[sdiy] ota's as gates.

[Tim Parkhurst]

I want to see what the EEs have to say on this, but from what I've seen it's
generally a bad idea to feed a chip inputs that are outside of its supply
rails. 

What say the experts?

Tim (outside the rails) Servo
"Imagination is more important than knowledge." - Albert Einstein




> -----Original Message-----
> From: Nils Pipenbrinck [mailto:np at inverse-entertainment.de]
> Sent: Tuesday, February 03, 2004 12:33 PM
> To: Synth-Diy
> Subject: [sdiy] ota's as gates.
> 
> Dumb question maybe, but anyways.
> 
> I'm designing a little noise gate circuit around a 3080. I can't guarantee
> that my control-voltage will down to -V however. Right now I always have a
> little bit of current flowing into the Iabc input, and thus the OTA does
not
> shut down completely.
> 
> This lead me to the strange idea to just raise the negative supply of the
> OTA a bit.. maybe a diode drop or so. I think that way I get a little
> dead-zone.
> 
> Would this work? Will the ota misbehave if I try to pull the Iabc input
pin
> below the negative supply voltage?
> 
> Thanks,
> 
>   Nils



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