User`s guide

Table Of Contents
362 Agilent E5505A User’s Guide
16
Reference Graphs and Tables
Approximate System Noise Floor vs. R Port Signal Level
The sensitivity of the phase noise measurement system can be improved by
increasing the signal power at the R input port (Signal Input) of the phase
detector in the test set. Figure 288 illustrates the approximate noise floor of
the N5500A test set for a range of R input port signal levels from –15 dBm to
+15 dBm. These estimates of sensitivity assume the signal level at the L port is
appropriate for either the microwave or the RF mixer that is used (+7 dBm or
+15 dBm, respectively). The approximate phase detector calibration constant
that results from the input signal level at the R port is shown on the right side
of the graph.
Figure 288 Noise floor for R input port
-140 -160 -170 -180-150
Approximate phase noise floor (dBc/Hz)
f 10kHz
R Port signal level (dBm)
Detector constant
Kφ (V/rad)
-15
+15
-5
+5
.02
.035
.6
.06
.11
.2
.35
E5505a_phase_det_sensitivity
27 Feb 04 rev 1