[time-nuts] DIY Low offset Phase Noise Analyzer (Erik Kaashoek)

[Mike Monett]

Eric,

Another problem I forgot to mention, the exclusive-or phase detector has a
severe output ripple. This will cause frequency shift in the oscillator
frequency which will show up in the measurements.

The phase-frequency detector has zero ripple at lock. There is a small
transient at the sample time, but this is easily filtered with a simple low
pass filter.

With zero ripple in the output, the PFD will not cause any shift in the
oscillator frequency. This will not cause any error in the measurements.