[sdiy] fost precision comparator ?

[jhaible at debitel.net]

You're a genious!
That's the sulution. Turning the disadvantage of a slow
input signal into an advantage ...
The Extra amplifier may even be driven into saturation,
as long as it has time enough to recover before the
zero crossing occurs.

Thank you,

JH.


> Hi Jürgen,
> 
> A tandem out of a precision amplifier and a more modest comparator 
> perhaps? Say a linear preamp with a gain of 10 or so, to make the slope 
> that the comparator sees steeper, and the requirements on the comparator 
> are relaxed by the gain of the preamp. It should be easier to meet these 
> drift specs with an opamp or maybe even a discrete amp .
> 
> Cheers,
>   René
> 
> jhaible at debitel.net wrote:
> > Hi
> > 
> > I'm looking for a comparator for a certain application
> > (zero crossing detection; not synth-related), where 
> > I need high speed and good precision.
> > 
> > Requirements are < 200uV drift (offset, hysteresis)
> > and < 30ns jitter
> > 
> > I want to detect the zero crossing of a slow (10kHz)
> > signal with constant (1V) amplitude. Propagation
> > delay may be longer than 30ns (it probably will be
> > longer because of the flat slope / low overdrive),
> > and offset may also be higher than 200uV, but
> > the *drift* (over 1/2 hour at fairly constant tempertature)
> > must be < 200uV, and the *jitter* from one zero crossing
> > detection to the next must be <30ns.
> > 
> > Open collector output required, or an output stage
> > that can be supplied with 3V ... 5V.
> > Analogue part can be supplied with +/-12V dual supply
> > or +5V single supply.
> > Must haqndle 0 ... 5V input range without damage,
> > +1V ... +4V (operating) common mode voltage.
> > 
> > Does anybody make comparators like this?
> > Maxim and Analog Devices, don't (just talked
> > to their application engineers).
> > Anybody else making 200uV / 30ns comparators ?
> > 
> > JH.
> > 
> > -------------------------------------------------
> > debitel.net Webmail
> > 
> 
> -- 
> uzs159 at uni-bonn.de
> http://www.uni-bonn.de/~uzs159
> 
> 
> 
> 
> 




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