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Design >> Analog Design >> Trouble to startup Colpitts Crystal Oscillator while easy with Pierce
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Message started by neoflash on Oct 20^th, 2009, 7:01pm

Title: Trouble to startup Colpitts Crystal Oscillator while easy with Pierce
Post by neoflash on Oct 20^th, 2009, 7:01pm

Hi Folks:

I'm coming up with a strange issue with Xtal oscillator. With Colpitts design, the Xtal is hard to compensate and the oscillation will not sustain.

However, the same X-tal model with similar transistor size and current, the pierce version can work pretty well.

I've attached both schematics on and hope you can help me analyze the problem.

Regards,
Neo

Title: Re: Trouble to startup Colpitts Crystal Oscillator while easy with Pierce
Post by neoflash on Oct 20^th, 2009, 7:02pm

Pierce version works well and easily start.

Title: Re: Trouble to startup Colpitts Crystal Oscillator while easy with Pierce
Post by neoflash on Oct 20^th, 2009, 7:51pm

I also tried to make Colpitts current / transistor size 10x larger. However, it still doesn't start up.