LT5504 - 800MHz to 2.7GHz RF Measuring Receiver

LT5504
800MHz to 2.7GHz
RF Measuring Receiver
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DESCRIPTIO
FEATURES
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The LT®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.
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
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APPLICATIO S
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RSSI Measurements
Receive AGC
Transmit Power Control
ASK and Envelope Demodulation
GSM/TDMA/CDMA/WCDMA
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATIO
C2
1nF
3V
C1
100pF
Output Voltage and Slope
Variation vs RF Input Power
VCC
LT5504
2.0
RF
DETECTOR
IF
DETECTOR
•••
IF
DETECTOR
4
OUTPUT
R2
200Ω
C3
10pF
R1
82Ω
VOUT (V)
RF+
fRF = 900MHz
fIF = 240MHz
AVERAGE SLOPE:23mV/dB
1.6
2
1.2
0
0.8
–2
0.4
–4
SLOPE VARIATION (dB)
VOUT
RF
INPUT
6
2.4
RF –
ENABLE
LO
EN
GND
5504 TA01a
LO
INPUT
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
0
–6
10
5504 TA01b
5504f
1
LT5504
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ABSOLUTE
AXI U RATI GS
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PACKAGE/ORDER I FOR ATIO
(Note 1)
Power Supply Voltage ............................................ 5.5V
VOUT, EN ................................................................ 0,VCC
LO Input Power .................................................... 6dBm
RF Input Power Differential (50Ω, 5.5V) ............. 24dBm
RF Input Power Single-Ended (50Ω, 5.5V) ......... 18dBm
Operating Ambient Temperature ..............–40°C to 85°C
Storage Temperature Range ..................–65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
TOP VIEW
VCC
RF+
RF –
GND
1
2
3
4
8
7
6
5
VCC
VOUT
LO
EN
LT5504EMS8
MS8 PACKAGE
8-LEAD PLASTIC MSOP
MS8 PART MARKING
LTGP
TJMAX = 150°C, θJA = 160°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
TA = 25°C. VCC = 3V, PLO = –10dBm, unless otherwise noted. (Notes 2, 3)
CONDITIONS
MIN
TYP
MAX
UNITS
RF Input
fRF
Frequency Range
800 to 2700
Input Impedance
(Note 6)
DC Voltage
Internally Biased
1.7
MHz
V
LO Input
fLO
PLO
Frequency Range
850 to 3100
Input Return Loss
Internally Matched to 50Ω
DC Voltage
Internally Biased
LO Power
LO to RF Leakage
900MHz
1.9GHz
2.5GHz
MHz
14
dB
0.82
V
–16 to –8
dBm
–50
–45
–40
dBc
dBc
dBc
50 to 450
MHz
IF Frequency
fIF
Frequency
Output Voltage at fRF = 900MHz, fLO = 1140MHz
Linear Dynamic Range (Note 4)
66
Output Voltage
Input = –70dBm
Input = –20dBm
Input = 0dBm
Average Slope
Input from –50dBm to –20dBm
16
75
dB
0.4
1.6
2.1
V
V
V
23
mV/dB
72
dB
0.35
1.52
1.9
V
V
V
Output Voltage at fRF = 1900MHz, fLO = 2140MHz
Linear Dynamic Range (Note 4)
60
Output Voltage
Input = –70dBm
Input = –20dBm
Input = 0dBm
Average Slope
Input from –50dBm to –20dBm
16
23
mV/dB
5504f
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LT5504
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
TA = 25°C. VCC = 3V, PLO = –10dBm, unless otherwise noted. (Notes 2, 3)
CONDITIONS
MIN
TYP
MAX
UNITS
58
70
dB
0.3
1.45
1.8
V
V
V
Output Voltage at fRF = 2500MHz, fLO = 2260MHz
Linear Dynamic Range (Note 4)
Output Voltage
Input = –70dBm
Input = –20dBm
Input = 0dBm
Average Slope
Input from –50dBm to –20dBm
16
23
mV/dB
400
µA
Output Interface
Current Drive Capability
Output Noise Spectral Density
At 100KHz
At 10MHz
3.9
0.32
µV/√Hz
µV/√Hz
Output Response Time (Note 5)
RF Input Pin from No Signal to 0dBm
200
ns
Turn ON Time (Note 5)
400
ns
Turn OFF Time (Note 5)
4
µs
Input Resistance
30
kΩ
Power Up/Down
tON
Enable Turn ON Voltage (Note 7)
0.6 • VCC
V
Disable Turn OFF Voltage (Note 7)
0.4 • VCC
V
Power Supply
VCC
Supply Voltage
ICC
Supply Current
2.7
5.25
14.7
Shutdown Current
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 –40°C to 85°C temperature range are
guaranteed by design, characterization and correlation with statistical
process controls.
V
22
mA
30
µA
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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TYPICAL PERFOR A CE CHARACTERISTICS
Output Voltage
vs RF Input Power and Frequency
Supply Current vs Supply Voltage
and Temperature
Power Up Response Time
20
2.4
fIF = 240MHz
VOUT (V)
1.6
fRF = 900MHz
1.2
0.8
fRF = 1.9GHz
fRF = 2.5GHz
16
VOUT
1V/DIV
TA = 25°C
14
ON
TA = –40°C
12
ENABLE
1V/DIV
10
0.4
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
SUPPLY CURRENT (mA)
2.0
VCC = 3V
RF INPUT POWER = 0dBm
TA = 85°C
18
8
0
10
5504 G01
OFF
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
2µs/DIV
5504 G03
5504 G02
5504f
3
LT5504
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TYPICAL PERFOR A CE CHARACTERISTICS
Output Voltage and Slope Variation
vs RF Input Power and Temperature,
fRF = 900MHz
2.4
fIF = 240MHz
AVERAGE SLOPE: 23mV/dB
2.0
4
1.6
VOUT (V)
0
fRF = 1.9GHz
50% VARIATION OR
SLOPE = 11.5mV/dB
–4
0
1.2
TA = 85°C
–2
TA = 25°C
TA = –40°C
0
5504 G04
Output Voltage and Slope Variation
vs RF Input Power and Temperature,
fIF = 240MHz
6
fRF = 1.9GHz
AVERAGE SLOPE: 23mV/dB
VOUT (V)
0
1.2
0.8
TA = 85°C
–2
TA = –40°C
–4
0.4
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
5504 G05
2.4
2
0
400MHz
0.8
fIF = 240MHz
–2
0
–6
10
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
5504 G07
0
1.2
VCC = 2.7V
0.8
Output Voltage and Slope Variation
vs RF Input Power and Temperature,
fIF = 400MHz
–2
VCC = 2.7V
–4
4
1.6
2
1.6
2
1.2
TA = 85°C
–2
TA = 25°C
–4
TA = –40°C
0
–6
10
5504 G10
VOUT (V)
0
fRF = 1.9GHz
AVERAGE SLOPE: 23mV/dB
TA = 25°C
TA = –40°C
0
1.2
TA = 85°C
–2
0.8
TA = 25°C
0.4
–4
TA = –40°C
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
–6
10
5504 G09
Output Response Time
0
–6
10
5504 G11
SLOPE VARIATION (dB)
2.0
TA = –40°C
0
6
4
fRF = 1.9GHz
AVERAGE SLOPE: 23mV/dB
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
2
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
5504 G08
2.0
0.4
4
VCC = 5.25V
VCC = 5.25V
0.4
–6
10
0
2.4
0.8
6
1.6
–4
6
TA = 25°C
5504 G06
fRF = 1.9GHz
fIF = 240MHz
2.0
240MHz
1.2 70MHz
–6
10
0
Output Voltage and Slope Variation
vs RF Input Power and Supply Voltage
4
1.6
TA = –40°C
fIF = 400MHz
SLOPE VARIATION (dB)
VOUT (V)
–2
10
fIF = 70MHz
Output Voltage and Slope Variation
vs RF Input Power and Temperature,
fIF = 70MHz
2.4
–4
TA = –40°C
0.4
TA = 25°C
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
TA = 25°C
0.4
SLOPE VARIATION (dB)
TA = –40°C
0
–2
0.8
SLOPE VARIATION (dB)
2
TA = 25°C
TA = 85°C
fRF = 1.9GHz
AVERAGE SLOPE: 23mV/dB
2.0
SLOPE VARIATION (dB)
1.6
0
1.2
6
2.4
4
2.0
2
TA = 25°C
Output Voltage and Slope Variation
vs RF Input Power and IF Frequency
VOUT (V)
2.4
4
TA = –40°C
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
10
6
fIF = 240MHz
AVERAGE SLOPE: 23mV/dB
1.6
–4
0.4
fRF = 2.5GHz
–6
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
2.0
2
TA = 25°C
0.8
–2
4
VOUT (V)
fRF = 900MHz
2.4
SLOPE VARIATION (dB)
2
6
SLOPE VARIATION (dB)
SLOPE VARIATION (dB)
fIF = 240MHz
AVERAGE SLOPE: 23mV/dB
Output Voltage and Slope Variation
vs RF Input Power and Temperature,
fRF = 2.5GHz
VOUT (V)
Output Slope Variation vs
RF Input Power and Frequency
6
(VCC = 3V unless otherwise noted).
VOUT
1V/DIV
PULSED
RF
900MHz
0dBm
1V/DIV
100ns/DIV
5504 G12
5504f
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LT5504
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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.
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.
RF– (Pin 3): Negative RF Input Pin.
LO (Pin 6): Local Oscillator Input Pin.
GND (Pin 4): Ground Pin.
VOUT (Pin 7): Output Pin.
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BLOCK DIAGRA
VCC
VCC
1
8
7
VOUT
+
DET
DET
LIMITING
MIXER
RF+
2
RF–
3
DET
DET
LPF
RF
LIMITER
IF
LIMITER
LO
BUFFER
•••
IF
LIMITER
ENABLE
6
4
5
LO
GND
EN
5504 BD
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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
50Ω broadband matching with an 82Ω 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.
5504f
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LT5504
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APPLICATIO S I FOR ATIO
2.5
fRF = 1.9GHz
2.0
VOUT (V)
WITH SINGLE-ENDED-TODIFFERENTIAL INPUT CIRCUIT
63.56Ω
–j98.05Ω
900.00MHz
2: 26.69Ω
–j42.90Ω
1.90GHz
3: 28.88Ω
–j27.76Ω
2.50GHz
1.5
1.0
WITH 1:1 INPUT TX
1:
0.5
3
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
1
2
0
10
5504 F03
STOP:3GHz
START: 100MHz
5504 F01
Figure 3. The Output Voltage vs RF Input Power
Figure 1. Differential RF Input Impedance
Limiting Mixer and LPF
MATCHING NETWORK
CS1
3.3pF
RF
INPUT
TO RF +
CS2
3.3pF
LSH
3.3nH
TO RF –
5504 F02
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
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
where RIN = 100Ω 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)
LSH(nH)
CS1/CS2(pF)
900
12.0
3.9
1900
3.3
3.3
2500
2.7
2.2
2700
2.4
1.5
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 400µA. An internal compensation capacitor
CC is used to guarantee stable operation for a large
capacitive output load. The slew rate is 80V/µs 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
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LT5504
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APPLICATIO S I FOR ATIO
to 400µA/CL. For example, the slew rate is reduced to 4V/
µs when CL = 100pF.
VCC
400µA
CC
+
VOUT
–
OUTPUT CURRENTS
FROM RF AND IF
DETECTORS
5504 F04
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.
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TYPICAL APPLICATIO S
C2
100pF
C1
RF
INPUT 100pF
C4
1nF
VCC
R3
10k
C3
1nF
1
R1
82Ω
T1
TOKO
617DB-1022
8
VCC
VCC
LT5504
2
7
RF +
VOUT
3
4
RF –
LO
GND
EN
JUMPER
R2
200Ω
VOUT
6
LO
INPUT
5
R5
500k
C7
100pF
R4
20k
5504 F04
Figure 5. LT5504 Evaluation Board Circuit Schematic
Figure 7. Component Side
Layout of Evaluation Board
Figure 6.Component Side Silkscreen of Evaluation Board
Figure 8.Bottom Side
Silkscreen of Evaluation Board
Figure 9. Bottom Side Layout
of Evaluation Board
5504f
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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LT5504
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PACKAGE DESCRIPTIO
MS8 Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660)
3.00 ± 0.102
(.118 ± .004)
(NOTE 3)
0.889 ± 0.127
(.035 ± .005)
5.23
(.206)
MIN
3.2 – 3.45
(.126 – .136)
0.254
(.010)
7 6 5
3.00 ± 0.102
(.118 ± .004)
NOTE 4
4.88 ± 0.1
(.192 ± .004)
DETAIL “A”
0.52
(.206)
REF
0° – 6° TYP
GAUGE PLANE
0.65
(.0256)
BSC
0.42 ± 0.04
(.0165 ± .0015)
TYP
8
1
0.53 ± 0.015
(.021 ± .006)
RECOMMENDED SOLDER PAD LAYOUT
DETAIL “A”
2 3
4
1.10
(.043)
MAX
0.86
(.34)
REF
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
SEATING
PLANE
0.22 – 0.38
(.009 – .015)
0.65
(.0256)
BCS
0.13 ± 0.05
(.005 ± .002)
MSOP (MS8) 1001
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300MHz to 7GHz Precision RF Power Detector
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5504f
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Linear Technology Corporation
LT/TP 0305 500 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2002