322 Keysight N9038A MXE Service Guide
Analog & Digital IF
A2 Analog I.F. Assembly Description
A2 Analog I.F. Assembly Description
A2 Analog IF Assembly Purpose
The instrument’s RF input signal is down converted to a 322.5 MHz
intermediate frequency in the A13 RF Front End Assembly. This 322.5 MHz
signal is the input to the A2 Analog I.F. Assembly. The Analog I.F. down
converts the 322.5 MHz signal to a final 22.5 MHz intermediate frequency. In
order to obtain optimal dynamic range and minimize unwanted spurious
signals, this signal is filtered, amplified and attenuated throughout this
assembly. The final 22.5 MHz signal goes through a series of variable band
pass filters each having a specific bandwidth. Three things determine the
signal path and which filters are chosen:
— Instrument resolution bandwidth (RBW) setting
—Application used
—Mode applied
This assembly also contains the burst carrier trigger circuitry. The output of the
assembly is a filtered 22.5 MHz signal that goes to the A3 Digital I.F. Assembly.
A2 Analog IF Assembly Description
A 322.5 MHz input signal is received from the A13 RF Front End assembly. The
signal then goes through a band pass filter centered at 322.5 MHz with a
25 MHz bandwidth. A cal comb signal can be automatically switched in at the
input of the assembly to calibrate the prefilters.
Step Attenuator and Amplifier
A 1 dB step attenuator follows to compensate for band gain differences.
The signal then goes through a high-dynamic range amplifier.
Image Filters
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.
Refer to Chapter 15, “Block Diagrams”.
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