Magnus Danielson wrote:
Also, modern cheap programmable TCXOs break the model as they have a hump in the phase noise due to their locked PLL, which the original model does not allow for. The autocorrelation function will be quite different. Notice how this ripples over to other locked oscillators such as passive masers, GPSDO etc.
Yes.. once one moves beyond a simple oscillator/resonator and amplifier, you're out of the zone where the simple Leeson model will work all the time. the curves have lumps and bumps, and simple approximations of integration don't work any more.
And then, you have the whole explaining "why do I care what the phase noise/Allan deviation is" or trying to relate noise performance to overall system performance. (e.g. what happens if the phase noise at 1MHz offset is 20 dB worse than expected?)
For some simple cases, blackboard sketches of reciprocal mixing and such help, but when it gets more complex... or when you're trying to relate an integrated phase jitter spec to the distribution that creates it....
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