Hello, The transistor is NPN and are you applying possitive supply voltage to the emitter and negative to the colector?
Regards, Javier Jenny Lee escribió: > 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@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- ------------------------------------------------------------------------ Javier Herrero EMAIL: [EMAIL PROTECTED] HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17A FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
