A two-stage rail-to-rail current mirror OTA for ultra-low-power applications

ABSTRACTIn this letter, an ultra-low-power, ultra-low-voltage operational transconductance amplifier (OTA) with full rail-to-rail input/output swing is presented. The proposed two-stage OTA is based on the bulk-driven current mirror (CM) amplifier topology with Gm-C frequency compensation technique. In addition, a transconductance boosting technique is used to enhance performance of the CM input stage structure. Simulation results in 0.18-μm metal-oxide semiconductor technology show the proposed OTA achieves a 85.8-dB DC gain and a gain bandwidth of 21.9 kHz while driving a 15-pF load. The amplifier consumes 292 nW @ 0.5 V, which makes it suitable for low-power applications.