QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 748A
50MHZ TO 3GHZ RF POWER DETECTOR WITH 60dB DYNAMIC RANGE
LT5534
DESCRIPTION
Demonstration circuit 748A is a wide range RF power
detector featuring the LT
®
5534.
The LT5534 is a 50MHz to 3GHz monolithic RF power
detector capable of measuring RF signals over a 60dB
dynamic range. The RF signal in a decibel scale is
precisely converted into DC voltage on a linear scale.
The 60dB input dynamic range is achieved using cas-
caded RF detectors and RF limiters. Their outputs are
summed to generate an accurate log-linear DC volt-
age proportional to the input RF signal in dB. The
output is buffered with a low output impedance
driver. The LT5534 features superior temperature
stability and fast transient response (typical full-scale
setting time is 38ns).
Design files for this circuit board are available. Call
the LTC factory.
Table 1. Typical Performance Summary (V
CC
= 3V, EN = 3V, T
A
= 25°C, source impedance = 50Ω
,
unless otherwise noted. Test
Ω
circuit shown in Figure 1.)
PARAMETER
Supply Voltage
Supply Current
Input Impedance
Output Impedance
Output DC voltage
f
RF
= 50MHz
RF Input Power Range
Dynamic Range
Output Slope
Output Variation vs. Temperature
f
RF
= 900MHz
RF Input Power Range
Dynamic Range
Output Slope
Output Variation vs. Temperature
f
RF
= 1900MHz
RF Input Power Range
Dynamic Range
Output Slope
Output Variation vs. Temperature
Output intercept
f
RF
= 2500MHz
RF Input Power Range
Dynamic Range
Output Slope
Output Variation vs. Temperature
P
in
= -48dBm to -14dBm, T
A
= -40°C to 85°C
±3dB Linearity Error, T
A
= -40°C to 85°C
-63dBm to -3dBm
60dB
35mV/dB
0.025dB/°C
P
in
= -48dBm to -14dBm, T
A
= -40°C to 85°C
50Ω External Termination, T
A
= -40°C to 85°C
±3dB Linearity Error, T
A
= -40°C to 85°C
-63dBm to -2dBm
61dB
36.6mV/dB
0.012dB/°C
-64dBm
P
in
= -48dBm to -14dBm, T
A
= -40°C to 85°C
±3dB Linearity Error, T
A
= -40°C to 85°C
-60dBm to 0dBm
60dB
41mV/dB
0.008dB/°C
P
in
= -48dBm to -14dBm, T
A
= -40°C to 85°C
±3dB Linearity Error, T
A
= -40°C to 85°C
-58dBm to +2dBm
60dB
44mV/dB
0.007dB/°C
No RF Input Signal
CONDITION
VALUE
2.7V to 5.25V
7mA
2kΩ
32Ω
142mV
1
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 748A
50MHZ TO 3GHZ RF POWER DETECTOR WITH 60dB DYNAMIC RANGE
QUICK START PROCEDURE
Demonstration circuit 748A is easy to set up to evalu-
ate the performance of the LT5534. Refer to Figure 1
for proper measurement equipment setup and follow
the procedure below:
NOTE:
Demonstration
5.
6.
Connect RF signal generator output to demo board
RF in port (SMA connector J1) via coaxial cable.
Using a jumper cable, connect demo board Vcc pin
(E1) to EN pin (E4). Now the detector is enabled
(on) and is ready for measurement.
NOTE:
Make
circuit 748A is optimized for
evaluations over the frequency range from 50MHz to
2.5GHz. Its RF input port is well matched with better
than 10dB return loss up to 2.5GHz. At higher fre-
quencies, return loss can be improved with proper
matching.
Connect DC power supply negative (-) output to
demo board Gnd pin (E3 or E5).
Connect DC power supply positive (+) output (2.7V
to 5.25V) to demo board Vcc pin (E1).
NOTE:
Do
7.
sure that the power is not applied to the
EN pin before it is applied to the Vcc pin. The volt-
age on the EN pin must never exceed the voltage
on the Vcc pin.
1.
2.
Apply an RF input signal and measure Vout DC
voltage.
not exceed +10dBm, the absolute maxi-
mum RF input power.
NOTE:
Do
not exceed 5.5V, the absolute maximum
supply voltage.
8.
3.
4.
Connect voltmeter negative (-) lead to demo board
Gnd pin (E3 or E5).
Connect voltmeter positive (+) lead to the demo
board Vout pin (E2).
The dynamic range is defined as the range over
which the linearity error is within ±3dB. The linear-
ity error is calculated by the difference between the
incremental slope of the output and the average
output slope from -48dBm to -14dBm.
Figure 1. Proper Measurement Equipment Setup
2
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