5-16 Keysight N5227B Service Guide
Theory of Operation
Synthesized Source Group Operation
5-
A56, A57, A58, and A59 70 GHz Doubler Boards
The 70 GHz doubler boards create the full output frequency range of 10 MHz
to 70 GHz by combining two input signals from the 40 GHz doubler boards.
The first input signals are from the 40 GHz doubler P2 output (bands 39 - 48),
where the signals are filtered, doubled, amplified, and sent to the combiner.
The second input signals are from the 40 GHz doubler P6 output (bands 2 -
38), where the signals are passed through the 70 GHz doubler and sent to the
combiner. The forward combiner then combines both signals to create a full
range of 10 MHz to 70 GHz output.
A25 Multiplier/Amplifier 26.5 Board (HMA26.5)
In bands 2–15 and 23-26, the synthesized LO input is filtered, amplified, and
passed through to the A26 splitter (4-port only). In bands 16-22 and 27-35 ,
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.
Rear-Panel Interconnects
10 MHz REF INPUT
A BNC connector that allows an external frequency reference signal to be used to
phase lock the analyzer for increased frequency accuracy.
The analyzer automatically enables the external frequency reference feature when
a signal is connected to this input. When the signal is removed, the analyzer
automatically switches back to its internal frequency reference.
10 MHz REF OUTPUT
A BNC connector that allows a 10 MHz reference signal, produced by the A14
frequency reference board, to be output for use in phase locking external test
equipment.
