Frequency compensation in two-stage operational amplifiers for achieving high 3-dB bandwidth

Abstract

A frequency compensation technique for achieving high 3-dB bandwidth in two-stage operational amplifiers is demonstrated in this paper. Due to the phenomenon of pole splitting in Miller's Compensation technique in classical op-amp, the 3-dB bandwidth reduces drastically. The technique demonstrated in this paper is a modification of Miller's Compensation technique to achieve a significant improvement in the 3-dB bandwidth by introducing an extra stage, consisting of MOS transistors (MOST). The coupling capacitor and a PMOS transistor operating in triode region is connected between the output of the extra stage and the input of the second stage. The simulations were carried out in Cadence VIRTUOSO environment using 0.18 μm CMOS process technology.