[time-nuts] DMTD - analog multiplier vs. diode mixer ?

Bob Camp kb8tq at n1k.org
Sun Jan 10 14:12:56 UTC 2016


Hi


> On Jan 10, 2016, at 5:32 AM, Attila Kinali <attila at kinali.ch> wrote:
> 
> Moin phk!
> 
> On Sat, 09 Jan 2016 22:56:27 +0000
> "Poul-Henning Kamp" <phk at phk.freebsd.dk> wrote:
> 
>>> Single gate chips better than multi gate chips.
>>> (no interference through the power supply of the different sub-parts)
>> 
>> Would paralleing multiple gates in the same chip make things
>> better or worse ?
> 
> Good question. I have no idea.
> 
> My first guess would be, that it would only give a slight improvement,
> if at all.
> 
> The reasoning is the following:
> Under the assumption that the noise of all gates is ergodic and stationary,
> then averaging the outputs of the gates should reduce the output noise.
> 
> But the noise is not truly ergodic and there will be coupling between the
> gates (both through the power supply and the outputs), that will change the
> noise properties of the gates. Which in turn might lead to positive interference
> of the noise, instead of averaging out.
> 
> But I have to admit that noise in electronic circuits is for me still
> something very unintuitive. And I am more often wrong than right, when
> it comes to predicting noise behavior.

How do the gate outputs combine? 

Often the “pull down” part of the gate is stronger than the “pull up” part of the gate. 
If that’s what happens, you get an odd voting process rather than an average ….
( one gate says low, two gates say high, we go low ….)

Bob


> 
> 			Attila Kinali
> -- 
> It is upon moral qualities that a society is ultimately founded. All 
> the prosperity and technological sophistication in the world is of no 
> use without that foundation.
>                 -- Miss Matheson, The Diamond Age, Neil Stephenson
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