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The article presents a new fully differential operational transconductance amplifier (OTA) for low-voltage and fast-settling switched-capacitor circuits in pure digital CMOS technology. Because of the class AB operation of the second stage, the currents in this stage are determined so that the non-dominant poles and zeros are sufficiently large in frequency to maintain stability. Thus, the second-stage currents are not constrained by the slew rate limiting of the OTA, which results in power saving in the switched-capacitor circuits. To move the mirror pole and zero to a high frequency, NMOS transistors are used in the active current mirrors.

A single-stage class AB multipath operational amplifier is presented. The proposed amplifier uses the previously idle devices in a folded-cascode amplifier in the signal path and a flipped-voltage follower cell to build the class AB operation. It results in enhanced unity-gain bandwidth and DC gain and large slew rate with the same power consumption as the folded-cascode amplifier. Circuit level analysis and simulation results are provided to verify the effectiveness of the proposed amplifier. [ABSTRACT FROM AUTHOR]

A correction to the article "Single-Stage Class AB Operational Amplifier for SC Circuits," that was published in the previous issue, is presented.