DC1078A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1078
MEAN-S Q U AR ED R F P O W ER D ET EC T O R
LT5570
DESCRIPTION
Demonstration circuit 1078 (DC1078A) is a MeanSquared RF Power detector featuring the LT5570.
The LT5570 is a wide dynamic range RF detector, operational from 40MHz to 2700MHz. The input dynamic range at 2140MHz with ±1dB nonlinearity is
51dB (from –38dBm to +13dBm. The detector output
voltage slope is normally 37mV/dB, and the typical
output variation over temperature is ±0.3dB at
2140MHz.
NOTE: DC1078A demo circuit is optimized for input
frequency of 2140MHz +/- 150MHz. Refer to page 3
for modifications for 2700MHz and 880MHz.
Design files for this circuit board are available. Call
the LTC factory.
LTC is a trademark of Linear Technology Corporation
Table 1. Typical Performance Summary (VCC = 5V, ENBL = 5V, TA = 25°C, unless otherwise noted. Test circuit shown in Figure 2.)
PARAMETER
CONDITION
Supply Voltage
4.75V to 5.25V
Supply Current
Shutdown Current
VALUE
26.5mA
ENBL = Low
0.1µA
Low, Chip Disabled
1V max
HIGH, Chip Enabled
2V min
VENBL = 0V
0µA
VENBL = 5V
68µA
Output Start Voltage
No Input Signal Present
0.1V
Rise Time
0.2V to 1.6V, 10% to 90%, C1 = 22nF, FRF = 2140 MHz
0.5µs
Fall Time
1.6V to 0.2V, 90% to 10%, C1 = 22nF, FRF = 2140 MHz
8µs
ENBL Voltage
ENBL Input Current
Input Frequency Range
2140MHz to 2700MHz
f = 2140MHz
Linear Dynamic Range
±1 dB linearity error
51 dB
Slope
36.5mV/dB
Logarithmic Intercept
-42.4dBm
Output Variation vs Temperature
PIN = -50 to +13dBm
±0.3 dB
Deviation from CW Response
12 dB peak-to-average ratio (4 carrier WCDMA)
0.2 dB
±1 dB linearity error
48 dB
f = 2700MHz
Linear Dynamic Range
Slope
36.4mV/dB
Logarithmic Intercept
-38.5dBm
Output Variation vs Temperature
PIN = -50 to +13dBm
±0.2 dB
Deviation from CW Response
12 dB peak-to-average ratio (4 carrier WCDMA)
0.5 dB
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1078
MEAN-S Q U AR ED R F P O W ER D ET EC T O R
QUICK START PROCEDURE
Demonstration circuit 1078 is easy to set up to evaluate the performance of the LT5570. Refer to Figure 1
for proper measurement equipment setup and follow
the procedure below:
5.
Connect signal generator’s output to demo board
INPUT port (SMA connector J1) via coaxial cable.
A 3dB attenuator may be inserted to improve input
match.
1.
Connect voltmeter’s negative (-) lead to demo
board GND test point (TP2).
6.
2.
Connect voltmeter’s positive (+) lead to the demo
board OUTPUT test point (TP4).
Using a jumper cable, connect demo board VCC test
point (E3) to ENBL test point (TP3). Now the detector is enabled (on) and is ready for measurement.
3.
Connect DC power supply’s negative (-) output to
demo board GND test point (TP2).
4.
Connect DC power supply’s positive (+) output
(4.75V to 5.25V) to demo board VCC test point
(TP1).
NOTE: Do
not exceed 5.5V, the absolute maximum
supply voltage.
NOTE: Make sure that the power is not applied to
Enable (EN) test point before it is applied to VCC.
The voltage on the EN test point must never exceed VCC + 0.2V.
7.
Apply RF input signal and measure OUTPUT DC
voltages.
NOTE: Do not exceed +15dBm, the absolute maximum RF input power.
Figure 1. Proper Measurement Equipment Setup
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1078
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DEMO BOARD MODIFICATIONS:
Demo board modifications for RF input frequency of 2700MHz
Part
Notes
Value
Manufacturer Part Number
L1
Remove L1 inductor.
1.2pF
Murata, GRM1555C1H1R2CZ01
2.2nH
TOKO, LL1005-FHL2N2S
Place 1.2pF capacitor instead of inductor L1.
C7
Remove capacitor C7.
Place 2.2nH inductor instead of capacitor C7.
T1
Remove T1 balun (LDB212G1020C-001).
Murata, LDB212G4020C-001
Place LDB212G4020C-001 Murata balun instead.
NOTE: Refer to demo board schematic on Page 4
Demo board modifications for RF input frequency of 880MHz
Part
Notes
Value
Manufacturer Part Number
L1
Remove L1 inductor.
1.8nH
TOKO, LL1005-FHL1N8S
No placement
n/a
Place 1.8nH inductor instead.
C7
Remove capacitor C7.
T1
Remove T1 balun (LDB212G1020C-001).
Murata, LDB21869M20C-001
Place LDB21869M20C-001Murata balun instead.
NOTE: Refer to demo board schematic on Page 4
Note: Consult factory for demo board modifications for other frequencies.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1078
MEAN-S Q U AR ED R F P O W ER D ET EC T O R
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