An envelope tracking H-bridged audio amplifier with improved efficiency and thd less than 0.1%

In this paper, we present a class-H audio amplifier with an H-bridged output stage. System efficiency is improved by producing a voltage envelope that tracks the input audio signal. The tracking envelope is realized by regulating a buck converter internally using voltage and current hysteresis control schemes. The H-bridged class-B output stage is designed to maximize the output swing across the speaker load with little crossover distortion. The proposed design is capable of providing a peak output RMS power of 0.49 W to an 8 Ω speaker load. The entire system is designed and simulated in a 0.18-μm CMOS technology. In simulation, the proposed audio amplifier shows improved power efficiencies and good output linearities with THD less than 0.1% under different input signals.