[time-nuts] yet another GPSDO design, or so

Attila Kinali attila at kinali.ch
Tue Jun 29 09:31:34 EDT 2010


On Tue, 29 Jun 2010 21:32:10 +1200
Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:

> Its possible to build a 24 bit resolution D/A using a synchronously 
> filtered PWM circuit.
> A pair of PWM outputs and a few relatively low precision resistors and 
> capacitors together with a low noise low drift reference are required.
> The technique takes advantage of the fact that the required EFC voltage 
> changes slowly and isnt updated at a highg rate.
> The synchronous filter technique eliminates the very long time constant 
> RC filters required with an asynchronously filtered PWM waveform.

I've thought about that, but i'm afraid that this will add too
much phase noise trough EFC noise. Though, i have not calculated
how much noise this would generate.

			Attila Kinali
-- 
If you want to walk fast, walk alone.
If you want to walk far, walk together.
		-- African proverb




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