An improved operational transconductance amplifier (OTA) is presented in this work.\nThe fully differential OTA adopts the current recycling technique and complementary NMOS and\nPMOS input branches to enhance the total transconductance. Moreover, in order to achieve higher\ncurrent efficiency, a data-driven biasing circuit was developed to dynamically adjust the power\nconsumption of the amplifier. Two comparators were added to detect the voltage difference at the\ninput nodes, and when the differential input is large enough to activate either comparator, extra\nbiasing current is activated and poured into the amplifier to enhance its slew rate and gain-bandwidth\nproduct (GBW). The threshold voltage of the complementary recycling folded cascode (CRFC)-based\ncomparator is configured to suppress overshoot. Complementary common-mode feedback (CMFB)\ntopology with local CMFB structure is built to acquire high common-mode gain. The OTA was\nfabricated in SMIC 0.18-microm CMOS technology. The experimental result based on a capacitive\nfeedback loop shows that the data-driven operation improves the average slew rate of the amplifier\nfrom 10.2 V/micros to 55.5 V/micros while the power only increases by 150%. The OTA has good potential to\nsatisfy the fast settling demands for capacitive sensing circuits.
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