The input currents of a non-ideal op-amp are not exactly zero. They are close to zero though. My book (Sedra/Smith) says, typical input bias current values for general-purpose op amps that use bipolar transistors are [itex] I_B= 100nA [/itex]Swapnil said:Hi, I was wondering why is it that the input current for an ideal op-amp is always zero? They say that it is because of infinite impedence but where exactly is this impedence? Across the op-amp?