Design of Filterless Class D Audio Amplifier
Date Issued
2007
Date
2007
Author(s)
Tsai, Chun-Hao
DOI
zh-TW
Abstract
Over the years, the commercial audio amplifiers are dominated by Class AB amplifier. However, most of Class AB amplifier power efficiency is below 70%, which reduces the overall system battery lifetime and increases the heat dissipation. Therefore, the Class D amplifier with the advantages of high efficiency has been widely investigated recently comparing to the Class AB amplifier.
A Class-D amplifier with conventional PWM modulation requires an output filter which needs large area and increasing cost. Therefore, we use unipolar switching pulse width modulation scheme to realize a filterless Class-D power amplifier. In this thesis, we focus on the implementation of Class D amplifier on a monolithic integrated circuit. We observed that the total harmonic distortion (THD) increases due to non-linearity in the triangular wave. To overcome this problem, negative feedback is applied to reduce the harmonic distortion.
The circuit is designed using TSMC (2P4M) 0.35um 3.3V CMOS process. The entire circuit contains an error amplifier, two hysteresis comparators, a triangular wave generator, gate-driver circuits, and the H-bridge. The details of the entire circuit will be described thoroughly in this thesis. When a 0.4V, 1KHz input sine wave is applied, the maximum THD is 0.13% and the efficiency is 88.5%.
Subjects
D類放大器
脈波寬度調變
音訊放大器
Class-D Amplifier
PWM
Audio Amplifier
Type
thesis