Rohde & Schwarz R&S SMU200A, Service Manual

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R&S SMU200A Test Procedures
1007.9845.82 1.43
E-12
I/Q modulation
Input Impedance (VSWR)
Test equipment
See section "
Test Assembly for Output Impedance (VSWR)"
, page 1.5 .
Test setup
Connect the test port to the I or Q input instead of the RF output.
Measurement Settings on DUT:
Frequency 900 MHz
Level 0 dBm
I/Q Settings menu:
Source Analog Wideband I/Q Input
State On
Settings on signal generator:
- Level 10 dBm
- Carrier frequency 1 to 50 MHz in 10 steps
Screw the VSWR bridge off and measure the level as reference level.
Connect the VSWR bridge to the I input and measure the level again.
The voltage ratio of test level to reference level is the output
reflection coefficient r of the DUT.
From this, the voltage standing wave ratio (VSWR) can be calculated
as follows:
VSWR = (1+r)/(1-r)
Repeat the measurement for the Q input.
RF level with I/Q modulation
Test equipment - Power meter (Table 1-2, item 8)
-
DC voltage source (Table 1-1, item 12)
Test setup
Connect the power meter to the RF output socket.
Connect the DC voltage source to the I or Q input.
Measurement Settings on DUT:
RF On
Frequency 900 MHz
Level 0 dBm
Measure the level without modulation as reference level.
I/Q Settings menu:
Source Analog Wideband I/Q Input
State On
Set the DC voltage source to 0.500 V and measure the level again.
The level difference is the required measurement value.