[time-nuts] Xtal-like Colpitts Oscillator

[Jenny Lee]

Oh, I'm applying negative 10V to it -- drawn opposite... > Date: Mon, 31 Mar 2008 17:40:51 -0400> From: cfharris at erols.com> To: time-nuts at febo.com> Subject: Re: [time-nuts] Xtal-like Colpitts Oscillator> > The first problem that jumps immediately to my eye is> your power supply is backwards.> > -Chuck Harris> > Jenny Lee wrote:> > Hi Everyone, I was hoping to get some words of wisdom on my oscillator that only oscillates in simulation! I have a> > MEMS device that resonates around 34 MHz at a given bias with Q of 100. I fit the impedance into a six-element> > equivalent model (similar to 4-element equivalent model of Quartz) and placed in a Colpitts configuration for the> > simulation. In the open-loop gain/phase plot, the peak barely passes 0 dB no matter what C1 and C2 I chose. For> > transient simulation, it does oscillates, but on a PCB, the circuit won't oscillate! I'm including the device> > impedance, circuit schematics and simulation results as an attachment. I've managed to oscillate 20 MHz device which> > has a higher maximum impedance than 34 MHz devices both in simulation and on a PCB - but for this I followed the> > guidelines of Colpitts for Quartz ranging at 10~20MHz. But above 20 MHz, for Quartz, overtones seem to be the way to> > go due to the manufacturing so I couldn't find any reference or circuits that operates Quartz for 30 MHz~50MHz ranges> > at a fundamental mode. I can only use fundamental mode for my device... I would really appreciate if you could share> > some of your experiences with Colpitts or any suggestions of what I can try to make it work... Thank you!-Jenny > > _________________________________________________________________ In a rush? Get real-time answers with Windows Live> > Messenger. http://www.windowslive.com/messenger/overview.html?ocid=TXT_TAGLM_WL_Refresh_realtime_042008> > > > > > ------------------------------------------------------------------------> > > > _______________________________________________ time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.> > _______________________________________________> time-nuts mailing list -- time-nuts at febo.com> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> and follow the instructions there.
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