An input bias cancellation stage for an audio operational amplifier is
provided. The input bias cancellation stage includes an input
differential pair, a current mirror, and a bias duplicator transistor
that substantially duplicates the input bias current. The bias duplicator
transistor receives substantially the same emitter current as the
transistors in the input differential pair, and has substantially the
same Vce as the transistors in the input differential pair. The current
mirror mirrors the duplicated bias current and subtracts it from the
bases of the transistors in the input differential pair so that the input
bias current is substantially cancelled.