Re: Definition of Colpitts Oscillator

From: sjcma (ma_at_removethis.canada.com)
Date: 11/15/04 

Date: Mon, 15 Nov 2004 00:52:12 -0500

Rich Grise wrote:
> On Sat, 13 Nov 2004 21:23:13 -0500, sjcma wrote:
>
>
> As far as I know, there isn't. The way I learned it, the definition
> of a Colpitts is a parallel resonant circuit with a tapped capacitor,
> with signal ground at the junction of the caps, so the ends are 180
> degrees out of phase, so it's a natural feedback path. Or something
> like that. One end to the output and the other to the input, basically.
> And the Hartley is the same thing with the coil and caps swapped. ;-)
>
> The rest is window dressing. :-)
>

Hi Rich,

I've seen circuits like that described as being a Colpitts oscillator.
But I've also seen the exact same circuit being described as a Pierce
oscillator, where an inverting amplifier (could be a digital inverter)
is attached to a parallel-C, series L or crystal, and parallel-C before
feeding back to the input of the inverting amplifier.

So is it a Colpitts or Pierce? Or is the Pierce name strictly for xtal
oscillators?

Stan

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