Rohde & Schwarz SMU200A - Page 47

Test Procedures R&S SMU200A
1007.9845.82 1.20
E-12
Residual AM
Test assembly
See section "
Test Assembly for Residual AM”, page 1.3.
Test method The signal is AM-demodulated with a zero Bias Schottky Detector.
Measurement
 Settings on DUT
:
- Fr
equency 1 GHz
- Level according to the mixer specification in linear range
- AM-Source = internal
- AM Depth = 1%
- Lf-Gen-Frequency = 10 kHz
- Level = 8 dBm
 Setting on R&S FSQ analyzer:
- Coupling = DC, an external Preamplifier with > 30dB Gain and
a DC-blocking Capacitor is necessary (f
-3dB
< 10Hz)!
- FILTER-TYPE = FFT
- RBW = 100Hz
-
HzF
start
9900=
- HzF
stop
10100=
- DETECTOR = MAX PEAK
 Calibrate the setup:
Measure power level
ref
P [dBm] at f = 10 kHz.
 Sw
itch of AM.
Settings of the R&S FSQ analyzer:
- RBW = 3Hz
-
HzF
start
20=
- kHzF
stop
1=
- DETECTOR = SAMPLE
 Read Trace
(
)
µ T with
[
]
N,1 µ and 625
=
N from FSQ
Analyzer. Calculate the summed power:
(
)

=

=
N
startstop
T
N
FF
RBW
P
1
10/
10
µ
µ
 Repeat Measurement with
- R
BW = 100Hz
-
kHzF
start
1=
- kHzF
stop
23=
calculate Power as above
 Calculate the residual AM
:
[%]
10
2
1
10/
231120
ref
P
kHzkHzkHzHz
residual
PP
AM

+
=
Test frequencies
100 MHz, 500 MHz, 1 GHz, 2.0 GHz, 3 GHz, 4.0 GHz, 6 GHz.