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Final Electrical Specifications
LT5504 800MHz to 2.7GHz RF Measuring Receiver
January 2002
FEATURES
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DESCRIPTIO
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RF Frequency Range: 800MHz to 2.7GHz Ultra Wide Dynamic Range: 80dB Over Full Frequency Range and Over Temperature Wide Power Supply Range: 2.7V to 5.25V Low Supply Current: 14.7mA at 3V Shutdown Current: 0.2A 8-Lead MS0P Package
APPLICATIO S
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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
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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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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0
5504 TA01b
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LT5504
ABSOLUTE
(Note 1)
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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 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
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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 0.2 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.
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LT5504 TYPICAL PERFOR A CE CHARACTERISTICS
Output Voltage vs RF Input Power and Frequency
2.4 fIF = 240MHz 2.0
SUPPLY CURRENT (mA)
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
Output Slope Variation vs RF Input Power and Frequency
6 4 fIF = 240MHz AVERAGE SLOPE: 23mV/dB 2.4 2.0 1.6
SLOPE VARIATION (dB)
2 0 fRF = 1.9GHz -2 -4
VOUT (V)
VOUT (V)
fRF = 900MHz
50% VARIATION OR SLOPE = 11.5mV/dB
fRF = 2.5GHz -6 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm)
Output Voltage and Slope Variation vs RF Input Power and Temperature
2.4 fRF = 1.9GHz fIF = 240MHz 2.0 AVERAGE SLOPE: 23mV/dB 1.6
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
4
UW
0 10
5504 G01
Supply Current vs Supply Voltage and Temperature
20 18 16 14 TA = -40C 12
ENABLE 1V/DIV
Power Up Response Time
VCC = 3V RF INPUT POWER = 0dBm VOUT 1V/DIV
TA = 85C
TA = 25C
ON
10 8
OFF
2.5
3.0
3.5 4.0 4.5 SUPPLY VOLTAGE (V)
5.0
5.5
5504 G02
2s/DIV
5504 G03
Output Voltage and Slope Variation vs RF Input Power and Temperature
fRF = 900MHz fIF = 240MHz AVERAGE SLOPE: 23mV/dB 6 4
Output Voltage and Slope Variation vs RF Input Power and Temperature
2.4 fRF = 2.5GHz fIF = 240MHz 2.0 AVERAGE SLOPE: 23mV/dB
SLOPE VARIATION (dB)
6 4
SLOPE VARIATION (dB)
TA = 25C
2 0
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 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 -4 -2 10
0
10
5504 G04
5504 G05
5504 G06
Output Voltage and Slope Variation vs RF Input Power and IF Frequency
2.4 2.0 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)
6 4
SLOPE VARIATION (dB)
2
1.6 240MHz
2
2
0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm)
0
5504 G07
5504 G08
5504 G09
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LT5504 TYPICAL PERFOR A CE CHARACTERISTICS
Output Voltage and Slope Variation vs RF Input Power and Temperature
2.4 6 4
SLOPE VARIATION (dB)
fRF = 1.9GHz fIF = 70MHz 2.0 AVERAGE SLOPE: 23mV/dB 1.6
VOUT (V)
1.2 0.8 0.4 TA = 85C TA = 25C TA = -40C 0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm) 0
0 -2 -4 -6 10
VOUT (V)
TA = 25C
TA = -40C
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
RF LIMITER
UW
5504 G10
Output Voltage and Slope Variation vs RF Input Power and Temperature
2.4 fRF = 1.9GHz fIF = 400MHz 2.0 AVERAGE SLOPE: 23mV/dB 1.6 1.2 TA = 85C 0.8 TA = 25C 0.4 -4 TA = -40C 0 -6 10 -2 6 4 2 TA = -40C 0 VOUT 1V/DIV
Output Response Time
SLOPE VARIATION (dB)
2
TA = 25C
PULSED RF 900MHz 0dBm 1V/DIV 100ns/DIV
5504 G12
0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm)
5504 G11
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VCC 1
VCC 8
7
VOUT
+
DET LIMITING MIXER LPF IF LIMITER *** IF LIMITER DET DET DET
LO BUFFER
ENABLE
6 LO
4 GND
5 EN
5504 BD
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LT5504
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. 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.
1:
63.56 -j98.05 900.00MHz 2: 26.69 -j42.90 1.90GHz 3: 28.88 -j27.76 2.50GHz
3
1 2
START: 100MHz
STOP:3GHz
5504 F01
VOUT (V)
Figure 1. Differential RF Input Impedance
0.5
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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MATCHING NETWORK CS1 3.3pF RF INPUT LSH 3.3nH TO RF -
5504 F02
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TO RF +
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
2.5 fRF = 1.9GHz 2.0 WITH SINGLE-ENDED-TODIFFERENTIAL INPUT CIRCUIT 1.5
LSH(nH) 12.0 3.3 2.7 2.4
CS1/CS2(pF) 3.9 3.3 2.2 1.5
1.0 WITH 1:1 INPUT TX
0 -80 -70 -60 -50 -40 -30 -20 -10 PIN (dBm)
0
10
5504 F03
Figure 3. The Output Voltage vs RF Input Power
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APPLICATIO S I FOR ATIO
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
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
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is loaded with a large capacitor CL, the slew rate is limited 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
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Figure 4. Simplified Circuit Schematic of the Output Interface
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
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LT5504
TYPICAL APPLICATIO
Figure 7. Component Side Layout of Evaluation Board
PACKAGE DESCRIPTIO
0.889 0.127 (.035 .005)
5.23 (.206) MIN
3.2 - 3.45 (.126 - .136)
0.42 0.04 (.0165 .0015) TYP
0.65 (.0256) BSC
RECOMMENDED SOLDER PAD LAYOUT DETAIL "A" 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
RELATED PARTS
PART NUMBER LT5500 LT5502 LT5503 LTC5505 DESCRIPTION 1.8GHz to 2.7GHz Receiver Front End 400MHz Quadrature IF Demodulator with RSSI 1.2GHz to 2.7GHz Direct IQ Modulator and Mixer RF Power Detector in SOT-23 COMMENTS LNA with Dual Gain Setting, Double Balanced Mixer, Internal LO Buffer, 1.8V to 5.25V IF Frequency Range, 70MHz to 400MHz, 84dB Limiting IF Gain 90db Linear RSSI Range, 1.8V to 5.25V Supply 1.8V to 5.25V Supply Range, 28mA Supply Current, 4-Step Output Power Control Internal Schottky Diode with Buffer, >40dB Dyamic Range, Low 0.5mA Supply Current, 2.7V VCC 6V, 300MHz to 3GHz
5504i LT/TP 0102 1.5K * PRINTED IN USA
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507
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Figure 8.Bottom Side Silkscreen of Evaluation Board Figure 9. Bottom Side Layout of Evaluation Board MS8 Package 8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660)
3.00 0.102 (.118 .004) (NOTE 3) 0.52 (.206) REF 8 7 65 0.254 (.010) GAUGE PLANE 0.53 0.015 (.021 .006) 1 1.10 (.043) MAX 23 4 0.86 (.34) REF DETAIL "A" 0 - 6 TYP 4.88 0.1 (.192 .004) 3.00 0.102 (.118 .004) NOTE 4 SEATING PLANE 0.22 - 0.38 (.009 - .015) 0.65 (.0256) BCS 0.13 0.05 (.005 .002)
MSOP (MS8) 1001
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2002

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