Design of an efficient low voltage class-D audio power amplifier

Abstract

The high efficiency of Class-D audio power amplifier allows for longer talk time and produces much lesser heat than standard linear amplifiers. Therefore, Class-D audio power amplifiers are mainly applied in portable electronic devices such as hearing aids, headphone amplifiers, wireless phones, mp3 players and notebook computers where the high efficiency performance is essential to extend the battery life time. In this final year project, the author proposes a design of an efficient low voltage Class-D audio power amplifier which operates at 2.7~3.3V and -20~85oC. Using pulse width modulation (PWM) technique, the author successfully designed and implemented a half-bridge analog Class-D amplifier incorporated with second order integrator design. This PWM Class-D amplifier includes error amplifier, comparator, triangular waveform generator, gate driver, output stage, and low pass filter. By properly shaping the frequency response of the second order integrator, this project had achieved a staggering 90.6% power efficiency with only 0.0337% total harmonic distortion.