0.9 V rail-to-rail constant gm CMOS amplifier input stage

Abstract

Presented is a 0.9 V rail-to-rail constant gm CMOS amplifier input stage consisting of complementary differential pairs and a gm control circuit. The gm control circuit eliminates the gm dead zone, which occurs in the conventional rail-to-rail amplifier with ultra-low supply voltages. The proposed amplifier input stage has a constant gm that varies by ±2.3% for rail-to-rail input common-mode levels. To verify the proposed amplifier design, an experimental prototype operational amplifier is also implemented using 0.35 µm standard CMOS technology.