Q of the resonator
guy said that the Q of the resonator is not necessarily the higher the better. He
actually prefers a lower Q (range 2K~3K) instead of high Q (over 10K). Sounds
counter-intuitive to me. Anybody can help me figure out why?
Thanks.
It is possible that he is attempting to avoid over-voltage which could cause arcing to occur within the waveguide and damage it and other expensive components
Robert A. Patterson
http://quantumgravitics.tripod.com
Lower Q of the tank needs if the design is a VCO with wide frequency range.
The result of lower Q is:
-greater phase noise (reduced tank amplitude vs. transistor noise).
-greater sensitivity to tuning-line noise (which translates directly into frequency modulation).
-potential startup problems (especially at extreme temperatures).
-greater challenge in designing the loop filter.
Why don't you ask him? There could be a couple of reasons, or he could just be a crackpot.
A low Q will cause increasing phase noise and tank loss. So theoretically it should as large as possible.
if you don't care about phase noise oscillator and an exactly resonance frequency so you can use a low Q resonator
the q is higher
the s11 of the amp is need to be higher
the Q AUGMENT for lesslos
I agree with expect the phase noise.
Amplitude will be reduced with lower Q, but usually the phase noise will increase. and with lower amplitude, the S/N will be reduced.
So far, I try to select high Q resonator especially high Q inductor for greater phase noise.
Besides, lower Q means high current.
So if you don't care the current consummation, lower Q can be employed for wide frequency range design.
Its very simple..higher the Q, lower the phase noise. But sometimes bandwidth considerations limit the Q you want!