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Design >> Mixed-Signal Design >> question about tuning range algorithm
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Message started by James Bond on Jan 10^th, 2008, 1:12pm

Title: question about tuning range algorithm
Post by James Bond on Jan 10^th, 2008, 1:12pm

Hi, all,

Can anybody recommend some materials about tuning range algorithm in crystal oscillator or programming crystal oscillator? Thank you very much.

james

Title: Re: question about tuning range algorithm
Post by Visjnoe on Jan 17^th, 2008, 5:38am

Dear James,

I have never implemented a tuning range algorithm for a crystal oscillator, but I would just like to mention that this might not be feasible
if phase noise is of importance. Typically, you will use a bank of binary scaled capacitors with MOS switches in series. The Q factor of these elements can never match the intrinsic Q of your crystal.

If phase noise is of no importance, I would use a binary scaled capacitor bank in combination with a binary search algorithm. The crystal oscillator clock drives a counter which counts for a fixed amount of time T. Every time T, you compare the count value with a wanted value.

Kind Regards

Peter