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Colpitts oscillator PSPICE
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[QUOTE="darkbasic, post: 4981403, member: 539033"] Finally I found the problem(s), there were many of them! 1) The biggest one were the initial conditions. After selecting "Skip the initial transient bias point calculation" (SKIPBP) in PSpice simulation's options everything got better. 2) Another big problem was in the math: I didn't size reactances well. I did it well, but just barely. In fact assuming A*B(jw0)=1 you barely get a persistent oscillation and a small rounding is enough to let it fade. So I assumed A*B(jw0)=100 when sizing reactances. 3) I had to put another small resistor in the project (R2=1f) because otherwise the simulation didn't converge, but it seems it was too small and I still had convergence problems in some circumstances. So I changed it to 1 mOhm instead. 4) The output capacitor took a long time to load (which wasn't a problem), but also lead to convergence problems in some circumstances. So I changed it to 1nF. 5) I also increased the current generator I1 to 1mA to get the oscillations sooner. 6) Finally I sized the reactances once again, assuming L=C1*10^3 to get more realistic values (but it works even if they are balanced). 7) Now THD is ~1% for the first 50 harmonics! [ATTACH=full]77933[/ATTACH] [ATTACH=full]77933[/ATTACH] [ATTACH=full]77934[/ATTACH] [ATTACH=full]77935[/ATTACH] [ATTACH=full]77936[/ATTACH] [ATTACH=full]77937[/ATTACH] [ATTACH=full]77938[/ATTACH] Thanks for your help Svein, it is much apreciated! [/QUOTE]
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Colpitts oscillator PSPICE
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