This paper presents a new single-stage fully-differential class AB folded-cascode operational transconductance amplifier (OTA) for low-voltage and fast-settling switched-capacitor circuits in pure digital CMOS technology. The proposed OTA employs class AB operation in both the input-stage and output current source transistors resulting in large slew rate, enhanced unity-gain bandwidth and DC gain. The method to build the class AB operation in the output current source transistors is very simple which does not need any extra circuit and power consumption. HSPICE simulation results are presented to show the usefulness of the proposed OTA's structure.