[sdiy] Opamp as a comparator

[Happy Harry]

Having just completed a quantizer design that needed
a comparator (hysteresis was not possible) and having a
TL072 not be fast enough... and the LM311 is an ill-behaved
beast without hysteresis...

I used the CA3080.  Slew can be up to 80V/us...set by the
Iabc.  Worked very well, try it ;^P

H^) harry


>From: John Speth <JohnS at molectron.com>
>To: "'synth-diy at dropmix.xs4all.nl'" <synth-diy at dropmix.xs4all.nl>
>Subject: [sdiy] Opamp as a comparator
>Date: Wed, 6 Mar 2002 09:34:06 -0800
>
>Hi list-
>
>I'm working on a quantizer project that uses a comparator.   I started the
>design using an LM311 hoping to exploit the OC output for driving 5V logic.
>I quickly found out that a 0-5V output swing results in an asymmetrical
>hysteresis.  Now it's a plain old +/-15V comparator with positive feedback
>for hysteresis.  I might as well have used an opamp as a comparator to save
>the trouble of a pull up at the output.
>
>My questions are: Are suitably fast opamps just as effective as purpose
>built comparators in comparator applications?  How do I determine if an
>opamp is fast enough for my application?
>
>John Speth
>mailto:johns at molectron.com




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