Transcription of Update Notes for Introduction to Radio Frequency …
1 Update Notes for Introduction to RadioFrequency DesignOctober 31, 2001,returned to web on Nov 9, got an e-mail the other day (that is, in 2001) that pointed out an error inChapter 7dealing with to do with Figure whichshows the effect of emitter bias current in an NPN Colpitts oscillator on startinggain and circuit used for analysis is presented here:In anideal NPN, the signal current presented to the emitter emerges from collector voltage is then generated, defined by the net impedancepresented to the is where I made an my analysis backin the pre PC era, I assumed that the impedance was resonant and is not a good assumption as you can show through a more really have to do the analysis with more resonance isaltered by the loading from the emitter current, astransformed through theColpitts network of C1 and next figures show a more up-to -date analysis in general character of the curve is unchanged, but the values are , the phase goes through zero degrees at a bias current of about the analysis by performing Frequency sweeps is.
2 Our assumptions were wrong with the first is easilydone with PSPICE or similar thanks to John Broderick from RF Integration Inc. in Lowell, MA, thesharp eyedreader who caught the error.
