Keysight Technologies Option 503 Service Manual page 228

Analog/Digital IF Troubleshooting
A2 Analog IF Assembly Theory of Operation
Post Down Conversion Amplification and Prefiltering
In IQ Analyzer mode or in Spectrum Analyzer mode with Sweep Type of
FFT, the analyzer span setting determines the pre-filter settings.
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The 22.5 MHz IF goes through a fixed gain amplifier. Then prefilters are
switched in and out. The signal then goes through a variable gain amplifier.
The prefilters provide four single-pole filters to limit the bandwidth of the
signal reaching the ADC on the A3 Digital IF assembly. There are five
different signal paths for the 22.5 MHz IF when using Signal Analyzer swept
mode:
1. LC wide
2. LC narrow
3. Crystal wide
4. Crystal narrow
5. Through path
The LC wide signal path is used when the analyzer Res BW setting is
180 kHz to 390 kHz.
The LC narrow signal path is used when the analyzer Res BW setting is
30 kHz to 160 kHz.
The Crystal wide signal path is used when the analyzer Res BW setting is
4.3 kHz to 27 kHz.
The Crystal narrow signal path is used when the analyzer Res BW setting is
< 3.9 kHz.
The through path is used when the analyzer Res BW setting is 430 kHz and
greater in analyzer swept mode.
N9030A PXA Signal Analyzer Service Guide