[sdiy] fanning grounds vs. dirty/clean ground

René Schmitz uzs159 at uni-bonn.de
Tue Aug 20 20:25:58 CEST 2002


At 17:08 20.08.02 +0200, Theo wrote:
>It seems in general Opamps don't like capacitors on their outputs.
>On a resent project using a single supply voltage I had to put 100R on the
>output of the opamp buffering the reference voltage to prevent oscillation.
>I might miss something here, but it seems to me the same problem could
>happen with a opamp buffered "ground".

Right, that can happen. Opamps have a region of capacitance which they don't
like. Because the output stage forms another pole which leads to oscillations. 
(I.e. missing phase margin.) But then in this arrangement, I would place the 
decoupling caps from pos to neg rail and not to GND...

Cheers,
 René


-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159

 




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