[time-nuts] Phase noise & Jitter

[Bruce Griffiths]

Hal Murray wrote:
>> For digital circuits, it would seem that the potential for
>> metastability & threshold uncertainty, is reduced when the
>> slope-to-noise ratio is optimized. I wonder if this concept is, or can
>> be quantified?
>>     
>
> I don't think noise hurts or helps metastability.  For every case where it 
> might hurt there is the mirror image where it helps.
>
>
> I would expect a slower rise time to cause more metastability.  Here is the 
> way I think about it.  If you have N ns to settle, there is a window in 
> voltage that is Y mV wide.  (give or take some statistics)  The signal with 
> the faster rise time will spend less time inside that window.
>
> There is probably some limit where making it faster doesn't help any more.
>
>
> Speaking of rise time...
>
> I'm somewhat looking for a signal generator - digital rather than sine wave.
>
> I'm pretty sure I used an HP box 10-20 years ago that had knobs on the rise 
> and fall times as well as frequency and whatever.  Is there some obvious unit 
> is should be looking for?  Do they show up on eBay?  ...
>
>
>
>   
Perhaps an HP8082A, but it all depends on what range of risetimes etc 
you need.

There's one currently listed on ebay.

Bruce