A4, A13, And A11 13.5 Ghz Synthesizer Boards; A5 And A8 26.5 Ghz Source Boards - Keysight N5221A Service Manual

PNA Series Microwave Network Analyzers Theory of Operation
N5221A/22A Synthesized Source Group Operation

A4, A13, and A11 13.5 GHz Synthesizer Boards

The A13 13.5 GHz synthesizer board is included only on 4-port models.
The A4, A11, and A13 13.5 GHz synthesizer boards use the 50 MHz reference signal from the A14 frequency
reference board to tune a VCO circuit that sweeps from 2 GHz to 4 GHz.
Refer to Table 5-1 and Figure 5-3 for band numbers and frequencies discussed here.
In bands 2-10, the output of the swept VCO is passed directly or through a divide-by-2, 4, or 8 circuit to
produce the output frequencies as listed in Table 5-1.
In band 6, the output of the swept VCO is passed through a divide-by-4 circuit and then sent to a Direct
Digital Synthesizer to produce the output frequencies for bands 2-4 as listed in Table 5-1.
In bands 11-21, the swept VCO signal is passed through a doubler circuit where the signal for some bands
are sent directly to the output of the synthesizer board while other bands are passed through another
doubler circuit then to the output of the synthesizer board to produce the output frequencies listed in
Table 5-1.
The output of the A11 13.5 GHz synthesizer board (the LO synthesizer) is 7.438 MHz higher than the output
of the A4 and A13 13.5 GHz synthesizer boards (the source synthesizers). This is because the output of the
A11 13.5 GHz synthesizer board is routed through the A21 LO multiplier/amplifier 26.5 board to the A23 and
A24 mixer bricks where they are mixed with the test signals to produce a 7.438 MHz IF signal for each of
eight receivers (A D and R1 R4). Refer to "A23 and A24 Mixer Bricks" on page 5-20 for a more complete
– –
description.

A5 and A8 26.5 GHz Source Boards

In bands 2–9, the input signals from the A4 or A13 13.5 GHz synthesizer board are passed through to both
outputs (main and secondary) unchanged.
For bands 10-15, the input signals are passed directly to the secondary output or amplified and filtered, then
sent to the main output.
For bands 16-21, the input signals are doubled, filtered, and amplified. The signals for these bands are then
either passed directly to the secondary output or passed through more amplification and filtering and sent to
the main output.
Together these signals for bands 2–21 create the full synthesized source output frequency range of 10 MHz
to 26.5 GHz. These output frequencies for each band are listed in Table 5-1.
The A5 26.5 GHz source board provides an EXT TSET DRIVE RF OUT signal to the rear panel. This signal is
output at a frequency range of 3.2–26.5 GHz for use with an external test set. This output is terminated with
a 50-ohm load on the A8 26.5 GHz source.
The companion signal, EXT TEST SET DRIVE LO, is output from the A23 mixer brick. Refer to "A23 and A24
Mixer Bricks" on page 5-20.
Service Guide N5222-90001 5-9