PSN-L Email List Message

Subject: Re: Op-Amps
From: John Popelish jpopelish@........
Date: Thu, 10 Mar 2005 19:39:45 -0500

Douglas Gavilanes wrote:

> You might try the OP80A, which is very low noise and has a high input
> impedance.  A decent second could be the LF356, unless you're locked
> into another package.  Just a thought.  Of course, the OP80 is out of
> production now, I believe, but if you can find some, let me know!
> Seriously...

Not only can't I find a source for the OP80A, I can't locate a data
sheet.  If you have a PDF datasheet file, you are welcome to email it
to me.

I will include the LF356 in the survey, because it is well suited for
second and later filter stages where high value input resistors (low
bias current and low current noise) may be involved and its fairly
large offset voltage is not so important.  It really needs nearly a
full +-15 volt supply to produce a perfect +-10 volt output, though. 
There are others that do as well with a +-12 volt supply.  

I hope to produce a graphical comparison of many types that are
optimum choices for various source impedances, at around 1 hertz
(lower than the frequency considered in many comparison charts I have
seen).  That 1/f corner frequency where the noise starts to rise as
frequency falls makes all the difference. 

Looks like I may have to build a web page.

John Popelish

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