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1-2 mA Ibias for OPA134 ... coal to Newcastle?

Posted by jcox on May 6, 2002 at 22:10:45:
using Ibias ~ .56 mA from Risch's 2nd reference thread ( see post below ) this whole discussion is probably irrelevant to OPA2134
OPAx134 data sheet gives open loop output impedance = 10 Ohm
from Zout = 1/2 * ( 26 mV / Ibias ) we can say output stage Ibias > 1.3 mA, unless they've used additional local feedback around the output stage transistors
also why FET constant current source? Bipolar source with vref diode or Wilson current sink can set Ibias to < 5% tolerance with no trimming required