LT5504
800MHz to 2.7GHz
RF Measuring Receiver
FEATURES
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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
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RSSI Measurements
Receive AGC
Transmit Power Control
ASK and Envelope Demodulation
GSM/TDMA/CDMA/WCDMA
The LT
®
5504 is an 800MHz to 2700MHz monolithic inte-
grated 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 down-
converted IF signal obtained using the on-chip mixer and
an external local oscillator. The RF- and IF-detected sig-
nals 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
V
CC
V
OUT
OUTPUT
V
OUT
(V)
R2
200Ω
C3
10pF
RF
INPUT
R1
82Ω
RF+
RF
DETECTOR
IF
DETECTOR
•••
IF
DETECTOR
RF –
ENABLE
EN
GND
LO
5504 TA01a
LO
INPUT
U
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)
f
RF
= 900MHz
f
IF
= 240MHz
AVERAGE SLOPE:23mV/dB
6
4
SLOPE VARIATION (dB)
U
U
2
0
–2
–4
–6
10
0
5504 TA01b
5504f
1
LT5504
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
CC
RF
+
RF
–
GND
1
2
3
4
8
7
6
5
V
CC
V
OUT
LO
EN
Power Supply Voltage ............................................ 5.5V
V
OUT
, EN ................................................................ 0,V
CC
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
LT5504EMS8
MS8 PART MARKING
LTGP
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 160°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL
RF Input
f
RF
Frequency Range
Input Impedance
DC Voltage
LO Input
f
LO
Frequency Range
Input Return Loss
DC Voltage
P
LO
LO Power
LO to RF Leakage
PARAMETER
T
A
= 25°C. V
CC
= 3V, P
LO
= –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 50Ω
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
f
IF
Frequency
Linear Dynamic Range (Note 4)
Output Voltage
Output Voltage at f
RF
= 900MHz, f
LO
= 1140MHz
Average Slope
Output Voltage at f
RF
= 1900MHz, f
LO
= 2140MHz
Linear Dynamic Range (Note 4)
Output Voltage
Average Slope
2
U
5504f
W
U
U
W W
W
LT5504
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
Linear Dynamic Range (Note 4)
Output Voltage
Output Voltage at f
RF
= 2500MHz, f
LO
= 2260MHz
T
A
= 25°C. V
CC
= 3V, P
LO
= –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
µA
µV/√Hz
µV/√Hz
ns
ns
µs
kΩ
V
V
5.25
14.7
22
30
V
mA
µA
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
t
ON
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
V
CC
I
CC
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 • V
CC
0.4 • V
CC
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 –40°C to 85°C 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
f
IF
= 240MHz
2.0
SUPPLY CURRENT (mA)
18
16
14
T
A
= –40°C
12
T
A
= 85°C
20
1.6
V
OUT
(V)
f
RF
= 900MHz
1.2
0.8
0.4
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
f
RF
= 1.9GHz
f
RF
= 2.5GHz
U W
0
5504 G01
Supply Current vs Supply Voltage
and Temperature
Power Up Response Time
V
CC
= 3V
RF INPUT POWER = 0dBm
V
OUT
1V/DIV
T
A
= 25°C
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
2µs/DIV
5504 G03
5504f
3
LT5504
TYPICAL PERFOR A CE CHARACTERISTICS
Output Slope Variation vs
RF Input Power and Frequency
6
4
SLOPE VARIATION (dB)
2
0
f
RF
= 1.9GHz
–2
–4
50% VARIATION OR
SLOPE = 11.5mV/dB
f
RF
= 2.5GHz
–6
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
0
10
f
IF
= 240MHz
AVERAGE SLOPE: 23mV/dB
2.4
2.0
1.6
V
OUT
(V)
V
OUT
(V)
f
RF
= 900MHz
Output Voltage and Slope Variation
vs RF Input Power and Temperature,
f
IF
= 240MHz
2.4
2.0
1.6
f
RF
= 1.9GHz
AVERAGE SLOPE: 23mV/dB
6
4
2.4
2.0
V
OUT
(V)
1.2
0.8
0.4
T
A
= 25°C
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
0
T
A
= 85°C
T
A
= –40°C
0
–2
–4
–6
10
V
OUT
(V)
1.2
70MHz
400MHz
0.8
0.4
f
IF
= 400MHz
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
0
f
IF
= 240MHz
0
–2
–4
–6
10
V
OUT
(V)
T
A
= 25°C
T
A
= –40°C
Output Voltage and Slope Variation
vs RF Input Power and Temperature,
f
IF
= 70MHz
2.4
2.0
1.6
6
f
RF
= 1.9GHz
AVERAGE SLOPE: 23mV/dB
4
V
OUT
(V)
V
OUT
(V)
T
A
= 25°C
T
A
= –40°C
0
1.2
0.8
0.4
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
0
4
U W
5504 G04
(V
CC
= 3V unless otherwise noted).
Output Voltage and Slope Variation
vs RF Input Power and Temperature,
f
RF
= 2.5GHz
2.4
2.0
SLOPE VARIATION (dB)
Output Voltage and Slope Variation
vs RF Input Power and Temperature,
f
RF
= 900MHz
f
IF
= 240MHz
AVERAGE SLOPE: 23mV/dB
6
4
2
0
T
A
= 85°C
0.8
T
A
= 25°C
0.4
T
A
= –40°C
T
A
= –40°C
0
–2
10
0
–80 –70 –60 –50 –40 –30 –20 –10
PIN (dBm)
–4
–2
f
IF
= 240MHz
AVERAGE SLOPE: 23mV/dB
6
4
SLOPE VARIATION (dB)
T
A
= 25°C
1.6
T
A
= 25°C
1.2
T
A
= 85°C
0.8
T
A
= 25°C
0.4
T
A
= –40°C
T
A
= –40°C
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
f
RF
= 1.9GHz
AVERAGE SLOPE: 23mV/dB
f
IF
= 70MHz
4
Output Voltage and Slope Variation
vs RF Input Power and Supply Voltage
2.4
2.0
SLOPE VARIATION (dB)
1.6
V
CC
= 5.25V
1.2
0.8
0.4
V
CC
= 2.7V
V
CC
= 2.7V
0
–2
–4
–6
10
6
f
RF
= 1.9GHz
f
IF
= 240MHz
V
CC
= 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,
f
IF
= 400MHz
2.4
2.0
1.6
1.2
T
A
= 85°C
0.8
T
A
= 25°C
0.4
–4
T
A
= –40°C
0
–6
10
–2
f
RF
= 1.9GHz
AVERAGE SLOPE: 23mV/dB
6
4
SLOPE VARIATION (dB)
2
T
A
= –40°C
0
V
OUT
1V/DIV
Output Response Time
2
T
A
= 25°C
–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
5504f
LT5504
PI FU CTIO S
V
CC
(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 V
CC
/2. When the input voltage is higher than
0.6 • V
CC
, the circuit is completely turned on. When the
input voltage is less than 0.4 • V
CC
, the circuit is turned off.
LO (Pin 6):
Local Oscillator Input Pin.
V
OUT
(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 ampli-
fier, 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 on-
chip 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 volt-
age.
U
W
W
U U
U
U
U
V
CC
1
V
CC
8
7
V
OUT
+
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
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 cir-
cuit 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 adjust-
ment.
5504f
5
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