Re: Missing Schmitt Gates??

On Mon, 3 Dec 2007 17:57:28 -0800, "Joel Koltner"
<JKolstad71HatesSpam@xxxxxxxxx> wrote:

"D from BC" <myrealaddress@xxxxxxxxx> wrote in message
news:q9r8l355qlqetlub2mqgma5a281ho5a7n6@xxxxxxxxxx
Nonlinear elements like clipping, xover and nonlinear transfer in the
feedback path mess up the frequency stability.

Yes, although it's often not as bad as you'd first think.

I don't see how all these linear requirements can be achieved with
digital parts meant for digital applications.

Because the digital parts don't "know" that they were only meant for digital
applications. :-)

A crystal needs a good linear amp.

Everything is linear if you look closely enough...

I am being a little obtuse here -- the kind of oscillator I was thinking of
was your canoncial microcontroller/FPGA clock that doesn't need to be
particularly accurate -- it's common to use 50 or even 100ppm rocks in such
systems; this is a completely different league of oscillator than those you
build for, e.g., fancy RF applications where you're after 2.5ppm or better.


I was never able to get the Schmitts to oscillate anywhere near the
supposed crystal frequency.

John



---Joel


.

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