High-Drive and Linear CMOS Class-AB Pseudo-Differential Amplifier

A CMOS pseudo-differential-input differential-output amplifier operating in class AB and exhibiting high-current-drive capability is presented. The circuit operates from a Minimum Supply of V-T + 2V(DS,SAT), provides fast settling response, and also characterized by a wide input differential range with high linearity that enables its use even as a transconductor for filtering applications. For this purpose, a common-mode feedback section is also included. A circuit prototype was fabricated using a 0.35-mu m technology and powered with 2 V. Using a quiescent current of 20 MA, experimental measurements show a differential current-drive capability of 1 mA (which is 50 times greater than the quiescent value), with this value being solely limited by the input voltage swing allowed. Third-order harmonic distortion is lower than -64 dB for a 1-Vpp 100-kHz input.