Low-voltage, rail-to-rail, Gm-enhanced pseudo-differential class-AB OTA

This paper presents a new class-AB pseudo-differential operational transconductance amplifier (OTA) for low-voltage and high-speed switched-capacitor circuits. The proposed OTA employs partial positive feedback to enhance the input transconductance, thus increasing the open-loop DC gain and the unity-gain frequency. A push-pull configuration is used to obtain rail-to-rail output voltage swing. Using a 0.35-μm digital CMOS process, the proposed OTA can obtain 78-dB DC gain, 72.5° phase margin, 100-V/μs slew rate with 1-pF load capacitor, while draining 170-μA quiescent supply current from a single 1-V power supply voltage.