Abstract
Presented is a 0.9V rail-to-rail constant g m CMOS amplifier input stage consisting of complementary differential pairs and a g m control circuit. The g m control circuit eliminates the g m dead zone, which occurs in the conventional rail-to-rail amplifier with ultra-low supply voltages. The proposed amplifier input stage has a constant g m 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 0.35m standard CMOS technology. © 2009 The Institution of Engineering and Technology.