A2 Analog If Assembly Theory Of Operation - Keysight Technologies X Series Service Manual

Analog/Digital IF Troubleshooting
40 MHz BW IF Section

A2 Analog IF Assembly Theory of Operation

Refer to
Input Switch and Filter
Step Attenuator and Amplifier
Image Filters
Mixer
3rd LO
IF Comb Cal
Keysight N9010A EXA Service Guide
Chapter 12, "Block
A 322.5 MHz input signal is received from the A15 Front End Control
Assembly. The signal then goes through a band pass filter centered at
322.5 MHz with a 25 MHz bandwidth. A comb cal signal can be
automatically switched in at the input of the assembly to calibrate the
prefilters.
A 1 dB step attenuator follows to compensate for band gain differences.
The signal then goes through a high-dynamic range amplifier.
One of three different filter paths will be selected automatically, depending
on the analyzer mode.
•The through path is selected in IQ Analyzer Mode and wide-band
demod.
•The 12 MHz ceramic bandpass filter is used for normal Signal Analyzer
swept and FFT operation.
•The 300 kHz Surface Acoustic Wave (SAW) is used for ACP modes.
There are two mixers that reside on this assembly. The first mixer is used to
down convert the 322.5 MHz input to the final 22.5 MHz IF. The other mixer
is described in the IF Comb Cal section.
The 300 MHz 3rd LO signal comes from the A16 Reference Assembly and
conditions it for use as an LO in the two mixers that reside on this assembly.
The third LO power is ~ +10 dBm to optimize the conversion efficiency of the
first mixer.
The 2nd mixer is used to mix the 300 MHz LO from the Reference Assembly
with the 22.5 MHz cal comb signal from the A3 Digital IF to allow
calibration of the prefilters and overall passband phase and amplitude. The
signal is attenuated by 20 dB if necessary.
Diagrams.".
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