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| 19-1296; Rev 1; 1/98 ANUAL N KIT M LUATIO ATA SHEET EVA WS D FOLLO Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator ____________________________Features o +2.7V to +5.5V Single-Supply Operation o Complete Receive Path: 600MHz (max) 1st IF to 30MHz (max) 2nd IF o Unique, Wide-Dynamic-Range Downconverter Mixer Offers -8dBm IIP3, 11dB NF o 90dB Dynamic-Range Limiter with High-Accuracy RSSI Function o Differential Limiter Output Directly Drives CMOS Input o 100MHz to 600MHz Transmit Quadrature Modulator with 41dB Sideband Suppression o 40dB Transmit Gain-Control Range; Up to +1dBm Output Power o Advanced Power Management (four modes) o 0.2A Shutdown Supply Current ________________General Description The MAX2510 is a highly integrated IF transceiver for digital wireless applications. It operates from a +2.7V to +5.5V supply voltage and features four operating modes for advanced system power management. Supply current is reduced to 0.2A in shutdown mode. In a typical application, the receiver downconverts a high IF/RF (up to 600MHz) to a low IF (up to 30MHz) using a double-balanced mixer. Additional functions included in the receiver section are an IF buffer that can drive an off-chip filter, an on-chip limiting amplifier offering 90dB of received-signal-strength indication (RSSI), and a robust differential limiter output driver designed to directly drive a CMOS input. The transmitter section upconverts I and Q baseband signals to an IF in the 100MHz to 600MHz range using a quadrature modulator. The transmit output is easily matched to drive a SAW filter with an adjustable output from 0dBm to -40dBm and excellent linearity. The MAX2511 has features similar to the MAX2510, but upconverts a low IF with an image-reject mixer. The MAX2511 downconverter also offers image rejection with a limiter/RSSI stage similar to that of the MAX2510. MAX2510 _______________Ordering Information PART MAX2510EEI TEMP. RANGE -40C to +85C PIN-PACKAGE 28 QSOP ________________________Applications PWT1900, Wireless Handsets, and Base Stations PACS, PHS, DECT, and Other PCS Wireless Handsets and Base Stations 400MHz ISM Transceivers IF Transceivers Wireless Data Links ___________________Pin Configuration TOP VIEW LIMIN 1 CZ 2 CZ 3 RSSI 4 GC 5 LO 6 GND 7 28 VREF 27 MIXOUT 26 GND 25 RXIN 24 TXOUT MAX2510 23 TXOUT 22 RXIN 21 VCC 20 GND 19 VCC 18 Q 17 Q 16 I 15 I Typical Operating Circuit appears on last page. VCC 8 LO 9 GND 10 TXEN 11 RXEN 12 LIMOUT 13 LIMOUT 14 QSOP ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator MAX2510 ABSOLUTE MAXIMUM RATINGS VCC to GND .............................................................-0.3V to 8.0V VCC to Any Other VCC ........................................................0.3V I, I, Q, Q to GND .........................................-0.3V to (VCC + 0.3V) I to I, Q to Q Differential Voltage ............................................2V RXIN to RXIN Differential Voltage ..........................................2V LOIN to LOIN Differential Voltage..........................................2V LIMIN Voltage .............................(VREF - 1.3V) to (VREF + 1.3V) RXEN, TXEN, GC Voltage...........................-0.3V to (VCC + 0.3V) RXEN, TXEN, GC Input Current ............................................1mA RSSI Voltage...............................................-0.3V to (VCC + 0.3V) Continuous Power Dissipation (TA = +70C) QSOP (derate 10mW/C above +70C) ........................650mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +165C Lead Temperature (soldering, 10sec) .............................+300C Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS (VCC = +2.7V to +5.5V; 0.01F across CZ and CZ; LO, LO open; MIXOUT tied to VREF through a 165 resistor; GC = 0.5V; RXIN, RXIN open; LIMIN tied through 50 to VREF; LIMOUT, LIMOUT = open; RXEN, TXEN = high; bias voltage at I, I, Q, Q = 1.4V; TA = -40C to +85C; unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Operating Voltage Range Digital Input Voltage High Digital Input Voltage Low Digital Input Current High Digital Input Current Low RXEN, TXEN RXEN, TXEN RXEN, TXEN = 2.0V RXEN, TXEN = 0.4V Receive mode, RXEN = high, TXEN = low Supply Current Transmit mode, RXEN = low, TXEN = high Standby mode, RXEN = high, TXEN = high Shutdown mode, RXEN = low, TXEN = low VREF Voltage GC Input Resistance (Note 1) VCC / 2 100mV 50 -5 6 0.1 14 17 0.5 0.2 VCC / 2 85 20 25 1 5 VCC / 2 + 100mV A V k mA CONDITIONS MIN 2.7 2.0 0.4 30 TYP 3.0 MAX 5.5 UNITS V V V A A AC ELECTRICAL CHARACTERISTICS (MAX2510 test fixture; VCC = +3.0V; RXEN = TXEN = low; 0.01F across CZ and CZ; MIXOUT tied to VREF through 165 resistor; TXOUT and TXOUT loaded with 100 differential; LO terminated with 50, LO AC grounded; GC open; LIMOUT, LIMOUT are AC coupled to 250 load; 330pF at RSSI pin; 0.1F connected from VREF pin to GND; PRXIN, RXIN = -30dBm differentially driven (input matched); fRXIN, RXIN = 240MHz; bias voltage at I, I, Q, Q = 1.4V; VI,Q = 500mVp-p; fI,Q = 200kHz; fLO, LO = 230MHz; PLO = -13dBm; TA = +25C; unless otherwise noted.) PARAMETER DOWNCONVERTER (RXEN = high) Input Frequency Range Conversion Gain Noise Figure Input 1dB Compression Point Input Third-Order Intercept LO to RXIN Isolation Power-Up Time 2 Standby to RX or TX (Note 5) (Note 2) TA = +25C TA = -40C to +85C (Note 3) Single sideband (Note 4) Two tones at 240MHz and 240.2MHz, -30dBm per tone 100 20.5 19.9 11 -18.5 -8 49 5 22.5 600 25 25.5 MHz dB dB dBm dBm dBc s CONDITIONS MIN TYP MAX UNITS _______________________________________________________________________________________ Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator AC ELECTRICAL CHARACTERISTICS (continued) (MAX2510 test fixture; VCC = +3.0V; RXEN = TXEN = low; 0.01F across CZ and CZ; MIXOUT tied to VREF through 165 resistor; TXOUT and TXOUT loaded with 100 differential; LO terminated with 50, LO AC grounded; GC open; LIMOUT, LIMOUT are AC coupled to 250 load; 330pF at RSSI pin; 0.1F connected from VREF pin to GND; PRXIN, RXIN = -30dBm differentially driven (input matched); fRXIN, RXIN = 240MHz; bias voltage at I, I, Q, Q = 1.4V; VI,Q = 500mVp-p; fI,Q = 200kHz; fLO, LO = 230MHz; PLO = -13dBm; TA = +25C; unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS MAX2510 LIMITING AMPLIFIER AND RSSI (RXEN = high, fLIMIN = 10MHz, PLIMIN = -30dBm from 50 source, unless otherwise noted) Limiter Output Voltage Swing Phase Variation Minimum Linear RSSI Range Minimum Monotonic RSSI Range RSSI Slope LIMOUT, LIMOUT -75dBm to 5dBm -75dBm to 5dBm -85dBm to 5dBm -75dBm to 5dBm from 50 TA = +25C TA = -40C to +85C (Note 3) At LIMIN input of -75dBm At LIMIN input of +5dBm 0.25 1.8 270 300 4.5 80 90 20 -86 0.5 2.0 3.0 350 mV degrees dB dB mV/dB dBm dB V V RSSI Maximum Zero-Scale Intercept (Note 6) RSSI Relative Error (Notes 6, 7) Minimum-Scale RSSI Voltage Maximum-Scale RSSI Voltage TRANSMITTER (TXEN = high) Frequency Range I, I, Q, Q Allowable Common-Mode Voltage Range (Note 8) I, I, Q, Q inputs are 250mVp-p centered around this voltage, GC = 2.0V (Note 9) I, Q are 500mVp-p while I, Q are held at this DC voltage (Note 9) GC = 0.5V Output Power GC = open GC = 2.0V (Note 9) I, I, Q, Q 1dB Bandwidth Unwanted Sideband Suppression LO Rejection Output IM3 Level Output IM5 Level (Note 3) 90 phase difference between I and Q inputs; GC = 2V 90 phase difference between I and Q inputs; measured to fundamental tone; GC = 2V GC = 0.5V (Note 11) GC = 2V (Note 11) GC = 2V (Note 11) TA = +25C TA = -40C to +85C -2.5 -3 70 30 30 100 1.3 1.4 600 VCC 1.2 MHz V VCC 1.3 -41 -16 1 80 40 44 -49 -33 -51 dBm MHz dBc dBc dBc dBc Note 1: This pin is internally terminated to approximately 1.35V through the specified resistance. Note 2: Downconverter gain is typically greater than 20dB. Operation outside this frequency range is possible but has not been characterized. Note 3: Guaranteed by design and characterization. _______________________________________________________________________________________ 3 Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator Note 4: Driving RXIN or RXIN with a power level greater than the 1dB compression level forces the input stage out of its linear range, causing harmonic and intermodulation distortion. The RSSI output increases monotonically with increasing input levels beyond the mixer's 1dB compression level. Input 1dB compression point is limited by MIXOUT voltage swing, which is approximately 2Vp-p into a 165 load. Note 5: Assuming the supply voltage has been applied, this includes limiter offset-correction settling and Rx or Tx bias stabilization time. Guaranteed by design and characterization. Note 6: The RSSI maximum zero-scale intercept is the maximum (over a statistical sample of parts) input power at which the RSSI output would be 0V. This point is extrapolated from the linear portion of the RSSI Output Voltage vs. Limiter Input Power graph in the Typical Operating Characteristics. This specification and the RSSI slope define the RSSI function's ideal behavior (the slope and intercept of a straight line), while the RSSI relative error specification defines the deviations from this line. See the Typical Operating Characteristics for the RSSI Output Voltage vs. Limiter Input Power graph. Note 7: The RSSI relative error is the deviation from the best-fitting straight line of the RSSI output voltage versus the limiter input power. This number represents the worst-case deviation at any point along this line. A 0dB relative error is exactly on the ideal RSSI transfer function. The limiter input power range for this test is -75dBm to 5dBm from 50. See the Typical Operating Characteristics for the RSSI Relative Error graph. Note 8: Transmit sideband suppression is typically better than 35dB. Operation outside this frequency range is possible but has not been characterized. Note 9: Output IM3 level is typically better than -29dBc. Note 10: The output power can be increased by raising GC above 2V. Refer to the Transmitter Output Power vs. GC Voltage and Frequency graph in the Typical Operating Characteristics. Note 11: Using two tones at 400kHz and 500kHz, 250mVp-p differential per tone at I, I, Q, Q. MAX2510 __________________________________________Typical Operating Characteristics (MAX2510 EV kit; VCC = +3.0V; 0.01F across CZ and CZ; MIXOUT tied to VREF through 165 resistor; TXOUT and TXOUT loaded with 100 differential; LO terminated with 50; LO AC grounded; GC open; LIMOUT, LIMOUT open; 330pF at RSSI pin; 0.1F connected from VREF pin to GND; PRXIN, RXIN = -30dBm differentially driven (input matched); fRXIN, RXIN = 240MHz; bias voltage at I, I, Q, Q = 1.4V; VI,Q = 500mVp-p; f I, Q = 200kHz; fLO, LO = 230MHz; PLO = -13dBm; TA = +25C; unless otherwise noted.) SUPPLY CURRENT vs. TEMPERATURE MAX2510toc01 SUPPLY CURRENT vs. SUPPLY VOLTAGE Tx 18 16 SUPPLY CURRENT (mA) 14 12 10 8 6 4 Tx Rx MAX2510toc02 TRANSMITTER SUPPLY CURRENT vs. GC VOLTAGE 30 SUPPLY CURRENT (mA) 25 20 15 10 5 MAX2510toc03 25 20 35 20 SUPPLY CURRENT (mA) Rx 15 10 5 STANDBY 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) 2 0 2.5 3.0 3.5 4.0 4.5 STANDBY 0 5.0 5.5 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 GC VOLTAGE (V) SUPPLY VOLTAGE (V) 4 _______________________________________________________________________________________ Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator MAX2510 ____________________________ Typical Operating Characteristics (continued) (MAX2510 EV kit; VCC = +3.0V; 0.01F across CZ and CZ; MIXOUT tied to VREF through 165 resistor; TXOUT and TXOUT loaded with 100 differential; LO terminated with 50; LO AC grounded; GC open; LIMOUT, LIMOUT open; 330pF at RSSI pin; 0.1F connected from VREF pin to GND; PRXIN, RXIN = -30dBm differentially driven (input matched); fRXIN, RXIN = 240MHz; bias voltage at I, I, Q, Q = 1.4V; VI,Q = 500mVp-p; f I, Q = 200kHz; fLO, LO = 230MHz; PLO = -13dBm; TA = +25C; unless otherwise noted.) DOWNCONVERTER MIXER CONVERSION GAIN vs. SUPPLY VOLTAGE AND TEMPERATURE MAX2510toc04 MAX2510toc05 SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE 1.2 SHUTDOWN SUPPLY CURRENT (A) 1.0 0.8 GAIN (dB) TA = +85C 0.6 0.4 0.2 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) TA = +25C 19 18 TA = -40C 25 DOWNCONVERTER MIXER CONVERSION GAIN vs. RXIN FREQUENCY MAX2510toc06 25 TA = -40C 24 23 22 TA = +25C 21 20 TA = +85C 20 GAIN (dB) 15 10 5 MISMATCH LOSS COMPENSATED 0 2.5 3.0 3.5 4.0 VOLTAGE (V) 4.5 5.0 5.5 0 100 200 300 400 500 600 700 800 900 1000 RF FREQUENCY (MHz) RECEIVE MIXER INPUT 1dB COMPRESSION POINT vs. SUPPLY VOLTAGE MAX2510toc07 RXIN INPUT IMPEDANCE vs. FREQUENCY 450 400 REAL IMPEDANCE () 350 300 250 200 150 100 50 0 REAL IMAGINARY SINGLE-ENDED MAX2510toc08 -12 -13 INPUT 1dB COMPRESSION (dBm) -14 -15 -16 -17 -18 -19 -20 -21 -22 2.5 3.0 3.5 4.0 4.5 5.0 TA = -40C TA = +25C TA = +85C 500 5.5 30 90 150 210 270 330 390 450 510 FREQENCY (MHz) SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5 Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator MAX2510 ____________________________ Typical Operating Characteristics (continued) (MAX2510 EV kit; VCC = +3.0V; 0.01F across CZ and CZ; MIXOUT tied to VREF through 165 resistor; TXOUT and TXOUT loaded with 100 differential; LO terminated with 50; LO AC grounded; GC open; LIMOUT, LIMOUT open; 330pF at RSSI pin; 0.1F connected from VREF pin to GND; PRXIN, RXIN = -30dBm differentially driven (input matched); fRXIN, RXIN = 240MHz; bias voltage at I, I, Q, Q = 1.4V; VI,Q = 500mVp-p; f I, Q = 200kHz; fLO, LO = 230MHz; PLO = -13dBm; TA = +25C; unless otherwise noted.) RSSI OUTPUT VOLTAGE vs. LIMIN INPUT POWER AND TEMPERATURE MAX2510toc10a RSSI RELATIVE ERROR vs. LIMIN INPUT POWER AND TEMPERATURE MAX2510toc10 RSSI OUTPUT VOLTAGE vs. RXIN INPUT POWER 1.8 1.6 RSSI VOLTAGE (V) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 MAX2510toc11 2.0 1.8 1.6 RSSI VOLTAGE (V) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 -120 -100 -80 -60 -40 -20 0 VOUT = +85C VOUT = +25C VOUT = -40C 5 4 3 RSSI ERROR (dB) 2 1 0 -1 -2 -3 -4 -5 TA = +85C TA = -40C TA A = +25C T = +25C 2.0 20 -95 -75 -55 -35 -15 5 -80 -70 -60 -50 -40 -30 -20 -10 0 LIMITER INPUT POWER (dBm, 50) LIMITER INPUT POWER (dBm, 50) RXIN INPUT POWER (dBm) TRANSMITTER OUTPUT POWER vs. GC VOLTAGE AND FREQUENCY MAX2510toc12 TRANSMITTER OUTPUT POWER vs. FREQUENCY GC = 2.0V 0 OUTPUT POWER (dBm) -5 -10 -15 -20 -25 MAX2510toc12a 10 0 230MHz OUTPUT POWER (dBm) -10 -20 500MHz -30 200MHz -40 -50 -60 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 GC VOLTAGE (V) 5 0 200 400 600 800 1000 FREQUENCY (MHz) TRANSMITTER IM3 LEVELS vs. GC VOLTAGE MAX2510toc13 TRANSMITTER OUTPUT 1dB COMPRESSION POINT vs. GC VOLTAGE MAX2510toc15 -30 10 OUTPUT 1dB COMPRESSION (dBm) 0 -10 -20 -30 -40 -50 -60 TA = +25C TA = +85C -35 IM3 LEVELS (dBc) -40 -45 TA = -40C -50 -55 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 GC VOLTAGE (V) 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 GC VOLTAGE (V) 6 _______________________________________________________________________________________ Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator MAX2510 ____________________________ Typical Operating Characteristics (continued) (MAX2510 EV kit; VCC = +3.0V; 0.01F across CZ and CZ; MIXOUT tied to VREF through 165 resistor; TXOUT and TXOUT loaded with 100 differential; LO terminated with 50; LO AC grounded; GC open; LIMOUT, LIMOUT open; 330pF at RSSI pin; 0.1F connected from VREF pin to GND; PRXIN, RXIN = -30dBm differentially driven (input matched); fRXIN, RXIN = 240MHz; bias voltage at I, I, Q, Q = 1.4V; VI,Q = 500mVp-p; f I, Q = 200kHz; fLO, LO = 230MHz; PLO = -13dBm; TA = +25C; unless otherwise noted.) TRANSMITTER OUTPUT POWER vs. SUPPLY VOLTAGE MAX2510toc15 OUTPUT POWER vs. BASEBAND INPUT VOLTAGE -12 -14 OUTPUT POWER (dBm) -16 -18 -20 -22 -24 -26 -28 GC = OPEN MAX2510toc16 TRANSMITTER SIDEBAND SUPPRESSION vs. RF FREQUENCY MAX2510toc17 1.0 -10 50 SIDEBAND SUPPRESSION (dB) 0.8 OUTPUT POWER (dBm) TA = +25C 0.6 TA = +85C TA = -40C 40 30 0.4 20 0.2 10 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) -30 50 100 150 200 250 300 350 400 BASEBAND INPUT VOLTAGE (mVp) 0 0 200 400 600 800 1000 RF FREQUENCY (MHz) TRANSMITTER DIFFERENTIAL OUTPUT IMPEDANCE vs. FREQUENCY MAX2510toc18 TRANSMIT NOISE POWER vs. GC VOLTAGE MAX2510toc19 TRANSMITTER OUTPUT POWER vs. LO POWER -13.5 -14.0 OUTPUT POWER (dBm) -14.5 -15.0 -15.5 -16.0 -16.5 -17.0 -17.5 -18.0 MAX2510toc20 100 REAL AND IMAGINARY IMPEDANCE () 0 -100 -200 -300 -400 -500 -600 -700 -800 -900 -1000 -134 -136 OUTPUT NOISE POWER (dBm/Hz) -138 -140 -142 -144 -146 -148 -150 -152 -154 Af = 200kHz -13.0 Tx MODE REAL Tx OFF REAL Tx OFF IMAGINARY Tx MODE IMAGINARY 200 300 400 500 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 GC VOLTAGE (V) -20 -18 -16 -14 -12 -10 -8 LO POWER (dBm) -6 -4 -2 0 FREQUENCY (MHz) _______________________________________________________________________________________ 7 Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator MAX2510 Pin Description PIN 1 2, 3 4 NAME LIMIN CZ, CZ RSSI FUNCTION Limiter Input. Connect a 330 (typical) resistor to VREF for DC bias, as shown in the Typical Operating Circuit. Offset-Correction Capacitor Pins. Connect a 0.01F capacitor between CZ and CZ. Received Signal-Strength Indicator Output. The voltage on RSSI is proportional to the signal power at LIMIN. The RSSI output sources current pulses into a 330pF (typical) external capacitor. This output is internally terminated with 11k, and this RC time constant sets the decay time. Gain-Control Pin. Applying a DC voltage to GC between 0V and 2.0V adjusts the transmitter gain by more than 40dB. GC is internally terminated to 1.35V via an 85k resistor. Differential LO Inputs. In a typical application, externally terminate LO with 50 to ground, then AC couple into LO. AC terminate LO directly to ground for single-ended operation, as shown in the Typical Operating Circuit. Local-Oscillator Input Ground. Connect to PC board ground plane with minimal inductance. Local-Oscillator Input VCC Pin. Bypass directly to local-oscillator input ground (pin 8). Limiter Ground. Connect to PC board ground plane with minimal inductance. Transmitter-Enable Pin. When high, TXEN enables the transmitter if RXEN is low. If both TXEN and RXEN are high, the part is in standby mode; if both are low, the part is in shutdown. See the Power Management section for details. Receiver Enable Pin. When high, RXEN enables the receiver if TXEN is low. If both RXEN and TXEN are high, the part is in standby mode; if both are low, the part is in shutdown. See the Power Management section for details. Differential Outputs of the Limiting Amplifier. These outputs are complementary emitter followers capable of driving 250 single-ended loads to 300mV. Baseband In-Phase Inputs. The differential voltage across these inputs forms the quadrature modulator's I-channel input. The signal input level is typically up to 500mVp-p centered around a 1.4V (typical) DC bias level on I. Baseband Quadrature-Phase Inputs. The differential voltage across these inputs forms the quadrature modulator's Q-channel input. The signal input level is typically up to 500mVp-p, centered around a 1.4V (typical) DC bias level on Q. General-Purpose VCC Pins. Bypass with a 0.047F low-inductance capacitor to GND. Receiver/Transmitter Ground. Connect to PC board ground plane with minimal inductance. Differential Inputs of the Downconverter Mixer. An impedance-matching network may be required in some applications. See the Applications Information section for details. Differential Outputs of the Upconverter. In a typical application, these open-collector outputs are pulled up to VCC with two external inductors and AC coupled to the load. See the Applications Information section for more details, including information on impedance matching these outputs to a load. Receiver Mixer Ground. Connect to PC board ground plane with minimal inductance. Single-Ended Output of the Downconverter Mixer. This pin is high-impedance and must be biased to the VREF pin through an external terminating resistor whose value depends on the interstage filter characteristics. See the Applications Information section for details. Reference Voltage Pin. VREF provides an external bias voltage for the MIXOUT and LIMIN pins. Bypass this pin with a 0.1F capacitor to ground. The VREF voltage is equal to VCC / 2. See the Typical Operating Circuit for more information. 5 GC 6, 9 7 8 10 11 LO, LO GND VCC GND TXEN 12 RXEN LIMOUT, LIMOUT I, I 13, 14 15, 16 17, 18 19, 21 20 22, 25 Q, Q VCC GND RXIN, RXIN TXOUT, TXOUT GND MIXOUT 23, 24 26 27 28 VREF 8 _______________________________________________________________________________________ Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator MAX2510 IF BPF LIMIN MIXOUT VREF CZ OFFSET CORRECTION RXIN gm RXIN LIMOUT VREF = VCC / 2 LO LO RXEN TXEN GC VGA TXOUT PA TXOUT TRANSMIT VGA/PA Q Q RSSI LIMITER LIMOUT CZ RSSI POWER MANAGEMENT I I 0 90 LO PHASE SHIFTER MAX2510 Figure 1. Functional Diagram _______________Detailed Description The following sections describe each of the blocks shown in Figure 1. 330 filter (165 load) to more than 2Vp-p over the entire supply range, providing excellent dynamic range. The local oscillator (LO) input is buffered and drives the mixer. Receiver The receiver consists of two basic blocks: the downconverter mixer and the limiter/received-signal-strength indicator (RSSI) section. The receiver inputs are the RXIN and RXIN pins, which should be AC coupled and may require a matching network as shown in the Typical Operating Circuit. To design a matching network for a particular application, consult the RXIN Input Impedance plots in the Typical Operating Characteristics, as well as the Applications Information sections. Downconverter Mixer The downconverter consists of an a double-balanced mixer and an output buffer. The MIXOUT output, a singleended current source, can drive a shunt-terminated Limiter The signal passes through an external IF bandpass filter into the limiter input (LIMIN). LIMIN is a singleended input that is biased at the VREF pin voltage. The open-circuit input impedance is typically greater than 10k to VREF. For proper operation, LIMIN must be tied to VREF through the filter-terminating impedance (which should be less than 1k). The limiter provides a constant output level, which is largely independent of the limiter input signal level over a 90dB input range. The low-impedance limiter outputs provide 600mVp-p single-ended swing (1.2Vp-p differential swing) and can drive CMOS inputs directly. _______________________________________________________________________________________ 9 Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator Received Signal-Strength Indicator The RSSI output provides a linear indication of the received power level on the LIMIN input. The RSSI monotonic dynamic range exceeds 90dB while providing better than 80dB linear range. The RSSI output pulses current into a 330pF (typical) external filter capacitor. The output is internally terminated to ground with 11k, and this R-C time constant sets the decay time. The rise time is limited by the RSSI pin's output drive current. The rise time is typically less than 100ns with no capacitor connected. Larger capacitor values slow the rise time. MAX2510 0dBm (into 50). Connect a bypass capacitor from LO to ground. Alternatively, a differential LO source (externally terminated) can drive LO and LO through series coupling capacitors. Power Management To provide advanced system power management, the MAX2510 features four operating modes that are selected via the RXEN and TXEN pins, according to Table 1 (supply currents assume GC = 0.5V). In shutdown mode, all part functions are off. Standby mode allows fastest enabling of either transmit or receive mode by keeping the VREF generator active. This avoids delays in stabilizing the limiter input circuitry and the offset correction loop. Transmit mode enables the LO buffer, LO phase shifter, upconverter mixer, transmit VGA, and transmit output driver amplifier. Receive mode enables the LO buffer, downconverter mixer, limiting amplifier, and RSSI functions. Transmitter The I, I and Q, Q baseband signals are input to a pair of double-balanced mixers, which are driven from a quadrature LO source. The quadrature LO is generated on-chip from the oscillator input present at the LO and LO pins. The two mixers' outputs are summed. With quadrature baseband inputs at the I, I and Q, Q pins, the unwanted sideband is largely canceled. The resulting signal from the mixers is fed through a variable-gain amplifier (VGA) with more than 40dB of gain-adjust range. The VGA output is connected to a driver amplifier with an output 1dB compression point of +2dBm. The output power can be adjusted from approximately +2dBm to -40dBm by controlling the GC pin. The resulting signal appears as a differential output on the TXOUT and TXOUT pins. TXOUT and TXOUT are open-collector outputs and need external pull-up inductors to VCC for proper operation, as well as a DC block so the load does not affect DC biasing. A shunt resistor across TXOUT and TXOUT (100 typical) can be used to back terminate an external filter, as shown in the Typical Operating Circuit. Alternatively, a single-ended load can be connected to TXOUT, as long as TXOUT is tied directly to VCC. Refer to the Applications Information section for details. Table 1. Power-Supply Mode Selection RXEN STATE Low Low High High TXEN STATE Low High Low High MODE Shutdown Transmit Receive Standby TYPICAL SUPPLY CURRENT (A) 0.2 17m 14m 0.5m __________Applications Information RX Input Matching The RXIN, RXIN port typically needs an impedance matching network for proper connection to external circuitry, such as a filter. See the Typical Operating Circuit for an example circuit topology. Note that the receiver input can be driven either single-ended or differentially. The component values used in the matching network depend on the desired operating frequency as well as on filter impedance. The following table indicates the RXIN, RXIN single-ended input impedance (that is, the impedance looking into either RXIN or RXIN). The information in Table 2 is also plotted in the Typical Operating Characteristics. Local-Oscillator Inputs The MAX2510 requires an external LO source for the mixers. LO and LO are high-impedance inputs (>1k). The external LO signal is buffered internally and fed to both the receive mixer and the LO phase shifter used for the transmit mixers. In a typical application, externally terminate the LO source with a 50 resistor and then AC couple into LO. Typically, the LO power range should be -13dBm to 10 ______________________________________________________________________________________ Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator Table 2. RXIN or RXIN Input Impedance FREQUENCY (MHz) 100 200 300 400 500 SERIES IMPEDANCE () 275 - j203 149 - j184 94 - j143 64 - j109 53 - j87 noise amplifier (LNA) that can operate over the same supply voltage range. The MAX2630-MAX2633 family of amplifiers meets this requirement. In many applications, the MAX2510's transmit output power is sufficient to eliminate the need for an external power amplifier. MAX2510 ______________________Layout Issues A well-designed PC board is an essential part of an RF circuit. Use the MAX2510 evaluation kit and the recommendations below as guides to generate your own layout. Receive IF Filter The interstage filter, located between the MIXOUT pin and the LIMIN pin, is typically a three-terminal, 330, 10.7MHz bandpass filter. This filter prevents the limiter from acting on any undesired signals that are present at the mixer's output, such as LO feedthrough, out-ofband channel leakage, and spurious mixer products. The filter connections are also set up to feed DC bias from VREF into LIMIN and MIXOUT through two 330 filter-termination resistors. (See the Typical Operating Circuit for more information). Power-Supply Layout A star topology, which has a heavily decoupled central VCC node, is the ideal power-supply layout for minimizing coupling between different sections of the chip. The VCC traces branch out from this node, each going to one VCC connection in the MAX2510 typical operating circuit. At the end of each of these traces is a bypass capacitor that presents low impedance at the RF frequency of interest. This method provides local decoupling at each VCC pin. At high frequencies, any signal leaking out of a supply pin sees a relatively high impedance (formed by the VCC trace impedance) to the central VCC node, and an even higher impedance to any other supply pin, minimizing Vcc supply-pin coupling. A single ground plane suffices. Where possible, multiple parallel vias aid in reducing inductance to the ground plane. Place the VREF decoupling capacitor (0.1F typical) as close to the MAX2510 as possible for best interstage filter performance. For best results, use a high-quality, low-ESR capacitor. Matching/biasing networks around the receive and transmit pins should be symmetric and as close to the chip as possible. A cutout in the ground plane under the matching network components can be used to reduce parasitic capacitance. Decouple pins 19 and 21 (VCC) directly to pin 20 (Rx, Tx ground), which should be directly connected the ground plane. Similarly, decouple pin 8 directly to pin 7. Refer to the Pin Description table for more information. Transmit Output Matching The transmit outputs, TXOUT and TXOUT, are opencollector outputs and therefore present a high impedance. For differential drive, TXOUT and TXOUT are connected to VCC via chokes, and each side is AC coupled to the load. A terminating resistor between TXOUT and TXOUT sets the output impedance. This resistor provides a stable means of matching to the load. TXOUT and TXOUT are voltage-swing limited, and therefore cannot drive the specified maximum power across more than 150 load impedance. This load impedance typically consists of a shunt-terminating resistor in parallel with a filter load impedance. To drive higher output load impedances, the gain must be reduced (via the GC pin) to avoid saturating the TX output stage. For single-ended applications, connect the unused TX output output pin directly to VCC. 400MHz ISM Applications The MAX2510 can be used as a front-end IC in applications where the RF carrier frequency is in the 400MHz ISM band. In this case, Maxim recommends preceding the MAX2510 receiver section with a low- ______________________________________________________________________________________ 11 Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator MAX2510 Typical Operating Circuit VCC 100pF FOR SINGLE-ENDED TX OPERATION 100 220nH VCC 23 TXOUT I I TX OUTPUT (TO FILTER) 0.001F MATCH 10pF FOR SINGLE-ENDED RX OPERATION 22 RXIN 25 RXIN LIMOUT RXEN TXEN VCC LO GNDLO 26 VCC VCC 21 19 0.001F 0.001F 20 27 GND MIXOUT LIMIN 10.7MHz BpF, Z0 = 330 1 VREF 28 CZ 2 0.01F IF BYPASS FILTER 330 330 330pF VCC VCC GC RSSI CZ GND LOIN LOIN GND 6 9 10 5 4 3 RSSI OUTPUT 47pF 5O 47pF FROM LOCAL OSCILLATOR Q 24 TXOUT 15 16 18 17 13 14 12 11 VCC 330pF 8 0.001F 7 CONTROL LOGIC RECEIVE IF OUTPUT BASEBAND Q INPUT BASEBAND I INPUT MAX2510 Q LIMOUT GAIN CONTROL 0.001F 0.1F 12 ______________________________________________________________________________________ |
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