A7, A8, A12, And A13 50 Ghz Doubler Boards; A25 Multiplier/Amplifier 26.5 Board (Hma26.5); A14 Frequency Reference Board - Keysight N5224A Service Manual

Theory of Operation
Synthesized Source Group Operation

A7, A8, A12, and A13 50 GHz Doubler Boards

The A12 and A13 50 GHz doubler boards are included only on 4-port models.
Refer to Table 5-1 and Figure 5-3
For bands 2–15, the lowband input ports of the A7, A8, A12, and A13 50 GHz doubler boards receive their
signals from the A5 and A10 source module OUT 1 and OUT 2 outputs. These signals are passed through to
the doubler board output unchanged.
For bands 16–30, the highband input ports of the A7 and A12 50 GHz doubler boards receive their signals
from the A5 and A10 source module P4 outputs. These signals are amplified by the A7 and A12 doubler
boards and output via the highband output ports to the highband input ports on the A8 and A13 doubler
boards.
For bands 16–18, the input signals of all four doubler boards are amplified and filtered, then sent to the
doubler board output.
For bands 19–30, the input signals of all four doubler boards are doubled, amplified and filtered, then sent to
the doubler board output.
Doubler board output signals for bands 2–30 create the full synthesized source output frequency range of 10
MHz to 50 GHz.
The A7 50 GHz doubler board provides an EXT TSET DRIVE RF1 OUT signal to the rear panel. This signal is
output at a frequency range of 3.2–19 GHz for use with an external test set. This output is terminated with a
50-ohm load on the A8, A12, and A13 doubler boards.
The companion signal, EXT TEST SET DRIVE LO, is output from the A27 mixer brick. Refer to
Mixer Bricks" on page 5-21.

A25 Multiplier/Amplifier 26.5 Board (HMA26.5)

Refer to Table 5-1 and Figure 5-3
In bands 2–15 and 23-25, the synthesized LO input is filtered, amplified, and passed through to the A26
splitter (4-port only). In bands 16–22 and 26-30, the input is amplified, doubled, and filtered, then sent to the
output.
Together, these signal paths create the full output frequency range of 10 MHz to 26.5 GHz that is sent to the
A26 splitter (4-port only) where the signal is divided and sent to the A27 and A28 (4-port only) mixer bricks
as the LO signal.

A14 Frequency Reference Board

This assembly provides stable reference frequencies to the rest of the instrument. A high stability 10 MHz
oven-controlled crystal oscillator (OCXO) normally provides the frequency standard. However, if a 10 MHz
external reference signal is detected at the 10 MHz EXT REF IN port on the rear panel, it is used as the
frequency reference instead.
The 10 MHz reference signal is used to phase lock a 100 MHz VCO. The output of this VCO is then divided by
ten to produce the 10 MHz EXT REF OUT rear panel signal and also a 10 MHz reference signal for the A16
signal processing ADC module (SPAM) board. The VCO output is also divided by two to produce 50 MHz
reference signals for the A4, A15, and A17 13.5 GHz synthesizer boards.
5-12
for band numbers and frequencies discussed here.
for band numbers and frequencies discussed here.
PNA Series Microwave Network Analyzers
N5224A and N5225A
"A27 and A28
Service Guide N5225-90001