5-6 Keysight N5227B Service Guide
Theory of Operation
Network Analyzer System Operation
5-
Synthesized Source Group
The built-in synthesized source generates a swept, stepped, or continuous
wave (CW) signal in the frequency ranges as listed in the
Data Sheet and
Technical Specifications documents
, available online at:
www.keysight.com
.
1
The source group provides five signals: an LO signal and four incident signals.
The LO signal and the four incident signals are offset in frequency by the
receiver IF of 7.438 MHz (at tuned frequencies below 53 MHz the IF and the
offset is 0.826 MHz).
LO Behavior without LFE (Low Frequency Extension):
The LO signal is sent directly to the mixers in the receiver group. The incident
signals are routed to the front panel test ports and then to the device under
test (DUT). A portion of each incident signal is coupled off (in the signal
separation group) and sent to the mixers in the receiver group as reference
signals. These reference signals are compared (mixed) with the LO signal in the
receiver group to produce the 7.438 MHz (or 0.826 MHz at frequencies below
53 MHz) IF signal.
LO Behavior with LFE (Low Frequency Extension):
On the synthesizer board, there is a LFE output that is limited by the C-R filter
and by the 250 MHz low pass filter.
Below 20 MHz, the LFE is signal is directly converted. Exceptions are shown in
. See also,
“A70 4-Port and A75 2-Port Low
Frequency Extension (LFE) Board” on page 5-20
The incident signal output power is leveled by an internal automatic leveling
control (ALC) circuit. The maximum output power level of the network analyzer
at the test ports can be found in the Data Sheet and Technical Specifications
documents, available online at:
http://literature.cdn.keysight.com/litweb/pdf/N5227-90005.pdf
and
http://literature.cdn.keysight.com/litweb/pdf/N5227-90006.pdf
Refer to
“Synthesized Source Group Operation” on page 5-8
Signal Separation Group
Each of the incident signals from the source group is separated into a reference
path and a test path. The reference signal is transmitted to the receiver group.
The test signal is transmitted through—and reflected from—the DUT and is then
transmitted to the receiver group.
The signal separation group includes:
— RF path switching to allow forward and reverse measurements
— external connections for the DUT (configurable test set)
1. For frequency ranges and maximum output power levels, refer to the section “Test
Port Output” in the
Data Sheet and Technical Specifications documents (see
hyperlinks above).
