A wideband low-offset current-feedback op amp design

Abstract

A current-feedback op amp design technique that reduces the offset voltage without degrading the bandwidth and the input dynamic range is described. The use of the basic push-pull buffer as the op amp input stage results in low inverting-input impedance, which improves the closed-loop gain-bandwidth product. The offset voltage is reduced by making the bias currents of the input buffer vary as a function of the mismatch between the n-p-n and p-n-p V/sub be/'s. The dynamic input range and open-loop gain are increased by the use of a modified Wilson current mirror.<>