Microchip Technology GPS-2700, User Manual

Page: 28 / 77

GPS-2700 User’s Guide
DS50003016A-page 28
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2020 Microchip Technology Inc.
Beginning in August 2012 and with BOM revision 2.1, the GPS-2700 board had a com-
ponent change that improves the phase noise filter performance significantly, espe-
cially below 2
kHz offsets from the carrier. Please see Figure 2-17 for a typical plot of
the new phase noise performance of the unit. This change also reduces the jitter of the
10
MHz outputs considerably. The following plot shows operation with the phase noise
filter disabled (light trace) and enabled (darker trace). Noise performance improve-
ments by the filter of almost 20
dB can be seen at 1 kHz offsets over the CSAC oscil-
lator by itself.
FIGURE 2-17: Phase Noise of the GPS-2700 with the Phase Noise Filter
Enabled.
The plot in Figure 2-18 shows the GPS-2700 unit's Phase Noise performance as a plot
of two superimposed measurements, one with the Phase Noise filter enabled and one
with the filter disabled. The noise improvement and reduction of spurs is clearly visible.
Phase Noise performance is improved by up to 13
dB (at 10 kHz offset).
Figure 2-19 shows an alternate comparative phase noise plot.
FIGURE 2-18: Both Phase Plots Superimposed.