Low voltage low thd CMOS audio (power) amplifier

摘要

A low voltage low THD CMOS audio power amplifier (60) which can work at lower supply voltage with lower THD is presented. A Class AB input stage (40) is provided that can be used in the extremely low THD circuit (60). Compared to a conventional differential input stages (30), for a given quiescent current consumption, the Class AB input stage (40) achieves a much larger output dynamic current and a higher slew rate. In addition, the input stage (40) achieves a flat signal/distortion versus frequency characteristic. A Class AB output stage (80) has a higher over-drive gate-source voltages for the output transistors and thus has a higher driving capacity as compared to a conventional output stage (70) making it suitable for low voltage CMOS designs operable at supply voltages as low as 1.5 volts.