120nm CMOS operational amplifier with pseudo-cascodes and positive feedback

Abstract

A fully differential 3-stage operational amplifier in 0.12/spl mu/m digital CMOS technology achieving a differential gain in excess of 86dB is presented. This operational amplifier contains only regular-VTh transistors. It uses a pseudo-cascode input differential stage and a pseudo-cascoded load for the high gain. Positive feedback is primarily implemented for a good common-mode rejection. A transit frequency of 46 MHz and a phase margin of 66/spl deg/ at a /spl plusmn/0.6V supply and with a load of 10pF have been measured. The current consumption is less than 1.7mA in the temperature range from -40 to +80/spl deg/C.