Oscillator buffer

[o pere o]

On 11/19/2012 04:14 PM, John Larkin wrote:

The mmic has something over 180 degrees of phase lag, and the two Ls
can be sized to make up the rest of 360. If the gain element's net
phase shift is zero, the thing will oscillate at the unloaded resonant
peak frequency of the resonator, which should give high Q. I think.
Anyhow, it works. It seems to do gated/burst oscillators pretty well
with ceramic coaxial resonators.

Ok. But to take profit from the resonator Q you have to be careful with
the loading. And you will have trouble finding inductors that achieve
the required high reactance (for instance, in your example, 5 uH at 100
MHz is not easy). With capacitors you don't have this problem.

And, at higher frequencies, you can just add some transmission line
length to tweak the phase.

Pere