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LT5504 800MHz to 2.7GHz RF Measuring Receiver
FEATURES

DESCRIPTIO
RF Frequency Range: 800MHz to 2.7GHz Ultra Wide Dynamic Range: 75dB at 900MHz Wide Power Supply Range: 2.7V to 5.25V Low Supply Current: 14.7mA at 3V 8-Lead MS0P Package
APPLICATIO S

RSSI Measurements Receive AGC Transmit Power Control ASK and Envelope Demodulation GSM/TDMA/CDMA/WCDMA
The LT(R)5504 is an 800MHz to 2700MHz monolithic integrated measuring receiver, capable of detecting a wide dynamic range RF signal from -75dBm to +5dBm. The logarithm of the RF signal is precisely converted into a linear DC voltage. The LT5504 consists of RF/IF limiters, an LO buffer amplifier, a limiting mixer, a 3rd-order 450MHz integrated low pass filter, RF/IF detectors and an output interface. The ultrawide dynamic range is achieved by simultaneously measuring the RF signal and a downconverted IF signal obtained using the on-chip mixer and an external local oscillator. The RF- and IF-detected signals are summed to generate an accurate linear DC voltage proportional to the input RF voltage (or power) in dB. The output is buffered with a low output impedance driver.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
C2 1nF
C1 100pF
3V
LT5504
VCC
VOUT
OUTPUT VOUT (V) R2 200 C3 10pF
RF INPUT R1 82
RF+
RF DETECTOR
IF DETECTOR
***
IF DETECTOR
RF - ENABLE EN GND LO
5504 TA01a
LO INPUT
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Output Voltage and Slope Variation vs RF Input Power
2.4 2.0 1.6 1.2 0.8 0.4 0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm) fRF = 900MHz fIF = 240MHz AVERAGE SLOPE:23mV/dB 6 4
SLOPE VARIATION (dB)
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2 0 -2 -4 -6 10
0
5504 TA01b
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LT5504
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW VCC RF+ RF - GND 1 2 3 4 8 7 6 5 VCC VOUT LO EN
Power Supply Voltage ............................................ 5.5V VOUT, EN ................................................................ 0,VCC LO Input Power .................................................... 6dBm RF Input Power Differential (50, 5.5V) ............. 24dBm RF Input Power Single-Ended (50, 5.5V) ......... 18dBm Operating Ambient Temperature ..............-40C to 85C Storage Temperature Range ..................-65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
ORDER PART NUMBER LT5504EMS8 MS8 PART MARKING LTGP
MS8 PACKAGE 8-LEAD PLASTIC MSOP
TJMAX = 150C, JA = 160C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL RF Input fRF Frequency Range Input Impedance DC Voltage LO Input fLO Frequency Range Input Return Loss DC Voltage PLO LO Power LO to RF Leakage PARAMETER
TA = 25C. VCC = 3V, PLO = -10dBm, unless otherwise noted. (Notes 2, 3)
MIN TYP 800 to 2700 MAX UNITS MHz V MHz dB V dBm dBc dBc dBc MHz dB V V V mV/dB dB V V V mV/dB
CONDITIONS
(Note 6) Internally Biased 1.7 850 to 3100 Internally Matched to 50 Internally Biased 900MHz 1.9GHz 2.5GHz 14 0.82 -16 to -8 -50 -45 -40 50 to 450 66 Input = -70dBm Input = -20dBm Input = 0dBm Input from -50dBm to -20dBm 16 60 Input = -70dBm Input = -20dBm Input = 0dBm Input from -50dBm to -20dBm 16 75 0.4 1.6 2.1 23 72 0.35 1.52 1.9 23
IF Frequency fIF Frequency Linear Dynamic Range (Note 4) Output Voltage Output Voltage at fRF = 900MHz, fLO = 1140MHz
Average Slope Output Voltage at fRF = 1900MHz, fLO = 2140MHz Linear Dynamic Range (Note 4) Output Voltage
Average Slope
2
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LT5504
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER Linear Dynamic Range (Note 4) Output Voltage Output Voltage at fRF = 2500MHz, fLO = 2260MHz
TA = 25C. VCC = 3V, PLO = -10dBm, unless otherwise noted. (Notes 2, 3)
MIN 58 TYP 70 0.3 1.45 1.8 16 23 400 MAX UNITS dB V V V mV/dB A V/Hz V/Hz ns ns s k V V 5.25 14.7 22 30 V mA A
CONDITIONS
Input = -70dBm Input = -20dBm Input = 0dBm Input from -50dBm to -20dBm
Average Slope Output Interface Current Drive Capability Output Noise Spectral Density Output Response Time (Note 5) Power Up/Down tON Turn ON Time (Note 5) Turn OFF Time (Note 5) Input Resistance Enable Turn ON Voltage (Note 7) Disable Turn OFF Voltage (Note 7) Power Supply VCC ICC Supply Voltage Supply Current Shutdown Current
At 100KHz At 10MHz RF Input Pin from No Signal to 0dBm
3.9 0.32 200 400 4 30 0.6 * VCC 0.4 * VCC 2.7
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Tests are performed as shown in the configuration of Figure 5. Note 3: Specifications over the -40C to 85C temperature range are guaranteed by design, characterization and correlation with statistical process controls.
Note 4: The Linear Dynamic Range is defined as the range over which the output slope is at least 50% of the average slope from -50dBm to -20dBm. Note 5: The output voltage is settled to the full specification within 1dB. Note 6: Refer to Figure 1 and Applications Information. Note 7: Refer to Pin Functions description.
TYPICAL PERFOR A CE CHARACTERISTICS
Output Voltage vs RF Input Power and Frequency
2.4 fIF = 240MHz 2.0
SUPPLY CURRENT (mA) 18 16 14 TA = -40C 12 TA = 85C 20
1.6 VOUT (V) fRF = 900MHz 1.2 0.8 0.4 0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm) fRF = 1.9GHz
fRF = 2.5GHz
UW
0
5504 G01
Supply Current vs Supply Voltage and Temperature
Power Up Response Time
VCC = 3V RF INPUT POWER = 0dBm VOUT 1V/DIV
TA = 25C
ON ENABLE 1V/DIV
10 8
OFF
10
2.5
3.0
3.5 4.0 4.5 SUPPLY VOLTAGE (V)
5.0
5.5
5504 G02
2s/DIV
5504 G03
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LT5504 TYPICAL PERFOR A CE CHARACTERISTICS
Output Slope Variation vs RF Input Power and Frequency
6 4 SLOPE VARIATION (dB) 2 0 fRF = 1.9GHz -2 -4 50% VARIATION OR SLOPE = 11.5mV/dB fRF = 2.5GHz -6 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm) 0 10 fIF = 240MHz AVERAGE SLOPE: 23mV/dB
2.4 2.0 1.6
VOUT (V)
VOUT (V)
fRF = 900MHz
Output Voltage and Slope Variation vs RF Input Power and Temperature, fIF = 240MHz
2.4 2.0 1.6 fRF = 1.9GHz AVERAGE SLOPE: 23mV/dB 6 4 2.4 2.0
VOUT (V)
1.2 0.8 0.4 TA = 25C 0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm) 0 TA = 85C TA = -40C
0 -2 -4 -6 10
VOUT (V)
1.2 70MHz 400MHz 0.8 0.4 fIF = 400MHz 0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm) 0 fIF = 240MHz
0 -2 -4 -6 10
VOUT (V)
TA = 25C
TA = -40C
Output Voltage and Slope Variation vs RF Input Power and Temperature, fIF = 70MHz
2.4 2.0 1.6 6 fRF = 1.9GHz AVERAGE SLOPE: 23mV/dB 4
VOUT (V)
VOUT (V)
TA = 25C
TA = -40C 0
1.2 0.8 0.4 TA = 85C TA = 25C TA = -40C 0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm) 0
4
UW
5504 G04
(VCC = 3V unless otherwise noted). Output Voltage and Slope Variation vs RF Input Power and Temperature, fRF = 2.5GHz
2.4 2.0
SLOPE VARIATION (dB)
Output Voltage and Slope Variation vs RF Input Power and Temperature, fRF = 900MHz
fIF = 240MHz AVERAGE SLOPE: 23mV/dB 6 4 2 0 TA = 85C 0.8 TA = 25C 0.4 TA = -40C TA = -40C 0 -2 10 0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm) -4 -2
fIF = 240MHz AVERAGE SLOPE: 23mV/dB
6 4
SLOPE VARIATION (dB)
TA = 25C
1.6 TA = 25C 1.2 TA = 85C 0.8 TA = 25C 0.4 TA = -40C TA = -40C 0 0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm)
2 0 -2 -4 -6 10
1.2
5504 G05
5504 G06
Output Voltage and Slope Variation vs RF Input Power and IF Frequency
6 fRF = 1.9GHz AVERAGE SLOPE: 23mV/dB fIF = 70MHz 4
Output Voltage and Slope Variation vs RF Input Power and Supply Voltage
2.4 2.0 SLOPE VARIATION (dB) 1.6 VCC = 5.25V 1.2 0.8 0.4 VCC = 2.7V VCC = 2.7V 0 -2 -4 -6 10 6 fRF = 1.9GHz fIF = 240MHz VCC = 5.25V 4
SLOPE VARIATION (dB)
SLOPE VARIATION (dB) SLOPE VARIATION (dB)
2
1.6 240MHz
2
2
5504 G07
5504 G08
0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm)
0
5504 G09
Output Voltage and Slope Variation vs RF Input Power and Temperature, fIF = 400MHz
2.4 2.0 1.6 1.2 TA = 85C 0.8 TA = 25C 0.4 -4 TA = -40C 0 -6 10 -2 fRF = 1.9GHz AVERAGE SLOPE: 23mV/dB 6 4 SLOPE VARIATION (dB) 2 TA = -40C 0
VOUT 1V/DIV
Output Response Time
2
TA = 25C
-2 -4 -6 10
PULSED RF 900MHz 0dBm 1V/DIV 100ns/DIV
5504 G12
5504 G10
0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm)
5504 G11
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LT5504
PI FU CTIO S
VCC (Pins 1, 8 ): Power Supply Pins. These pins must be tied together at the part as close as possible, and should be decoupled using 1000pF capacitors. RF+ (Pin 2): Positive RF Input Pin. RF- (Pin 3): Negative RF Input Pin. GND (Pin 4): Ground Pin. EN (Pin 5): Enable Pin. The on/off threshold voltage is about VCC/2. When the input voltage is higher than 0.6 * VCC, the circuit is completely turned on. When the input voltage is less than 0.4 * VCC, the circuit is turned off. LO (Pin 6): Local Oscillator Input Pin. VOUT (Pin 7): Output Pin.
BLOCK DIAGRA
RF+ RF-
2 3
APPLICATIO S I FOR ATIO
The LT5504 consists of the following sections: RF/IF limiters, limiting mixer, RF/IF detectors, LO buffer amplifier, 3rd-order integrated low pass filter (LPF), output interface and bias circuitry. An RF signal ranging from 800MHz to 2.7GHz is detected by the RF and IF detectors using a proprietary technique. The down-converted IF signal is band limited by the onchip LPF, reducing broadband noise, and thus an ultrawide dynamic range signal can be measured. The RF measuring receiver is essentially a logarithmic voltage detector. The measured output voltage is directly proportional to the RF signal voltage. An internal temperature compensation circuit results in a highly temperature-stable output voltage.
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VCC 1
VCC 8
7
VOUT
+
DET LIMITING MIXER RF LIMITER LPF IF LIMITER *** IF LIMITER DET DET DET
LO BUFFER
ENABLE
6 LO
4 GND
5 EN
5504 BD
RF Limiter The differential input impedance of the RF limiter is shown in Figure 1. A 1:1 input transformer can be used to achieve 50 broadband matching with an 82 shunt resistor (R1) at the inputs as shown in Figure 5. The 1:1 RF input transformer can also be replaced with a narrow band single-ended-to-differential conversion circuit using three discrete elements as shown in Figure 2. Their nominal values are listed in Table 1. Due to the parasitics of the PCB, these values may require adjustment.
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LT5504
APPLICATIO S I FOR ATIO U
2.5 fRF = 1.9GHz 2.0 WITH SINGLE-ENDED-TODIFFERENTIAL INPUT CIRCUIT VOUT (V) 1.5 1.0 WITH 1:1 INPUT TX
3
1:
63.56 -j98.05 900.00MHz 2: 26.69 -j42.90 1.90GHz 3: 28.88 -j27.76 2.50GHz
2
START: 100MHz
Figure 1. Differential RF Input Impedance
MATCHING NETWORK CS1 3.3pF RF INPUT LSH 3.3nH TO RF -
5504 F02
CS2 3.3pF
Figure 2. RF Input Matching Network at 1900MHz
Figure 3 shows the output voltage vs RF input power response for these two input terminations. The voltage gain of the single-ended-to-differential conversion circuit is:
GAIN = 20 * LOG RIN = 3dB, 50
where RIN = 100 is the narrow band input impedance. Thus, the output voltage curve in this case is shifted to the left by about 3dB.
Table 1. The Component Values of Matching Network LSH, CS1 and CS2
fIF (MHz) 900 1900 2500 2700 LSH(nH) 12.0 3.3 2.7 2.4 CS1/CS2(pF) 3.9 3.3 2.2 1.5
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0.5
0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm)
STOP:3GHz
5504 F01
0
10
5504 F03
Figure 3. The Output Voltage vs RF Input Power
Limiting Mixer and LPF The amplified RF signal is down-converted using the limiting mixer and LO signal. The resulting signal is filtered by the 3rd-order, 450MHz, integrated low pass filter (LPF). Only the desired IF signal is passed to the IF limiters for further detection. Any other mixing products, including LO feedthrough, are much reduced to maximize sensitivity. The receiver's sensitivity is thus defined by the LPF bandwidth. IF Limiter The IF signal is then amplified through the multiple limiter stages for further signal detection. All DC offsets, including LO signal self-mixing, are eliminated by an internal DC offset cancellation circuit. Nevertheless, care should be taken in component placement and in PCB layout to minimize LO coupling to the RF port. Output Interface The output interface of the LT55O4 is shown in Figure 4. The output currents from the RF and IF detectors are summed and converted into an output voltage, VOUT. The maximum charging current available to the output load is about 400A. An internal compensation capacitor CC is used to guarantee stable operation for a large capacitive output load. The slew rate is 80V/s and the small signal output bandwidth is approximately 5MHz when the output is resistively terminated. When the output is loaded with a large capacitor CL, the slew rate is limited
5504f
TO RF +
LT5504
APPLICATIO S I FOR ATIO
to 400A/CL. For example, the slew rate is reduced to 4V/ s when CL = 100pF.
VCC 400A CC VOUT
+ - OUTPUT CURRENTS FROM RF AND IF DETECTORS
5504 F04
Figure 4. Simplified Circuit Schematic of the Output Interface
TYPICAL APPLICATIO S
C2 100pF C1 RF INPUT 100pF 1 C3 1nF VCC R3 10k JUMPER R2 200 VOUT LO INPUT C7 100pF R4 20k
5504 F04
C4 1nF
R1 82 T1 TOKO 617DB-1022
8 VCC VCC LT5504 2 7 RF + VOUT 3 4 RF - GND LO EN 6 5
R5 500k
Figure 5. LT5504 Evaluation Board Circuit Schematic
Figure 7. Component Side Layout of Evaluation Board
Figure 8.Bottom Side Silkscreen of Evaluation Board
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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Applications The LT5504 can be used as a self-standing signal strengthmeasuring receiver (RSSI) for a wide range of input signals from - 75dBm to +5dBm, for frequencies from 800MHz to 2.7GHz. The LT5504 can be used as a demodulator for AM and ASK modulated signals with data rates up to 5MHz. Depending on specific application needs, the RSSI output can be split into two branches, providing AC coupled data output, and DC coupled, RSSI output for signal strength measurements and AGC. Refer to Figure 5. The LT5504 can also be used as a wide range RF power detector for transmit power control.
Figure 6.Component Side Silkscreen of Evaluation Board Figure 9. Bottom Side Layout of Evaluation Board
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PACKAGE DESCRIPTIO U
MS8 Package 8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660)
0.889 0.127 (.035 .005)
3.00 0.102 (.118 .004) (NOTE 3) 8 7 65 0.52 (.206) REF 0.254 (.010)
GAUGE PLANE DETAIL "A" 0 - 6 TYP
5.23 (.206) MIN
3.2 - 3.45 (.126 - .136)
4.88 0.1 (.192 .004)
3.00 0.102 (.118 .004) NOTE 4
0.42 0.04 (.0165 .0015) TYP
0.65 (.0256) BSC
1 0.53 0.015 (.021 .006)
DETAIL "A"
23
4 0.86 (.34) REF
RECOMMENDED SOLDER PAD LAYOUT
0.18 (.077)
NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
1.10 (.043) MAX
SEATING PLANE
0.22 - 0.38 (.009 - .015)
0.65 (.0256) BCS
0.13 0.05 (.005 .002)
MSOP (MS8) 1001
RELATED PARTS
PART NUMBER DESCRIPTION LT5500 LT5502 LT5503 LTC5505 LT5506 LTC5507 LTC5508 LTC5509 LT5511 LT5512 LT5515 LT5516 LT5522 LTC5532 Receiver Front End 400MHz Quadrature Demodulator with RSSI 1.2GHz to 2.7GHz Direct IQ Modulator and Upconverting Mixer 300MHz to 3.5GHz RF Power Detector 500MHz Quadrature IF Demodulator with VGA 100kHz to 1GHz RF Power Detector 300MHz to 7GHz RF Power Detector 300MHz to 3GHz RF Power Detector High Signal Level Upconverting Mixer High Signal Level Downconverting Mixer 1.5GHz to 2.5GHz Direct Conversion Demodulator 600MHz to 2.7GHz High Signal Level Mixer 300MHz to 7GHz Precision RF Power Detector COMMENTS Dual LNA Gain Settling 13.5dB/-14dB at 2.5GHz, Double Balanced Mixer, 1.8V VSUPPLY 5.25V 1.8V to 5.25V Supply, 70MHz to 400MHz IF, 84dB Limiting Gain, 90dB RSSI Range 1.8V to 5.25V Supply, Four-Step RF Power Control, 120MHz Modulation Bandwidth >40dB Dynamic Range, Temperature Compensated, 2.7V to 6V Supply 1.8V to 5.25V Supply, 40MHz to 500MHz IF, -4dB to 57dB Linear Power Gain 48dB Dynamic Range, Temperature Compensated, 2.7V to 6V Supply 44dB Dynamic Range, Temperature Compensated, SC70 Package 36dB Dynamic Range, SC70 Package RF Output to 3GHz, 17dBm IIP3, Integrated LO Buffer DC-3GHz, 20dBm IIP3, Integrated LO Buffer 20dBm IIP3, Integrated LO Quadrature Generator 25dBm IIP3 at 900MHz, 21.5dBm IIP3 at 1.9GHz, Matched 50 RF and LO Ports, Integrated LO Buffer Precision VOUT Offset Control, Adjustable Gain and Offset Voltage
0.8GHz to 1.5GHz Direct Conversion Quadrature Demodulator 21.5dBm IIP3, Integrated LO Quadrature Generator
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 FAX: (408) 434-0507
LT/TP 0305 500 * PRINTED IN USA
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2002

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