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
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.