bits R2_DB(9:14) to the DAC. A maximum modulation depth of 30 dB is possible.
Setting Up the ADF7020 for GFSK
To set up the frequency deviation, set the PFD and the mod control bits:
On-Off Keying (OOK)
On-off keying is implemented by switching the output stage to a certain power level for a high TxData bit and switching the output stage off for a zero. For OOK, the transmitted power for a high input is programmed using Bits R2_DB(9:14).
GFSK DEVIATION [Hz] =
PFD x 2 m 212
Gaussian On-Off Keying (G-OOK)
Gaussian on-off keying represents a prefiltered form of OOK modulation. The usually sharp symbol transitions are replaced with smooth Gaussian filtered transitions, the result being a reduction in frequency pulling of the VCO. Frequency pulling of the VCO in OOK mode can lead to a wider than desired BW, especially if it is not possible to increase the loop filter BW > 300 kHz. The G-OOK sampling clock samples data at the data rate. (See the Setting Up the ADF7020 for GFSK section.)
where m is GFSK_MOD_CONTROL set using R2_DB(24:26). To set up the GFSK data rate:
DR [bps] = PFD DIVIDER _ FACTOR x INDEX _ COUNTER
For further information, see the application note, Using GFSK on the ADF7010, in the EVAL-ADF7010EB1 Technical Note.
Rev. PrH | Page 15 of 40
ADF7020 RECEIVER SECTION
RF FRONT END
The ADF7020 is based on a fully integrated, low IF receiver architecture. The low IF architecture facilitates a very low external component count and does not suffer from power-lineinduced interference problems. Figure 14 shows the structure of the receiver front end. The many programming options allow users to trade off sensitivity, linearity, and current consumption against each other in the way best suitable for their applications. To achieve a high level of resilience against spurious reception, the LNA features a differential input. Switch SW2 shorts the LNA input when transmit mode is selected (R0_DB27 = 0). This feature facilitates the design of a combined LNA/PA matching network, avoiding the need for an external Rx/Tx switch. See the LNA/PA Matching section for details on the design of the matching network.
I (TO FILTER) RFIN Tx/Rx SELECT [R0_DB27] RFINB LNA MODE [R6_DB15] LNA CURRENT [R6_DB(16:17)] LNA GAIN [R9_DB(20:21)] LNA/MIXER ENABLE [R8_DB6]
Preliminary Technical Data
Based on the specific sensitivity and linearity requirements of the application, it is recommended to adjust control bits LNA_mode (R6_DB15) and mixer_linearity (R6_DB18) as outlined in Table 5. The gain of the LNA is configured by the LNA_gain field, R9_DB(20:21), and can be set by either the user or the AGC logic.
IF Filter Settings/Calibration
Out-of-band interference is rejected by means of a fourth-order Butterworth polyphase IF filter centered around a frequency of 200 kHz. The bandwidth of the IF filter can be programmed between 100 kHz and 200 kHz by means of Control Bits R1_DB(22:23), and should be chosen as a compromise between interference rejection, attenuation of the desired signal, and the AFC pull-in range. To compensate for manufacturing tolerances, the IF filter should be calibrated once after power-up. The IF filter calibration logic requires that the IF filter divider in Bits R6_DB(20:28) be set dependent on the crystal frequency. Once initiated by setting Bit R6_DB19, the calibration is performed automatically without any user intervention. The calibration time is 200 s, during which the ADF7020 should not be accessed. It is important not to initiate the calibration cycle before the crystal oscillator has fully settled. If the AGC loop is disabled, the gain of IF filter can be set to three levels using the filter_gain field, R9_DB(20:21). The filter gain is adjusted automatically, if the AGC loop is enabled. The signal in the image channel of the low IF mixer, located at a frequency of 400 kHz below the desired channel, is rejected due to the image rejection of the polyphase filter. The image rejection performance of the IF filter is subject to manufacturing tolerances, and, to some extent, temperature drift. To improve the image rejection, a calibration procedure can be performed as outlined in the Image Rejection Calibration section.
SW2
LNA
LO
Q (TO FILTER) MIXER LINEARITY [R6_DB18]
Figure 14. ADF7020 RF Front End
The LNA is followed by a quadrature downconversion mixer, which converts the RF signal to the IF frequency of 200 kHz. It is important to consider that the output frequency of the synthesizer must be programmed to a value 200 kHz below the center frequency of the received channel. The LNA has two basic operating modes: high gain/low noise mode and low gain/low power mode. To switch between these two modes, use the LNA_mode bit, R6_DB15. The mixer is also configurable between a low current and an enhanced linearity mode using the mixer_linearity bit, R6_DB18.
Table 5. LNA/Mixer Modes
Receiver Mode High Sensitivity Mode (default) RxMode2 Low Current Mode Enhanced Linearity Mode RxMode5 RxMode6 LNA Mode (R6_DB15) 0 1 1 1 1 0 LNA Gain Value R9_DB(21:20) 30 10 3 3 10 30
01975-PrG-014
Mixer Linearity (R6_DB18) 0 0 0 1 1 1
Sensitivity (DR = 9.6 kbps, fDEV = 10 kHz) -110.5 -104 -91 -101 TBD TBD
Rx Current Consumption (mA) 22 20 19 19 TBD TBD
Input IP3 (dBm) -35 -15.9 -3.2 6.8 -8.25 -28.8
Rev. PrH | Page 16 of 40
Preliminary Technical Data
RSSI/AGC SECTION
The RSSI is implemented as a successive compression log amp following the base-band channel filtering. The log amp achieves 3 dB log linearity. It also doubles as a limiter to convert the signal-to-digital levels for the FSK demodulator. The RSSI itself is used for amplitude shift keying (ASK) demodulation. In ASK mode, extra digital filtering is performed on the RSSI value. Offset correction is achieved using a switched capacitor integrator in feedback around the log amp. This uses the BB offset clock divide. The RSSI level is converted for user readback and digitally controlled AGC by an 80-level (7-bit) flash ADC. This level can be converted to input power in dBm.
OFFSET CORRECTION FSK DEMOD
ADF7020
RSSI Formula (Converting to dBm)
Input_Power [dBm] = -110 dBm + (Readback_Code + Gain_Mode_Correction ) x 0.5 where: Readback_Code is given by Bits RV7 to RV1 in the readback register (see Readback Format section). Gain_Mode_Correction is given by the values in Table 6. LNA gain and filter gain (LG2/LG1, FG2/FG1) are also obtained from the readback register.
Table 6. Gain Mode Correction Table
LNA Gain (LG2, LG1) H (10) M (01) M (01) M (01) L (00) Filter Gain (FG2, FG1) H (10) H (10) M (01) L (00) L (00) Gain Mode Correction 0 11 19 + 11 = 30 19 + 19 + 11 = 49 19 + 19 + 19 + 11 = 68
1
A
A
A
LATCH
IFWR
IFWR
IFWR
IFWR
CLK ADC
R
01975-PrG-015
RSSI ASK DEMOD
Figure 15. RSSI Block Diagram
RSSI Thresholds
When the RSSI is above AGC_HIGH_THRESHOLD, the gain is reduced. When the RSSI is below AGC_LOW_THRESHOLD, the gain is increased. A delay (AGC_DELAY) is programmed to allow for settling of the loop. The user programs the two threshold values (recommended defaults, 27 and 76) and the delay (default, 10). The default AGC setup values should be adequate for most applications. The threshold values must be chosen to be more than 30 apart for the AGC to operate correctly.
An additional factor should be introduced to account for losses in the front-end matching network/antenna.
FSK DEMODULATORS ON THE ADF7020
The two FSK demodulators on the ADF7020 are
* *
FSK correlator/demodulator Linear demodulator
Select these using the demod select bits, R4_DB(4:5).
FSK CORRELATOR/DEMODULATOR
The quadrature outputs of the IF filter are first limited and then fed to a pair of digital frequency correlators that perform bandpass filtering of the binary FSK frequencies at (IF + FDEV) and (IF - FDEV). Data is recovered by comparing the output levels from each of the two correlators. The performance of this frequency discriminator approximates that of a matched filter detector, which is known to provide optimum detection in the presence of AWGN.
FREQUENCY CORRELATOR I LIMITERS Q IF - FDEV IF + FDEV SLICER
Offset Correction Clock
In Register 3, the user should set the BB offset clock divide bits R3_DB(4:5) to give an offset clock between 1 MHz and 2 MHz, where: BBOS _CLK [Hz] = XTAL/(BBOS_CLK_DIVIDE) BBOS_CLK_DIVIDE can be set to 4, 8, or 16.
In Register 9, the user should select automatic gain control by selecting auto in R9_DB18 and auto in R9_DB19. The user should then program AGC low threshold R9_DB(4:10) and AGC high threshold R9_DB(11:17). The recommended/default values for the low and high thresholds are 30 and 70, respectively. In the AGC2 register the user should program the AGC delay to be long enough to allow the loop to settle. The recommended value is 10.
DATA SYNCHRONIZER
AGC Information
POST DEMOD FILTER
IF
Rx DATA
Rx CLK
01975-PrG-016
0 DB(4:13) DB(14) DB(8:15)
Figure 16. FSK Correlator/Demodulator Block Diagram
Rev. PrH | Page 17 of 40
ADF7020
Postdemodulator Filter
A second-order, digital low-pass filter removes excess noise from the demodulated bit stream at the output of the discriminator. The bandwidth of this postdemodulator filter is programmable and must be optimized for the user's data rate. If the bandwidth is set too narrow, performance is degraded due to intersymbol interference (ISI). If the bandwidth is set too wide, excess noise degrades the receiver's performance. Typically, the 3 dB bandwidth of this filter is set at approximately 0.75 times the user's data rate, using Bits R4_DB(6:15).
Preliminary Technical Data
To optimize the coefficients of the FSK correlator, two additional bits, R6_DB14 and R6_DB29, must be assigned. The value of these bits depends on whether K (as defined above) is odd or even. These bits are assigned according to Table 7 and Table 8.
Table 7. When K Is Even
K Even Even K/2 Even Odd R6_DB14 0 0 R6_DB29 0 1
Table 8. When K Is Odd
K Odd Odd (K + 1)/2 Even Odd R6_DB14 1 1 R6_DB29 0 1
Bit Slicer
The received data is recovered by threshold detecting the output of the postdemodulator low-pass filter. In the correlator/ demodulator, the binary output signal levels of the frequency discriminator are always centered on zero. Therefore, the slicer threshold level can be fixed at zero and the demodulator performance is independent of the run-length constraints of the transmit data bit stream. This results in robust data recovery, which does not suffer from the classic baseline wander problems that exist in the more traditional FSK demodulators. Frequency errors are removed by an internal AFC loop that measures the average IF frequency at the limiter output and applies a frequency correction value to the fractional-N synthesizer. This loop should be activated when the frequency errors are greater than approximately 40% of the transmit frequency deviation (see the AFC Section).
Postdemodulator Bandwidth Register Settings
The 3 dB bandwidth of the postdemodulator filter is controlled by Bits R4_ DB(6:15) and is given by
Post _ Demod _ BWSetting = 210 x 2 x FCUTOFF DEMOD _ CLK
where FCUTOFF is the target 3 dB bandwidth in Hz of the postdemodulator filter. This should typically be set to 0.75 times the data rate (DR). Some sample settings for the FSK correlator/demodulator are DEMOD_CLK = 5 MHz DR = 9.6 kbps FDEV = 20 kHz Therefore, FCUTOFF = 0.75 x 9.6 x 103 Hz Post_Demod_BW = 211 7.2 x 103 Hz/(5 MHz) Post_Demod_BW = Round(9.26) = 9 and K = Round(200 kHz)/20 kHz) = 10 Discriminator_BW = (5 MHz x 10)/(800 x 103) = 62.5 = 63 (rounded to nearest integer)
Table 9.
Data Synchronizer
An oversampled digital PLL is used to resynchronize the received bit stream to a local clock. The oversampled clock rate of the PLL (CDR_CLK) must be set at 32 times the data rate. See the notes for the Register 3--Receiver Clock Register section for a definition of how to program. The clock recovery PLL can accommodate frequency errors of up to 2%.
FSK Correlator Register Settings
To enable the FSK correlator/demodulator, Bits R4_DB(5:4) should be set to [01]. To achieve best performance, the bandwidth of the FSK correlator must be optimized for the specific deviation frequency that is used by the FSK transmitter. The discriminator BW is controlled in Register 6 by R6_DB(4:13) and is defined as
Discriminator _ BW = (DEMOD _ CLK x K ) /(800 x 10 )
3
where: DEMOD_CLK is as defined in the Register 3--Receiver Clock Register section, Note 2. K = Round(200e3/FSK Deviation)
Setting Name Post_Demod_BW Discriminator BW Dot Product Rx Data Invert
Register Address R4_DB(6:15) R6_DB(4:13) R6_DB14 R6_DB29
Value 0x09 0x3F 0 0
Rev. PrH | Page 18 of 40
Preliminary Technical Data
LINEAR FSK DEMODULATOR
A block diagram of the linear FSK demodulator is shown in Figure 17.
MUX 1 ADC RSSI OUTPUT LEVEL IF 7 SLICER
ADF7020
The 3 dB bandwidth of this filter is typically set at approximately 0.75 times the user data rate and is assigned by R4 _DB(6:15) as Post_Demod_BW_Setting = 210 x 2 x FCUTOFF DEMOD_CLK
ENVELOPE DETECTOR
LIMITER Q FREQUENCY LINEAR DISCRIMINATOR
AVERAGING FILTER
I
Rx DATA
where FCUTOFF is the target 3 dB bandwidth in Hz of the postdemodulator filter.
AFC SECTION
01975-PrG-017
FREQUENCY READBACK AND AFC LOOP
DB(6:15)
Figure 17. Block Diagram of Frequency Measurement System and ASK.OOK/Linear FSK Demodulator
This method of frequency demodulation is useful when very short preamble length is required and the system protocol cannot support the overhead of the settling time of the internal feedback AFC loop settling. A digital frequency discriminator provides an output signal that is linearly proportional to the frequency of the limiter outputs. The discriminator output is then filtered and averaged using a combined averaging filter and envelope detector. The demodulated FSK data is recovered by threshold-detecting the output of the averaging filter, as shown in Figure 17. In this mode, the slicer output shown in Figure 17 is routed to the data synchronizer PLL for clock synchronization. To enable the linear FSK demodulator, set Bits R4_DB(4:5) to [00]. The 3 dB bandwidth of the postdemodulation filter is set in the same way as the FSK correlator/demodulator, which is set in R4_DB(6:15) and is defined as
The ADF7020 supports a real-time AFC loop, which is used to remove frequency errors that can arise due to mismatches between the transmit and receive crystals. This uses the frequency discriminator block, as described in the Linear FSK Demodulator section (see Figure 17). The discriminator output is filtered and averaged to remove the FSK frequency modulation using a combined averaging filter and envelope detector. In FSK mode, the output of the envelope detector provides an estimate of the average IF frequency. Two methods of AFC, external and internal, are supported on the ADF7020 (in FSK mode only).
External AFC
The user reads back the frequency information through the ADF7020 serial port and applies a frequency correction value to the fractional-N synthesizer's N divider. The frequency information is obtained by reading the 16-bit signed AFC_readback, as described in the Readback Format section, and applying the following formula: FREQ_RB [Hz] = (AFC_READBACK x DEMOD_CLK)/215 Note that while the AFC_READBACK value is a signed number, under normal operating conditions it is positive. In the absence of frequency errors, the FREQ_RB value is equal to the IF frequency of 200 kHz.
Post _ Demod _ BW _ Setting = where:
210 x 2 x FCUTOFF DEMOD _ CLK
Internal AFC
The ADF7020 supports a real-time internal automatic frequency control loop. In this mode, an internal control loop automatically monitors the frequency error and adjusts the synthesizer N divider using an internal PI control loop. The internal AFC control loop parameters are controlled in Register 11. The internal AFC loop is activated by setting R11_DB20 to 1. A scaling coefficient must also be entered, based on the crystal frequency in use. This is set up in R11_DB(4:19) and should be calculated using AFC_Scaling_Coefficient = (500 x 224)/XTAL Therefore, using a 10 MHz XTAL yields an AFC scaling coefficient of 839.
FCUTOFF is the target 3 dB bandwidth in Hz of the postdemodulator filter. DEMOD_CLK is as defined in the Register 3--Receiver Clock Register section, Note 2.
ASK/OOK Operation
ASK/OOK demodulation is activated by setting Bits R4_DB(4:5) to [10]. Digital filtering and envelope detecting the digitized RSSI input via MUX 1, as shown in Figure 17, perform ASK/OOK demodulation. The bandwidth of the digital filter must be optimized to remove any excess noise without causing ISI in the received ASK/OOK signal.
Rev. PrH | Page 19 of 40
ADF7020
Maximum AFC Range
The maximum AFC frequency range is 100 kHz. This is set by the maximum IF filter bandwidth of 200 kHz. Using the minimum IF filter bandwidth of 100 kHz, the AFC range is 50 kHz. When AFC errors have been removed using either the internal or external AFC, further improvement in the receiver's sensitivity can be obtained by reducing the IF filter bandwidth using Bits R1_DB(22:23).
Preliminary Technical Data
This feature can be used to alert the microprocessor that a valid channel has been detected. It relaxes the computational requirements of the microprocessor and reduces the overall power consumption. The INT/LOCK is automatically deasserted again after nine data clock cycles. The automatic sync/ID word detection feature is enabled by selecting demod mode 2 or 3 in the demodulator setup register. Do this by setting R4_DB(25:23) = [010] or [011]. Bits R5_DB(4:5) are used to set the length of the sync/ID word, which can be either 12, 16, 20, or 24 bits long. The transmitter must transmit the MSB of the sync byte first and the LSB last to ensure proper alignment in the receiver sync byte detection hardware. For systems using FEC, an error tolerance parameter can also be programmed that accepts a valid match when up to three bits of the word are incorrect. The error tolerance value is assigned in R5_DB(6:7).
AUTOMATIC SYNC WORD RECOGNITION
The ADF7020 also supports automatic detection of the sync or ID fields. To activate this mode, the sync (or ID) word must be preprogrammed into the ADF7020. In receive mode, this preprogrammed word is compared to the received bit stream and, when a valid match is identified, the external pin INT/LOCK is asserted by the ADF7020.
Rev. PrH | Page 20 of 40
Preliminary Technical Data APPLICATIONS SECTION
LNA/PA MATCHING
The ADF7020 exhibits optimum performance in terms of sensitivity, transmit power, and current consumption only if its RF input and output ports are properly matched to the antenna impedance. For cost-sensitive applications, the ADF7020 is equipped with an internal Rx/Tx switch, which facilitates the use of a simple combined passive PA/LNA matching network. Alternatively, an external Rx/Tx switch such as the Analog Devices ADG919 can be used, which yields a slightly improved receiver sensitivity and lower transmitter power consumption.
ADF7020
networks in a back-to-back configuration. Due to the asymmetry of the network with respect to ground, a compromise between the input reflection coefficient and the maximum differential signal swing at the LNA input must be established. The use of appropriate CAD software is strongly recommended for this optimization. Depending on the antenna configuration, the user might need a harmonic filter at the PA output to satisfy the spurious emission requirement of the applicable government regulations. The harmonic filter can be implemented in various ways, such as a discrete LC-filter. Dielectric low-pass filter components such as the LFL18924MTC1A052 (for operation in the 915 MHz band), or LFL18869MTC2A160 (for operation in the 868 MHz band), both by Murata Mfg. Co., Ltd., represent an attractive alternative to discrete designs. The immunity of the ADF7020 to strong out-of-band interference can be improved by adding a bandpass filter in the Rx path. Apart from discrete designs, SAW or dielectric filter components such as the SAFCH869MAM0T00B0S, SAFCH915MAL0N00B0S, DCFB2869MLEJAA-TT1, or DCFB3915MLDJAA-TT1, all by Murata Mfg. Co., Ltd., are well suited for this purpose.
External Rx/Tx Switch
Figure 18 shows a configuration using an external Rx/Tx switch. This configuration allows an independent optimization of the matching and filter network in the transmit and receive path, and is, therefore, more flexible and less difficult to design than the configuration using the internal Rx/Tx switch. The PA is biased through inductor L1, while C1 blocks dc current. Both elements, L1 and C1, also form the matching network, which transforms the source impedance into the optimum PA load impedance, ZOPT_PA.
VBAT L1 OPTIONAL LPF ANTENNA ZOPT_PA ZIN_RFIN OPTIONAL BPF (SAW) CA LA RFIN LNA RFINB PA_OUT PA
Internal Rx/Tx Switch
Figure 19 shows the ADF7020 in a configuration where the internal Rx/Tx switch is used with a combined LNA/PA matching network. Depending on the application, the slight performance degradation caused by the internal Rx/Tx switch might be acceptable, allowing the user to take advantage of the cost-saving potential of this solution. The design of the combined matching network must compensate for the reactance presented by the networks in the Tx and the Rx paths, taking the state of the Rx/Tx switch into consideration.
VBAT L1 PA_OUT PA ANTENNA OPTIONAL BPF OR LPF CA LA ZOPT_PA ZIN_RFIN RFIN LNA RFINB
ZIN_RFIN CB
Rx/Tx - SELECT
ADF7020
Figure 18. ADF7020 with External Rx/Tx Switch
01975-PrG-018
ADG919
ZIN_RFIN CB
Due to the differential LNA input, the LNA matching network must be designed to provide both a single-ended to differential conversion and a complex conjugate impedance match. The network with the lowest component count that can satisfy these requirements is the configuration shown in Figure 18, which consists of two capacitors and one inductor. A first-order implementation of the matching network can be obtained by understanding the arrangement as two L-type matching
ADF7020
Figure 19. ADF7020 with Internal Rx/Tx Switch
The procedure typically requires several iterations until an acceptable compromise has been reached. The successful implementation of a combined LNA/PA matching network for the ADF7020 is critically dependent on the availability of an
Rev. PrH | Page 21 of 40
01975-PrG-019
ZOPT_PA depends on various factors such as the required output power, the frequency range, the supply voltage range, and the temperature range. Selecting an appropriate ZOPT_PA helps to minimize the Tx current consumption in the application. This datasheet contains a number of ZOPT_PA values for representative conditions. Under certain conditions, however, it is recommended to obtain a suitable ZOPT_PA value by means of a load-pull measurement.
C1
ADF7020
accurate electrical model for the PC board. In this context, the use of a suitable CAD package is strongly recommended. To avoid this effort, the reference design provided for the ADF7020 RF module can be used. As with the external Rx/Tx switch, an additional LPF or BPF might be required to suppress harmonics in the transmit spectrum or to improve the resilience of the receiver against out-of-band interferers.
Preliminary Technical Data
IMAGE REJECTION CALIBRATION
The image channel in this receiver, with an IF at 200 kHz, is at -200 kHz or +400 kHz below the desired signal. The polyphase filter rejects this image with an asymmetric frequency response. The image rejection performance of the receiver is dependent on how well matched in amplitude the I and Q signals are, and how perfect the quadrature is between them, that is, how close to 90 apart they are. The uncalibrated image rejection performance is approximately 30 dB. However, it is possible to improve on this performance by adjusting the I/Q phase/gain adjust bits in Register 10, resulting in an image rejection of approximately 45 dB. Bits R10_DB(24:27) adjust the relative phase of the signal and Bits R10_DB(16:20) adjust the relative amplitude (see Figure 20).
LNA MIXERS POLYPHASE FILTER
TRANSMIT PROTOCOL AND CODING CONSIDERATIONS
SYNC WORD ID FIELD
01975-PrG-042
PREAMBLE
DATA FIELD
CRC
Figure 20. Typical Format of a Transmit Protocol
A dc-free preamble pattern is recommended for FSK/ASK/ OOK demodulation. The recommended preamble pattern is a dc-free pattern such as a 10101010... pattern. Preamble patterns with longer run-length constraints such as 11001100.... can also be used. However, this results in a longer synchronization time of the received bit stream in the receiver. Manchester coding can be used for the entire transmit protocol. However, the remaining fields that follow the preamble header do not have to use dc-free coding. For these fields, the ADF7020 can accommodate coding schemes with a run-length of up to 6 bits without any performance degradation. If longer run-length coding must be supported, the ADF7020 has several other features that can be activated. These involve a range of programmable options that allow the envelope detector output to be frozen after preamble acquisition.
GAIN LO I LO Q
PHASE
Figure 20. Phase/Gain Adjustment on ADF7020
DEVICE PROGRAMMING AFTER INITIAL POWER-UP
Basic mode is the minimum number of write sequences to power up the device. Enhanced mode uses the additional features of the ADF7020 to tailor the part to a particular application such as setting up a sync byte sequence or doing automatic frequency control. The sample setting is for the following setup:
FRF = 915 MHz, FSK, DR = 9.868 kbps, ICP = 1.44 mA FDEV = 50 kHz, XTAL = 10 MHz, Correlator/Demodulator
Rev. PrH | Page 22 of 40
01975-PrG-020
Preliminary Technical Data
REGISTER WRITE WRITE TO R0 PRIMARY FUNCTION PROGRAM FREQUENCY EXAMPLE SETTING 0x72DC 0000
REGISTER WRITE WRITE TO R0 PRIMARY FUNCTION PROGRAM FREQUENCY
ADF7020
EXAMPLE SETTING 0x0000
WRITE TO R1
SET UP OSCILLATOR AND IF FILTER
0x86 9011
WRITE TO R1
SET UP OSCILLATOR AND IF FILTER
0x0000
01975-PrG-021
WRITE TO R2
SET UP MODULATION PARAMETERS
0x8022 6012
WRITE TO R3
SET UP Rx CLOCKS
0x0000
Figure 21. Basic Mode--Tx
WRITE TO R4
SET UP DEMOD
0x0000
REGISTER WRITE WRITE TO R0
PRIMARY FUNCTION PROGRAM FREQUENCY
EXAMPLE SETTING
WRITE TO R5
0x7ADB D710
SET UP SYNC BYTE SEQUENCE
0x0000
WRITE TO R1
SET UP OSCILLATOR AND IF FILTER
WRITE TO R6
SET UP Rx MODE
0x0000
0x86 9011
WRITE TO R9
WRITE TO R3
SET UP Rx CLOCKS
0x64 2053
SET UP AGC PARAMETERS AND LNA/GAIN FILTER
0x0000
WRITE TO R10
WRITE TO R4
SET UP DEMOD
0x0194
SET UP I/Q GAIN/PHASE ADJUST
0x0000
01975-PrG-022
WRITE TO R11
WRITE TO R6
SET UP Rx MODE
SET UP AFC PARAMETERS
0x0000
0x2C82 0326
Figure 23. Enhanced Mode--Rx
Figure 22. Basic Mode--Rx
REGISTER WRITE WRITE TO R0 PRIMARY FUNCTION CHANGE FREQUENCY AND CHANGE MODE TO Rx EXAMPLE SETTING 0x0000
01975-PrG-024
Figure 24. Change Mode from Tx to Rx
Rev. PrH | Page 23 of 40
01975-PrG-023
ADF7020 SERIAL INTERFACE
The serial interface allows the user to program the eleven 32-bit registers using a 3-wire interface (SCLK, SDATA, and SLE). It consists of a level shifter, 32-bit shift register and eleven latches. Signals should be CMOS compatible. The serial interface is powered by the regulator, and, therefore, is inactive when CE is low. Data is clocked into the register, MSB first, on the rising edge of each clock (SCLK). Data is transferred to one of eleven latches on the rising edge of SLE. The destination latch is determined by the value of the four control bits (C4 to C1). These are the bottom four LSBs, DB3 to DB0, as shown in the timing diagram in Figure 2. Data can also be read back on the SREAD pin.
RSSI Readback
Preliminary Technical Data
The RSSI readback operation yields valid results in Rx mode with ASK or FSK signals. The format of the readback word is shown in Figure 25. It is comprised of the RSSI level information (Bits RV1 to RV7), the current filter gain (FG1, FG2), and the current LNA gain (LG1, LG2) setting. The filter and LNA gain are coded in accordance with the definitions in Register 9. With the reception of ASK modulated signals, averaging of the measured RSSI values improves accuracy. The input power can be calculated from the RSSI readback value as outlined in the RSSI/AGC Section.
Battery Voltage ADCIN/Temperature Sensor Readback
The battery voltage is measured at Pin VDD4. The readback information is contained in Bits RV1 to RV7. This also applies for the readback of the voltage at the ADCIN pin and the temperature sensor. From the readback information, the battery or ADCIN voltage can be determined using VBATTERY = (Battery_Voltage_Readback)/21.1 VADCIN = (ADCIN_Voltage_Readback)/42.1
READBACK FORMAT
The readback operation is initiated by writing a valid control word to the readback register and setting the readback-enable bit (R7_DB8 = 1). The readback can begin after the control word has been latched with the SLE signal. SLE must be kept high while the data is being read out. Each active edge at the SCLK pin clocks the readback word out successively at the SREAD pin, as shown in Figure 25, starting with the MSB first. The data appearing at the first clock cycle following the latch operation must be ignored.
Silicon Revision Readback
The silicon revision readback word is valid without setting any other registers, especially directly after power-up. The silicon revision word is coded with four quartets in BCD format. The product code (PC) is coded with two quartets extending from Bits RV9 to RV16. The revision code (RV) is coded with two quartets extending from Bits RV1 to RV8. The product code should read back as PC = #20h. The current revision code should read as RC = #30h.
AFC Readback
The AFC readback is valid only during the reception of FSK signals with either the linear or correlator demodulator active. The AFC readback value is formatted as a signed 16-bit integer comprised of Bits RV1 to RV16, and is scaled according to the following formula: FREQ_RB [Hz] = (AFC_READBACK x DEMOD_CLK)/215 In the absence of frequency errors, the FREQ_RB value is equal to the IF frequency of 200 kHz. Note that, for the AFC readback to yield a valid result, the down-converted input signal must not fall outside the bandwidth of the analogue IF filter. At low-input signal levels, the variation in the readback value can be improved by averaging.
Filter Calibration Readback
The filter calibration readback word is contained in Bits RV1 to RV8, and is for diagnostic purposes only. Using the automatic filter calibration function, accessible through Register 6, is recommended.
READBACK MODE DB15 AFC READBACK RSSI READBACK BATTERY VOLTAGE/ADCIN/ TEMP. SENSOR READBACK SILICON REVISION FILTER CAL READBACK RV16 X DB14 RV15 X DB13 RV14 X DB12 RV13 X DB11 RV12 X DB10 RV11 LG2
READBACK VALUE DB9 RV10 LG1 DB8 RV9 FG2 DB7 RV8 FG1 DB6 RV7 RV7 DB5 RV6 RV6 DB4 RV5 RV5 DB3 RV4 RV4 DB2 RV3 RV3 DB1 RV2 RV2 DB0 RV1 RV1
X RV16 0
X RV15 0
X RV14 0
X RV13 0
X RV12 0
X RV11 0
X RV10 0
X RV9 0
X RV8 RV8
RV7 RV7 RV7
RV6 RV6 RV6
RV5 RV5 RV5
RV4 RV4 RV4
RV3 RV3 RV3
RV2 RV2 RV2
RV1 RV1 RV1
01975-PrG-025
Figure 25. Readback Value Table
Rev. PrH | Page 24 of 40
Preliminary Technical Data
REGISTER 0--N REGISTER
PLL ENABLE Tx/Rx
ADF7020
MUXOUT
8-BIT INTEGER-N
15-BIT FRACTIONAL-N
ADDRESS BITS
DB31
DB30
DB29
PLE1 DB28
DB27
DB26
DB25
DB24
DB23
DB22
DB21
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
C4 (0) DB3
C3 (0) DB2
C2 (0) DB1
TR1 0 1
TRANSMIT/ RECEIVE TRANSMIT RECEIVE
M15 0 0 0 . . . 1 1 1 1
M14 0 0 0 . . . 1 1 1 1
M13 0 0 0 . . . 1 1 1 1
... ... ... ... ... ... ... ... ... ... ...
M3 1 1 1 . . . 1 1 1 1
M2 0 0 1 . . . 0 0 1 1
M1 0 1 0 . . . 0 1 0 1
FRACTIONAL DIVIDE RATIO 4 5 6 . . . 32764 32765 32766 32767
PLE1 PLL ENABLE 0 1 M3 0 0 0 0 1 1 1 1 M2 0 0 1 1 0 0 1 1 M1 0 1 0 1 0 1 0 1 PLL OFF PLL ON MUXOUT REGULATOR READY (DEFAULT) R DIVIDER OUTPUT N DIVIDER OUTPUT DIGITAL LOCK DETECT ANALOG LOCK DETECT THREE-STATE PLL TEST MODES - TEST MODES
N8 0 0 . . . 1 1 1
N7 0 0 . . . 1 1 1
N6 0 1 . . . 1 1 1
N5 1 0 . . . 1 1 1
N4 1 0 . . . 1 1 1
N3 1 0 . . . 1 1 1
N2 1 0 . . . 0 1 1
N1 1 0 . . . 1 0 1
N COUNTER DIVIDE RATIO 31 32 . . . 253 254 255
01975-PrG-026
Figure 26.
Notes: 1. 2. The Tx/Rx bit (R0_DB27) configures the part in Tx or Rx mode and also controls the state of the internal Tx/Rx switch.
FOUT = Fractional-N XTAL x (Integer-N + ). R 215
Rev. PrH | Page 25 of 40
C1 (0) DB0
M15
M14
M13
M12
M11
M10
TR1
M3
M2
M1
M9
M8
M7
M6
M5
M4
M3
M2
M1
N8
N7
N6
N5
N4
N3
N2
N1
ADF7020
REGISTER 1--OSCILLATOR/FILTER REGISTER
IF FILTER BW VCO BAND CP CURRENT
Preliminary Technical Data
VCO BIAS
CLOCKOUT DIVIDE
XTAL DOUBLER
VCO ADJUST
XOSC ENABLE
R COUNTER
ADDRESS BITS
DB31
DB30
DB29
DB28
DB27
DB26
DB25
DB24
DB23
DB22
DB21
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
C4 (0) DB3
C3 (0) DB2
C2 (0) DB1
VA2 0 0 1 1
VA1 0 1 0 1
FREQUENCY OF OPERATION 880-950 870-940 860-930 850-920
X1 XTAL OSC 0 OFF 1 ON
V1 VCO BIAS CURRENT 0.5mA 1mA 8mA 0 1
VCO Band MHz 866-940 433-470
R3 0 0 . . . 1
R2 0 1 . . . 1
R1 1 0 . . . 1
RF R COUNTER DIVIDE RATIO 1 2 . . . 7
VB4 0 0 . 1
VB3 0 0 . 1
VB2 0 1 . 1
VB1 1 0 . 1
D1 0 1
XTAL DOUBLER DISABLE ENABLED
IR2 IR1 0 0 1 1 0 1 0 1
FILTER BANDWIDTH 100kHz 150kHz 200kHz NOT USED
CP2 0 0 1 1
ICP(MA) CP1 RSET 3.6k 0 1 0 1 0.3 0.9 1.5 2.1
Figure 27.
Notes: 1. 2. Set the VCO adjust bits (R1_DB(20:21) to 0 for normal operation.
FOUT = Fractional-N XTAL x (Integer-N + ). R 215
Rev. PrH | Page 26 of 40
01975-PrG-027
CL4 0 0 0 . . . 1
CL3 0 0 0 . . . 1
CL2 0 0 1 . . . 1
CL1 0 1 0 . . . 1
CLKOUT DIVIDE RATIO OFF 2 4 . . . 30
C1 (1) DB0
VA2
VA1
DD2
DD1
VB4
VB3
VB2
VB1
CL4
CL3
CL2
CL1
IR2
IR1
D1
R3
R2
R1
V1
X1
Preliminary Technical Data
REGISTER 2--TRANSMIT MODULATION REGISTER (ASK/OOK MODE)
PA BIAS GFSK MOD CONTROL MODULATION PARAMETER POWER AMPLIFIER MODULATION SCHEME
MUTE PA UNTIL LOCK PA ENABLE INDEX COUNTER TxDATA INVERT
ADF7020
ADDRESS BITS
DB31
DB30
DB29
DB28
DB27
DB26
DB25
DB24
DB23
DB22
DB21
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
C4 (0) DB3
C3 (0) DB2
C2 (1) DB1
PE1 IC2 IC1 MC3 MC2 MC1 X X X X X 0 1
POWER AMPLIFIER OFF ON
DI1 0 1 TxDATA TxDATA
MUTE PA UNTIL MP1 LOCK DETECT HIGH 0 1 OFF ON
PA2 0 1 0 1
PA1 0 0 1 1
PA BIAS 5A 7A 9A 11A
S3 0 0 1 0 1
S2 0 0 0 1 1
S1 0 1 0 1 1
MODULATION SCHEME FSK GFSK ASK OOK G - OOK
POWER AMPLIFIER OUTPUT LOW LEVEL D6 . D5 D2 D1 X 0 0 0 0 . . 1 X X 0 0 . . . 1 . . . . . . . 1 X X 0 0 1 . . 1 X X 0 1 0 . . 1 OOK MODE PA OFF -16.0dBm -16 + 0.45dBm -16 + 0.90dBm . . 13dBm
POWER AMPLIFIER OUTPUT HIGH LEVEL P6 . . P2 P1 0 0 0 0 . . 1 . . . . . . 1 . . . . . . 1 X 0 0 1 . . 1 X 0 1 0 . . 1 PA OFF -16.0dBm -16 + 0.45dBm -16 + 0.90dBm . . 13dBm
C1 (0) DB0
01975-PrG-028
MC3
MC2
MC1
MP1
PA2
PA1
Figure 28.
Note: 1. See the Transmitter section for a description of how the PA bias affects power amplifier level. Default level is 9 A.
Rev. PrH | Page 27 of 40
PE1
DI1
IC2
IC1
D9
D8
D7
D6
D5
D4
D3
D2
D1
P6
P5
P4
P3
P2
P1
S3
S2
S1
ADF7020
REGISTER 2--TRANSMIT MODULATION REGISTER (FSK MODE)
INDEX COUNTER
Preliminary Technical Data
MUTE PA UNTIL LOCK PA ENABLE
TxDATA INVERT
PA BIAS
GFSK MOD CONTROL
MODULATION PARAMETER
POWER AMPLIFIER
MODULATION SCHEME
ADDRESS BITS
DB31
DB30
DB29
DB28
DB27
DB26
DB25
DB24
DB23
DB22
DB21
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
C4 (0) DB3
C3 (0) DB2
C2 (1) DB1
PE1 IC2 IC1 MC3 MC2 MC1 X X X X X 0 1
POWER AMPLIFIER OFF ON
DI1 0 1 TxDATA TxDATA
FOR FSK MODE, D2 .... D3 D9 0 0 0 0 . 1 .... .... .... .... .... .... 0 0 0 0 . 1 0 0 1 1 . 1
MUTE PA UNTIL MP1 LOCK DETECT HIGH D1 0 1 0 1 . 1 F DEVIATION PLL MODE 1 x FSTEP 2 x FSTEP 3 x FSTEP . 511 x FSTEP 0 1 OFF ON
PA2 0 0 1 1
PA1 0 1 0 1
PA BIAS 5A 7A 9A 11A
S3 0 0 0 0 1
S2 0 0 1 1 1
S1 0 1 0 1 1
MODULATION SCHEME FSK GFSK ASK OOK G - OOK
POWER AMPLIFIER OUTPUT LEVEL P1 P2 . . P6 0 0 0 0 . . 1 . . . . . . 1 . . . . . . 1 X 0 0 1 . . 1 X 0 1 0 . . 1 PA OFF -16.0dBm -16 + 0.45dBm -16 + 0.90dBm . . 13dBm
C1 (0) DB0
01975-PrG-029
MC2
MC3
MC1
MP1
PA2
PA1
Figure 29.
Notes:
1. 2.
FSTEP = PFD / 214
.
PA Bias default = 9 A.
Rev. PrH | Page 28 of 40
PE1
DI1
IC2
IC1
D9
D8
D7
D6
D5
D4
D3
D2
D1
P6
P5
P4
P3
P2
P1
S3
S2
S1
Preliminary Technical Data
REGISTER 2--TRANSMIT MODULATION REGISTER (GFSK/GOOK MODE)
MUTE PA UNTIL LOCK PA ENABLE INDEX COUNTER TxDATA INVERT
PA BIAS GFSK MOD CONTROL MODULATION PARAMETER POWER AMPLIFIER MODULATION SCHEME
ADF7020
ADDRESS BITS
DB31
DB30
DB29
DB28
DB27
DB26
DB25
DB24
DB23
DB22
DB21
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
C4 (0) DB3
C3 (0) DB2
C2 (1) DB1
D7 0 0 0 0 . 1 TxDATA TxDATA
... ... ... ... ... ... ...
D3 0 0 0 0 . 1
D2 0 0 1 1 . 1
D1 0 1 0 1 . 1
DIVIDER_FACTOR INVALID 1 2 3 . 127
PE1 0 1
POWER AMPLIFIER OFF ON
DI1 0 1
MUTE PA UNTIL MP1 LOCK DETECT HIGH 0 1 OFF ON
PA2 0 1 0 1
PA1 0 0 1 1
PA BIAS 5A 7A 9A 11A D9 0 0 1 1 INDEX_COUNTER 16 32 64 128 D8 0 1 0 1
GAUSSIAN - OOK MODE BLEED/BUFFER OFF OUTPUT BUFFER ON BLEED CURRENT ON BLEED/BUFFER ON
S3 0 0 1 0 1
S2 0 0 0 1 1
S1 0 1 0 1 1
MODULATION SCHEME FSK GFSK ASK OOK G - OOK
IC2 0 0 1 1
IC1 0 1 0 1
POWER AMPLIFIER OUTPUT LEVEL P1 P2 . . P6 0 0 0 0 . . 1 . . . . . . 1 . . . . . . 1 X 0 0 1 . . 1 X 0 1 0 . . 1 PA OFF -16.0dBm -16 + 0.45dBm -16 + 0.90dBm . . 13dBm
MC3 MC2 MC1 GFSK_MOD_CONTROL 0 0 . 1 0 0 . 1 0 1 . 1 0 1 . 7
C1 (0) DB0
01975-PrG-030
MC2
MC3
MC1
MP1
PA2
PA1
Figure 30.
Notes: 1. 2. 3. GFSK_DEVIATION = (2GFSK_MOD_CONTROL x PFD)/212. DR = PFD/(INDEX_COUNTER x DIVIDER_FACTOR). PA Bias default = 9 A.
Rev. PrH | Page 29 of 40
PE1
DI1
IC2
IC1
D9
D8
D7
D6
D5
D4
D3
D2
D1
P6
P5
P4
P3
P2
P1
S3
S2
S1
ADF7020
REGISTER 3--RECEIVER CLOCK REGISTER
Preliminary Technical Data
DEMOD CLOCK DIVIDE BB OFFSET CLOCK DIVIDE
SEQUENCER CLOCK DIVIDE
CDR CLOCK DIVIDE
ADDRESS BITS
DB31
DB30
DB29
DB28
DB27
DB26
DB25
DB24
DB23
DB22
DB21
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1 C2(1)
C4(0)
C3(0)
SK8 0 0 . 1 1
SK7 0 0 . 1 1
... ... ... ... ... ...
SK3 0 0 . 1 1
SK2 0 1 . 1 1
SK1 1 0 . 0 1
SEQ_CLK_DIVIDE 1 2 . 254 255 OK2 0 0 1 1
BK2 0 0 1 OK1 0 1 0 1
BK1 0 1 x
BBOS_CLK_DIVIDE 4 8 16
DEMOD_CLK_DIVIDE 4 1 2 3
FS8 0 0 . 1 1
FS7 0 0 . 1 1
... ... ... ... ... ...
FS3 0 0 . 1 1
FS2 0 1 . 1 1
FS1 1 0 . 0 1
CDR_CLK_DIVIDE
01975-PrG-031
1 2 . 254 255
Figure 31.
Notes: 1. Baseband offset clock frequency (BBOS_CLK) must be greater than 1 MHz and less than 2 MHz, where:
BBOS _ CLK = XTAL BBOS _ CLK _ DIVIDE
2.
The demodulator clock (DEMOD_CLK) must be < 12 MHz for FSK and < 6 MHz for ASK, where:
DEMOD _ CLK = XTAL DEMOD _ CLK _ DIVIDE
3.
Data/clock recovery frequency (CDR_CLK) should be within 2% of (32 x data rate), where:
CDR _ CLK = DEMOD _ CLK CDR _ CLK _ DIVIDE
Note that this might affect your choice of XTAL, depending on the desired data rate. 4. The sequencer clock (SEQ_CLK) supplies the clock to the digital receive block. It should be close to 100 kHz for FSK and close to 40 kHz for ASK:
SEQ _ CLK = XTAL SEQ _ CLK _ DIVIDE
Rev. PrH | Page 30 of 40
C1(1)
OK2
OK1
BK2
BK1
SK8
SK7
SK6
SK5
SK4
SK3
SK2
SK1
FS8
FS7
FS6
FS5
FS4
FS3
FS2
FS1
IR2
IR1
DB0
Preliminary Technical Data
REGISTER 4--DEMODULATOR SETUP REGISTER
DEMOD LOCK/ DB24 SYNC WORD MATCH DEMOD SELECT
ADF7020
DEMODULATOR LOCK SETTING
POSTDEMODULATOR BW
ADDRESS BITS
DB31
DB30
DB29
DB28
DB27
DB26
DB25
DB23
DB22
DB21
DB20
DB19
DB18
DB17
DB16
DW10 DB15
DW9 DB14
DW8 DB13
DW7 DB12
DB11
DW5 DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1 C2(0)
C4(0)
C3(1)
DS2 0 0 1 1 DEMOD MODE LM2 LM1 DL8 0 1 2 3 4 5 0 0 0 0 1 1 0 0 1 1 0 1 0 1 0 1 X DL8 DEMOD LOCK/SYNC WORD MATCH SERIAL PORT CONTROL - FREE RUNNING SERIAL PORT CONTROL - LOCK THRESHOLD SYNC WORD DETECT - FREE RUNNING SYNC WORD DETECT - LOCK THRESHOLD INTERRUPT/LOCK PIN LOCKS THRESHOLD DEMOD LOCKED AFTER DL8-DL1 BITS INT/LOCK PIN - - OUTPUT OUTPUT INPUT -
DS1 0 1 0 1
DEMODULATOR TYPE LINEAR DEMODULATOR CORRELATOR/DEMODULATOR ASK/OOK INVALID
MODE5 ONLY DL8 0 0 0 . 1 1 DL7 0 0 0 . 1 1 ... ... ... ... ... ... ... DL3 0 0 0 . 1 1 DL2 0 0 1 . 1 1 DL1 0 1 0 . 0 1 LOCK_THRESHOLD_TIMEOUT 0 1 2 . 254 255
C1(0)
01975-PrG-032
DW2
DW6
DW4
DW3
DW1
LM2
LM1
DS2
Figure 32.
Notes : 1. 2. 3. 4. The cutoff frequency of the postdemodulator filter should typically be 0.75 times the data rate. Demodulator modes 1, 3, 4, and 5 are modes that can be activated to allow the ADF7020 to demodulate data-encoding schemes that have run-length constraints greater than 7. Post_Demod_BW = 211 FCUTOFF/DEMOD_CLK. For Mode 5, the timeout delay to lock threshold = (LOCK_THRESHOLD_SETTING)/SEQ_CLK, where SEQ_CLK is defined in the Register 3--Receiver Clock Register section.
Rev. PrH | Page 31 of 40
DS1
DL6
DL5
DL4
DL3
DL2
DL8
DL7
DL1
DB0
ADF7020
REGISTER 5--SYNC BYTE REGISTER
Preliminary Technical Data
MATCHING TOLERANCE SYNC BYTE LENGTH
SYNC BYTE SEQUENCE
CONTROL BITS
DB31
DB30
DB29
DB28
DB27
DB26
DB25
DB24
DB23
DB22
DB21
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1 C2(0)
C4(0)
C3(1)
PL2 0 0 1 1
PL1 0 1 0 1
SYNC BYTE LENGTH 12 BITS 16 BITS 20 BITS 24 BITS
MATCHING MT2 MT1 TOLERANCE 0 0 1 1 0 1 0 1 0 ERRORS 1 ERROR 2 ERRORS 3 ERRORS
01975-PrG-033
Figure 33.
Notes: 1. 2. 3. Sync byte detect is enabled by programming Bits R4_DB(25:23) to [010] or [011]. This register allows a 28-bit sync byte sequence to be stored internally. If the sync byte detect mode is selected, then the INT/LOCK pin goes high when the sync byte has been detected in Rx mode. Once the sync word detect signal has gone high, it goes low again after nine data bits. The transmitter must Tx the MSB of the sync byte first and the LSB last to ensure proper alignment in the receiver sync byte detection hardware.
Rev. PrH | Page 32 of 40
C1(1)
MT2
MT1
PL2
PL1
DB0
Preliminary Technical Data
REGISTER 6--CORRELATOR/DEMODULATOR REGISTER
LNA MODE IF FILTER CAL MIXER LINEARITY
Rx RESET
ADF7020
DOT PRODUCT LNA CURRENT
RxDATA INVERT
IF FILTER DIVIDER
DISCRIMINATOR BW
ADDRESS BITS
DB31
DB30
DB29
DB28
DB27
DB26
DB25
DB24
DB23
DB22
DB21
DB20
DB19
DB18
DB17
DB16
DB15
DB14
TD10 DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1 C2(1)
C4(0)
C3(1)
CA1 FILTER CAL DEMOD RESET CDR RESET RxDATA INVERT RxDATA RxDATA 0 1 NO CAL CALIBRATE
DP1 0 1 LG1 0 1 LI2 0 LI1 0 LNA BIAS 800A (DEFAULT)
DOT PRODUCT CROSS PRODUCT DOT PRODUCT LNA MODE DEFAULT REDUCED GAIN
ML1 MIXER LINEARITY 0 1 DEFAULT HIGH
RI1 0 1
FC9 0 0 . . . . 1
. . . . . . . .
FC6 0 0 . . . . 1
FC5 0 0 . . . . 1
FC4 0 0 . . . . 1
FC3 0 0 . . . . 1
FC2 0 1 . . . . 1
FC1 1 0 . . . . 1
FILTER CLOCK DIVIDE RATIO 1 2 . . . . 511
Figure 34.
Notes: 1. 2. 3. 4. 5. See the FSK Correlator/Demodulator section for an example of how to determine register settings. Nonadherence to correlator programming guidelines results in poorer sensitivity. The filter clock is used to calibrate the IF filter. The filter clock divide ratio should be adjusted so that the frequency is 50 kHz. The formula is XTAL/FILTER_CLOCK_DIVIDE. The filter should be calibrated only when the crystal oscillator is settled. The filter calibration is initiated every time Bit R6_DB19 is set high. Discriminator_BW = (DEMOD_CLK x K)/(800 x 103). See the FSK Correlator/Demodulator section.
Rev. PrH | Page 33 of 40
01975-PrG-034
C1(0)
ML1
CA1
LG1
DP1
FC7
FC4
FC3
TD8
TD7
TD6
FC9
FC8
FC2
FC1
TD9
TD5
TD4
FC6
FC5
TD3
TD2
TD1
RI1
LI2
LI1
DB0
ADF7020
REGISTER 7--READBACK SETUP REGISTER
READBACK SELECT DB8 RB3 DB7 RB2 DB6 RB1 ADC MODE DB5 AD2 DB4 AD1 DB3 C4(0)
Preliminary Technical Data
CONTROL BITS DB2 C3(1) DB1 C2(1) DB0 C1(1)
RB3 READBACK 0 1 DISABLED ENABLED RB2 RB1 READBACK MODE 0 0 1 1 0 1 0 1 AFC WORD ADC OUTPUT FILTER CAL SILICON REV
AD2 AD1 ADC MODE 0 0 1 1 0 1 0 1 MEASURE RSSI BATTERY VOLTAGE TEMP SENSOR TO EXTERNAL PIN
01975-PrG-035
Figure 35.
Notes: 1. 2. 3. 4. Readback of the measured RSSI value is valid only in Rx mode. Readback of the battery voltage, the temperature sensor, and the voltage at the external pin is not available in Rx mode, if the ASK demodulator is active or if AGC is enabled. Readback of the ADC value is valid in Tx mode only if the log amp/RSSI has not been disabled through the power-down bits R8_DB10. The log amp/RSSI section is active per default upon enabling Tx mode. Readback of the AFC word is valid in Rx mode only if either the linear demodulator or the correlator/demodulator is active. See the Readback Format section for more information.
Rev. PrH | Page 34 of 40
Preliminary Technical Data
REGISTER 8--POWER-DOWN TEST REGISTER
INTERNAL Tx/Rx SWITCH ENABLE PA ENABLE Rx MODE LNA/MIXER ENABLE DEMOD ENABLE ADC ENABLE FILTER ENABLE VCO ENABLE SYNTH ENABLE
ADF7020
LOG AMP/ RSSI
CONTROL BITS
DB15
DB14
DB13 PD7
DB12 SW1
DB11 LR2
DB10 LR1
DB9 PD6
DB8 PD5
DB7 PD4
DB6 PD3
DB5 PD2
DB4 PD1
DB3 C4(1)
DB2 C3(0)
DB1 C2(0)
DB0 C1(0)
PD9 0 1
PA (Rx MODE) PA OFF PA ON PD4 0 1 Tx/Rx SWITCH DEFAULT (ON) OFF LR2 X X LR1 0 1 RSSI MODE RSSI OFF RSSI ON PD6 0 1 DEMOD ENABLE DEMOD OFF DEMOD ON PD5 0 1 PD4 0 1 ADC ENABLE ADC OFF ADC ON PD3 0 1
PLE1 (FROM REG 0) 0 0 0 0 1
PD2 0 0 1 1 X
PD1 0 1 0 1 X
LOOP CONDITION VCO/PLL OFF PLL ON VCO ON PLL/VCO ON PLL/VCO ON
LNA/MIXER ENABLE LNA/MIXER OFF LNA/MIXER ON
FILTER ENABLE FILTER OFF FILTER ON
01975-PrG-036
Figure 36.
Notes: 1. 2. For a combined LNA/PA matching network, Bit R8_DB12 should always be set to 0. This is the power-up default condition. It is not necessary to write to this register under normal operating conditions.
Rev. PrH | Page 35 of 40
ADF7020
REGISTER 9--AGC REGISTER
DIGITAL TEST IQ FILTER GAIN LNA GAIN
GAIN CONTROL AGC SEARCH FILTER CURRENT
Preliminary Technical Data
AGC HIGH THRESHOLD
AGC LOW THRESHOLD
ADDRESS BITS
DB31
DB30
DB29
DB28
DB27
DB26
DB25
DB24
DB23
DB22
DB21
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1 C2(0)
C4(1)
C3(0)
FI1 0 1
FILTER CURRENT LOW HIGH FG2 0 0 1 1 FG1 0 1 0 1 FILTER GAIN 8 24 72 INVALID
GS1 AGC SEARCH 0 1 AUTO AGC HOLD SETTING GL7 0 0 0 0 . . . 1 1 1 GL6 0 0 0 0 . . . 1 1 1 GL5 0 0 0 0 . . . 1 1 1 GL4 0 0 0 0 . . . 1 1 1 GL3 0 0 0 1 . . . 1 1 1 GL2 0 1 1 0 . . . 0 1 1 GL1 1 0 1 0 . . . 1 0 1
AGC LOW THRESHOLD 1 2 3 4 . . . 61 62 63
GC1 GAIN CONTROL 0 1 AUTO USER
RSSI LEVEL GH7 GH6 GH5 GH4 GH3 GH2 GH1 CODE 0 0 0 0 . . . 1 1 1 0 0 0 0 . . . 0 0 0 0 0 0 0 . . . 0 0 1 0 0 0 0 . . . 1 1 0 0 0 0 1 . . . 1 1 0 0 1 1 0 . . . 1 1 0 1 0 1 0 . . . 0 1 0 1 2 3 4 . . . 78 79 80
LG2 0 0 1 1
LG1 0 1 0 1
LNA GAIN 3 10 30 INVALID
C1(1)
01975-PrG-037
GC1
GH7
GH6
GH5
GH4
GH3
GH2
GH1
GS1
FG2
FG1
LG2
LG1
GL7
GL6
GL5
GL4
GL3
GL2
Figure 37.
Notes : 1. 2. 3. Default AGC_LOW_THRESHOLD = 27, default AGC_HIGH_THRESHOLD = 76. See the RSSI/AGC Section for more details. AGC high and low settings must be more than 30 apart to ensure correct operation. LNA gain of 30 is available only if LNA mode, R6_DB15, is set to zero.
Rev. PrH | Page 36 of 40
GL1
FI1
DB0
Preliminary Technical Data
REGISTER 10--AGC 2 REGISTER
RESERVED UP/DOWN SELECT I/Q SELECT I/Q
ADF7020
I/Q PHASE ADJUST
I/Q GAIN ADJUST
AGC DELAY
LEAK FACTOR
PEAK RESPONSE
ADDRESS BITS
DB31
DB30
DB29
SIQ2 DB28
DB27
DB26
DB25
DB24
DB23
SIQ1 DB22
DB21
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
C4 (1) DB3
C3 (0) DB2
C2 (1) DB1
C1 (0) DB0 C1(0)
01975-PrG-039
GC5
GC4
GC3
GC2
GC1
UD1
DH4
DH3
DH2
DH1
GL7
GL6
GL5
GL4
PH2
PH1
PR2
PH4
PH3
PR4
PR3
PR1
R1
SIQ2 SELECT IQ 0 1 PHASE TO I CHANNEL PHASE TO Q CHANNEL
SIQ2 SELECT IQ 0 1 GAIN TO I CHANNEL GAIN TO Q CHANNEL DEFAULT = 10
DEFAULT = 10 DEFAULT = 2
Figure 38.
Note: 1. This register is not used under normal operating conditions.
REGISTER 11--AFC REGISTER
DB20 AFC ENABLE
CONTROL BITS
AFC SCALING COEFFICIENT
DB31
DB30
DB29
DB28
DB27
DB26
DB25
DB24
DB23
DB22
DB21
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
C4(0)
C3(0)
INTERNAL AE1 AFC 0 1 OFF ON
Figure 39.
Notes: 1. 2. See the Internal AFC section to program AFC scaling coefficient bits. The AFC scaling coefficient bits can be programmed using the following formula: AFC_Scaling_Coefficient = Round((500 x 224)/XTAL)
Rev. PrH | Page 37 of 40
C2(1)
M16
M15
M14
M13
M12
M11
M10
AE1
M9
M8
M7
M6
M5
M4
M3
M2
M1
DB0
01975-PrG-038
ADF7020
REGISTER 12--TEST REGISTER
DB31 PRESCALER OSC TEST COUNTER RESET SOURCE FORCE LD HIGH
- TEST MODES
Preliminary Technical Data
ANALOG TEST MUX
IMAGE FILTER ADJUST
DIGITAL TEST MODES
PLL TEST MODES
ADDRESS BITS
DB30
DB29
DB28
DB27
DB26
DB25
DB24
DB23
DB22
DB21
DB20
DB19
DB18
DB17
DB16
DB15
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1 C2(0)
C4(1)
C3(1)
P 0 1
PRESCALER 4/5 (DEFAULT) 8/9 CS1 0 1 CAL SOURCE INTERNAL SERIAL IF BW CAL
DEFAULT = 32. INCREASE NUMBER TO INCREASE BW IF USER CAL ON
CR1 COUNTER RESET 0 1 DEFAULT RESET
01975-PrG-043
Figure 40.
Using the Test DAC on the ADF7020 to Implement Analog FM DEMOD and Measuring SNR
The test DAC allows the output of the postdemodulator filter for both the linear and correlator/demodulators (Figure 16 and Figure 17) to be viewed externally. It takes the 16-bit filter output and converts it to a high frequency, single-bit output using a second-order error feedback - converter. The output can be viewed on the XCLKOUT pin. This signal, when IF filtered appropriately, can then be used to * Monitor the signals at the FSK/ASK postdemodulator filter output. This allows the demodulator output SNR to be measured. Eye diagrams can also be constructed of the received bit stream to measure the received signal quality. Provide analog FM demodulation.
Programming the test register, Register 12, enables the test DAC. Both the linear and correlator/demodulator outputs can be multiplexed into the DAC. Register 13 allows a fixed offset term to be removed from the signal (to remove the IF component in the ddt case). It also has a signal gain term to allow the usage of the maximum dynamic range of the DAC.
Setting Up the Test DAC
* * Digital test modes = 7: enables the test DAC, with no offset removal. Digital test modes = 10: enables the test DAC, with offset removal.
*
While the correlators and filters are clocked by DEMOD_CLK, CDR_CLK clocks the test DAC. Note that, although the test DAC functions in a regular user mode, the best performance is achieved when the CDR_CLK is increased up to or above the frequency of DEMOD_CLK. The CDR block does not function when this condition exists.
The output of the active demodulator drives the DAC, that is, if the FSK correlator/demodulator is selected, the correlator filter output drives the DAC.
Rev. PrH | Page 38 of 40
C1(0)
PRE
QT1
CS1
SF6
SF5
SF4
SF3
SF2
SF1
T9
T8
T7
T6
T5
T4
T3
T2
T1
DB0
Preliminary Technical Data
REGISTER 13--OFFSET REMOVAL AND SIGNAL GAIN REGISTER
TEST DAC GAIN
DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24
ADF7020
TEST DAC OFFSET REMOVAL
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15
PULSE EXTENSION
DB14 DB13 DB12 DB11 DB10
KI
DB9 DB8 DB7 DB6
KP
DB5 DB4 DB3
CONTROL BITS
DB2 DB1 C2(0) DB0 C1(1)
01975-PrG-044
C4(1)
PE4 0 0 0 . . . 1
PE3 0 0 0 . . . 1
PE2 0 0 1 . . . 1
PE1 0 1 0 . . . 1
PULSE EXTENSION NORMAL PULSE WIDTH 2 x PULSE WIDTH 3 x PULSE WIDTH . . . 16 x PULSE WIDTH
Figure 41.
Note: 1. Because the linear demodulator's output is proportional to frequency, it usually consists of an offset combined with a relatively low signal. The offset can be removed, up to a maximum of 1.0 and gained to use the full dynamic range of the DAC: DAC_input = (2^ Test_DAC_Gain) x (Signal - Test_DAC_Offset_Removal/4096)
Rev. PrH | Page 39 of 40
C3(1)
PE4
PE3
PE2
PE1
ADF7020 OUTLINE DIMENSIONS
0.25 MIN 0.25 MIN PIN 1 INDICATOR 7.00 BSC SQ
37 36
Preliminary Technical Data
48
1
TOP VIEW
0.50 BSC
BO TTOM VIEW
5.25 4.70 SQ 2.25
0.55 0.50 0.45
25 24
12 13
5.50 BSC 1.50 1.45 1.40 0.05 MAX 0.02 NOM SEATING PLANE 0.35 0.20 0.25 COPLANARITY 0.05
Figure 42. 48-Lead Micro Lead Frame Chip Scale Package [MLFCSP] (CP-48M) 7 mm x 7 mm Body Dimensions shown in millimeters
ORDERING GUIDE
Model ADF7020BCP Temperature Range -40C to +85C Package Description 48-Lead Micro Lead Frame Chip Scale Package [MLFCSP] Package Option CP-48M
(c) 2004 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. PR01975-0-6/04(PrH)
Rev. PrH | Page 40 of 40

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