An integrated low-voltage class AB CMOS OTA

We present a new circuit topology for a low-voltage class AB amplifier, The circuit shows superior current efficiency in the use of the supply current to charge and discharge the output load, It uses negative feedback rather than component matching to optimize current efficiency and performance, res ulting in a current boost ratio exactly equal to one. Measurement results f or an example circuit fabricated in a 2-mu m CMOS process are given, The ci rcuit uses a quiescent supply current of 0.2 mu A and is able to settle to a 1% error in 1.1 ms for a 0.4-V input step and a load capacitance of 35 pF . The circuit design is straightforward and modular, and the core circuit c an be used to replace the differential pair of other op-amp topologies.