Μw Path Control - Agilent Technologies X Series Manual

of the top line of the display and the values represented by the trace data. Thus, the values of exported
trace data, queried trace data, marker amplitudes, trace data used in calculations such as N dB points,
trace math, peak threshold, and so forth, are all affected by Ref Level Offset.
Changing the offset causes the analyzer to immediately stop the current sweep and
NOTE
prepare to begin a new sweep, but the data will not change until the trace data
updates, because the offset is applied to the data as it is taken. If a trace is exported
with a nonzero Ref Level Offset, the exported data will contain the trace data with
the offset applied.
The maximum reference level available is dependent on the reference level offset. That is, Ref Level -
Ref Level Offset must be in the range –170 to +30 dBm. For example, the reference level value range
can be initially set to values from –170 dBm to 30 dBm with no reference level offset. If the reference
level is first set to –20 dBm, then the reference level offset can be set to values of –150 to +50 dB.
If the reference level offset is first set to –30 dB, then the reference level can be set to values of –200
dBm to 0 dBm. In this case, the reference level is "clamped" at 0 dBm because the maximum limit of
+30 dBm is reached with a reference level setting of 0 dBm with an offset of –30 dB. If instead, the
reference level offset is first set to 30 dB, then the reference level can be set to values of –140 to +60
dBm.
µW Path Control
The functions include the
µW Path Control
Path (Option LNP) controls in the High Band path circuits.
When the µW Preselector is bypassed, the user has better flatness, but will be subject to spurs from out
of band interfering signals. When the Low Noise Path is enabled, the analyzer automatically switches
around certain circuitry in the high frequency bands which can contribute to noise, when it is appropriate
based on other analyzer settings.
For most applications, the preset state is Standard Path, which gives the best remote-control throughput,
minimizes acoustic noise from switching and minimizes the risk of wear-out in the hardware switches.
For applications that utilize the wideband IF paths, the preset state is the µW Preselector Bypass path, if
option MPB is present. This is because, when using a wideband IF such as the 140 MHz IF, the µW
Preselector's bandwidth can be narrower than the available IF bandwidth, causing degraded amplitude
flatness and phase linearity, so it is desirable to bypass the preselector in the default case.
Users may choose Low Noise Path Enable. It gives a lower noise floor, especially in the 21–26.5 GHz
region, though without improving many measures of dynamic range, and without giving the best
possible noise floor. The preamp, if purchased and used, gives better noise floor than does the Low Noise
Path, however its compression threshold and third-order intercept are much poorer than that of the
non-preamp Low Noise Path. There are some applications, typically for signals around 30 dBm, for
which the third-order dynamic range of the standard path is good enough, but the noise floor is not low
enough even with 0 dB input attenuation. When the third-order dynamic range of the preamp path is too
little and the noise floor of the standard path is too high, the Low Noise Path can provide the best
dynamic range.
Key Path
µW Preselector Bypass
AMPTD Y Scale
AMPTD Y Scale
(Option MPB) and
Low Noise
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