[sdiy] Newbie questions about summing buffers
ijfritz at comcast.net
Fri Feb 24 20:14:25 CET 2012
>Capacitor across Rf forms a low pass filter, helps dampen any high
>frequency oscillations at the output.
People often write this but it isn't quite true. The feedback cap
stabilizes the circuit by compensating for opamp nonidealities, not by
acting as a LP filter. IOW you can't clculate the cap size just from the
frequency of the spurious oscillations. There is a good TI writeup about
this online somewhere.
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