[time-nuts] OT: xtal osc PN

[Richard (Rick) Karlquist]

A couple of disclaimers here:

1.  Leeson's oscillator model was mentioned.  That
doesn't apply much to crystal oscillators.  The close
in noise will be limited by the intrinsic noise of
the crystal and the far out noise will be limited by
the buffer amplifier.  Leeson's model never comes
into play.  BTW, the intrinsic noise of the crystal
is higher than the thermal noise corresponding to
its ESR, at least below 1 kHz or so.

2.  Using crystal filters to clean up after the fact
is limited by the intrinsic noise of the crystals in
the filters.  Hence, this usually only makes sense
if you multiply a xtal oscillator then filter, as
in the HP8662, and then it only improves the noise
floor.

Unless you have access to very low noise crystals,
you are not going to get very far building your
own oscillator.

Rick Karlquist N6RK