A 20-W stereo class-D audio output power stage in 0.6-μm BCDMOS technology

This paper presents a highly power efficient 2×20-W class-D audio output power stage implemented in 0.6-μm BCDMOS technology. The presented power stage is capable of driving 2×8-Ω loads from a 20-V power supply at a power efficiency approaching 90%. Circuit details of thermal detection, over-current protection, and startup speaker click/pop are also presented. The performance of open-loop Class-D output stages are limited by the distortion mechanisms present within the power stage itself. A third-order PWM modulator was prototyped and used to dramatically improve the performance of the Class-D output stage by using feedback. The results of this work are also presented.