An 80% peak efficiency, 410mW, single supply rail powered Class-I linear audio amplifier

A Class-I audio amplifier with an integrated DC/DC converter implemented in 0.18-μm CMOS process is presented. Efficiency is improved by adopting a self-generated adaptive supply, which tracks the audio signal and keeps a small voltage across output transistors. The employed gain compression technique uses only one positive supply to maintain good linearity, and achieve above 20% better efficiency over a conventional Class-AB design. Without using negative supply, this Class-I amplifier is compatible with a standard CMOS process. Experimental results show that the peak efficiency is 80%. The THD+N is less than 0.06% when output power is less than 300mW for an 8Ω load.