Transistor impedance tolerance for Trimless VCO ? - RF Cafe Forums
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Post subject: Transistor impedance tolerance for Trimless VCO ? Posted: Wed Nov 09, 2005 6:32 am
I would like to do away with the trimmers on an existing VCO design (circa 250 MHz). The analysis thus far suggests this could work (basic tolerance analysis on passive parts, Varactor and PCB parasitic tolerance) BUT I have yet to determine the affect on tuning due to transistor tolerance. Can anyone suggest how I might approach this ?
The transistor in question is NE85630.
Thanks in advance
Post subject: OscillatorPosted: Wed Nov 09, 2005 7:23 pm
Unfortunately, the sensitivity to transistor characteristics of an oscillator is highly circuit-dependent. You'll need to tell us what kind of circuit you have. Some versions of SPICE have the ability to do Monte Carlo simulation with tolerances - that may help.
Post subject: Transistor impedance tolerance for Trimless VCO ?Posted: Thu Nov 10, 2005 12:25 pm
The oscillator circuit is a bog standard common emitter colpitt's.