OTA gm tolerance?

Haible_Juergen#Tel2743 HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de
Wed Jan 29 23:40:00 CET 1997


A stupid question:
Why do the specs of a 3080 ota show such a high
gm tolerance? Shouldn't the gm simply be the
S = d Ic / d Ube of the differential pair, and thus only
be a function of temperature and emitter current,
but not of component tolerances ?? Ok, there are
also some current mirrors, but if *these* would
have such a large error, there would be enormous
offset problems in the whole ota as well. So is
it really just the S of the pair which can vary over
100% ?? Can't believe it.
Any ideas ?

JH.



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