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Design >> Analog Design >> 32kHz oscillator design
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Message started by ic_engr on Feb 5^th, 2013, 6:40pm

Title: 32kHz oscillator design
Post by ic_engr on Feb 5^th, 2013, 6:40pm

Folks

i am in the midst of finalizing a topology for xtal oscillator design. The choice I have is either pierce oscillator or differential relaxation oscillaotor with on-chip capacitor.

Apparantly I am having conflicting opinions regards to relaxatin oscillator consuming less current than the pierce.

Any suggestions ?

ic_engr

Title: Re: 32kHz oscillator design
Post by loose-electron on Feb 8^th, 2013, 6:43pm

how accurate do you need the 32KHz for a real time clock?

RC oscillators are not accurate.

Title: Re: 32kHz oscillator design
Post by Lex on Feb 11^th, 2013, 1:41am

Free running RC oscillator (I guess you mean relaxation oscillators) is not accurate indeed. What about one that is injection-locked?

Title: Re: 32kHz oscillator design
Post by ic_engr on Feb 11^th, 2013, 5:48am

Sorry,

I may have been misunderstood. I am referring to two topologies for crystal oscillator. Not RC vs. Pierce.

Using the crystal at 32kHz, which topoloogy is advantageous for power consumption and start-up time:

1. Pierce oscillator with crystal
2. Differential Relaxation oscillator with onchip C it has cross coupled NMOS with current sources and the crystal is connected across it.

ic_engr