In a negative feedback opamp while performing KCL at the input node (to which feedback is attached), in which direction is the current flowing 'actually' through the feedback resistance..i mean in one way if you think about the input supply, current flows from input side to feedback(because of high i/p imp of opamp no current flows into opamp) but if we think of what a feedback does, it feels like current flows from output side to input side...i cant come to a conclusion.help please..

Question

kenljw · Answer

For correct bias of Op amp looking out from the - and + input should be same impedance, a biasing network should be added to + input so as to adjust for Op input Voltage and Current Offsets.  Now the principle of Virtual Ground can be used, the voltage at the - input equals the + input so not current enters into the Op amp and you can use KCL at the - input.

anonymous · Answer

well..actually i wanted to know in which direction does the current flow in the feedback resistance?

kenljw · Answer

Well you now know no current goes into Op Amp therefore the current through the feedback resistor must go into the input resistor.

anonymous · Answer

the current direction is always is taken from the input side to the o/p via feedback path since the i/p resistance of op-amp is infinite and no current enters in it.