[time-nuts] Programmable clock for BFO use....noise

Attila Kinali attila at kinali.ch
Sun Sep 16 17:11:41 EDT 2018


On Sun, 16 Sep 2018 22:08:19 +0200
Gerhard Hoffmann <dk4xp at arcor.de> wrote:

> I'm also not a fan of using slowish, slew-rate challenged  logic as a 
> replacement
> for a low pass. When I want a low pass, I make it from nice, 
> time-invariant RLC.

Unfortunately, using a low pass after the divider will not
prevent the down-mixing. The down-mixing happens as an inherent
property of digital circuits. Any filtering you do afterwards
will be too late. If you want to have low noise, then the only
way is to produce a non-square wave signal. Or in other words:
use a divider built from harmonic mixers*.

			Attila Kinali

* That is, if you don't like Λ-dividers or DDS
-- 
<JaberWorky>	The bad part of Zurich is where the degenerates
                throw DARK chocolate at you.



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