An Ultra-Low-Voltage Ultra-Low-Power CMOS Miller OTA With Rail-to-Rail Input/Output Swing

An ultra-low-voltage ultra-low-power CMOS Miller operational transconductance amplifier (OTA) with rail-to-rail input/output swing is presented. The topology is based on combining bulk-driven differential pair and dc level shifters, with the transistors work in weak inversion. The improved Miller OTA has been successfully verified in a standard 0.35-mum CMOS process. Experimental results have confirmed that, at a minimum supply voltage of 600 mV, lower than the threshold voltage, the topology presents almost rail-to-rail input and output swings and consumes only 550 nW.