Keysight Technologies N5221A, Руководство по обслуживанию

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5-4 Keysight N5221A/22A 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 Table 5-3 . 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).
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) as the test signal. 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.
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/N5221-90002.pdf and
http://literature.cdn.keysight.com/litweb/pdf/N5221-90001.pdf
1
.
Refer to “Synthesized Source Group Operation” on page 5-6 .
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)
— optional step attenuators in the source and receiver paths
— optional bias tees
Refer to
“Signal Separation Group Operation” on page 5-16 .
Receiver Group
The receiver converts the test and reference signals to 7.438 MHz intermediate
frequency (IF) signals for signal processing, retaining both magnitude and
phase characteristics. The IF signals are converted to digital information by the
digital processing group.
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).