Design and realization of a randomized modulation scheme for digital class D amplifiers

• Main Author: Cheng, Kuan Teng.
• Other Authors: Chang Joseph Sylvester
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Applications of electronics
• Online Access: http://hdl.handle.net/10356/54456
• Institution: Nanyang Technological University

Digital Class D amplifiers are increasingly prevalent in portable audio electronic devices because of their high power-efficiency and simple hardware advantages. Digital Class D amplifiers typically modulate the output signal using the Pulse Width Modulation Scheme (PWM). The PWM, unfortunately, generates undesirable harmonics of the input signal that cause distortion in the output signal. A randomized modulation scheme denoted as the Randomized Wrapped-Around Pulse Position Modulation (RWAPPM) scheme has been earlier proposed to mitigate harmonic distortions in the output PWM signal of DC-to-DC converters. Due to the similar nature of (switched-mode) operation in both the DC-to-DC converter and Class D amplifier, it is proposed in this Final Year Project (FYP) to investigate and when feasible, adopt and realize the RWAPPM for mitigating the harmonic distortions in Class D amplifiers. This report describes the simulation and realization of the RWAPPM scheme for digital modulators of Class D amplifiers. To show that the RWAPPM is feasible for Class D amplifiers, the RWAPPM scheme is simulated in MATLAB. A digital modulator embodying the RWAPPM for Class D amplifiers is implemented using a hardware description language, and verified by means of computer simulations.