On 6/18/15 3:46 AM, Bob Camp wrote:
Hi
Be careful when you do find the data.
When you go very close in on something like a VCO, you get much higher phase
noise
than we normally worry about. Some of the “assumptions” that underly the
measurements
are no longer true. Small angle of modulation is one, but there are a few
others.
yeah that's a big one.. There's a slide in a recent Keysight/Agilent
presentation on phase noise measurement that has a line on it at, I
think, 30dB/decade going through -30dBc@1Hz or something as the
threshold where small angle approximation is no longer valid.
A simple
“plug it in and read it” may not give you valid information without some
corrections. Coming
up with a supply that’s good enough (at 1 Hz) would be a major challenge ...
Well, it's not like we're looking for 1E-10 ADEV in this sort of
application.
Mostly, it's a "what should you expect".. and also the whole "we all
know gunn oscillators are noisy, but how noisy, really"
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