Service Guide N5227-90001 5-13
PNA Series Microwave Network Analyzers Theory of Operation
N5227A Synthesized Source Group Operation
A4, A15, and A17 13.5 GHz Synthesizer Boards
The A17 13.5 GHz synthesizer board is included only on 4-port models.
The A4, A15, and A17 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 Ta b l e 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 11-35, 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
Ta b l e 5- 1 .
The output of the A15 13.5 GHz synthesizer board (the LO synthesizer) is 7.438 MHz higher than the output
of the A4 and A17 13.5 GHz synthesizer boards (the source synthesizers). This is because the output of the
A15 13.5 GHz synthesizer board is routed through the A25 LO multiplier/amplifier 26.5 board to the A27 and
A28 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 “A27 and A28 Mixer Bricks” on page 5-25 for a more complete
description.
A5 and A10 26.5 GHz Source Boards
In bands 2–9, the A5 and A10 26.5 GHz source boards input signals from the A4 or A17 13.5 GHz synthesizer
board are passed through to both outputs (main and secondary) unchanged.
For bands 10-15, 19-23, and 29-31, the input signals are passed directly to the secondary output or amplified
and filtered, then sent to the main output.
For bands 16-18, 24-28, and 32-35, 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.
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