Modelling and analysis of a high-performance Class D audio amplifier using unipolar pulse-width-modulation

A high-performance class D audio amplifier using unipolar pulse-width-modulation (PWM) with double-sided natural sampling is presented in this article. In order to comprehend and design the system properly, the class D audio amplifier is modelled and analysed. A wide range triangle-wave signal with good linearity and magnitude proportional to supply voltage is embedded in the proposed class D audio amplifier for maximum output power, high power supply rejection ratio (PSRR) and low total harmonic distortion (THD). Design results based on CSMC 0.5-µm 5-V complementary metal–oxide–semiconductor process demonstrate that the proposed class D audio amplifier can operate with supply voltage in the range 2.4–5.5 V and supports 2.8 W output power from a 5.5 V supply; the maximum efficiency is above 95%, the PSRR is −82 dB, the signal-to-noise ratio (SNR) is 97 dB and the total harmonic distortion plus noise (THD+N) is less than 0.1% between 20 and 20 kHz with output power 0.4 W; the quiescent current without load is 1.8 mA, and the shutdown current is 0.01 µA. The active area of the class-D audio power amplifier is 1.5 mm × 1.5 mm.

[1]  P. Mellor,et al.  Reduction of spectral distortion in class D amplifiers by an enhanced pulse width modulation sampling process , 1991 .

[2]  Luanne Seymour Cohen.  Design Essentials , 1995 .

[3]  Bah-Hwee Gwee,et al.  An investigation on the parameters affecting total harmonic distortion in class D amplifiers , 2000, 2000 IEEE International Symposium on Circuits and Systems. Emerging Technologies for the 21st Century. Proceedings (IEEE Cat No.00CH36353).

[4]  Marco Berkhout.  Integrated Class-D Amplifier , 2002 .

[5]  Wayne Chen,et al.  A filter free class D audio amplifier with 86% power efficiency , 2004, 2004 IEEE International Symposium on Circuits and Systems (IEEE Cat. No.04CH37512).

[6]  Simon S. Ang,et al.  A multi-loop voltage feedback filterless class-D switching audio amplifier using unipolar pulse-width-modulation , 2004, IEEE Transactions on Consumer Electronics.

[7]  M. Berkhout.  Integrated overcurrent protection system for class-D audio power amplifiers , 2005, IEEE Journal of Solid-State Circuits.

[8]  G. Burra,et al.  A 700+-mW class D design with direct battery hookup in a 90-nm process , 2005, IEEE Journal of Solid-State Circuits.

[9]  Enrico Dallago,et al.  A current-mode power sigma-delta modulator for audio applications , 2005, IEEE Transactions on Industrial Electronics.

[10]  Meng Tong Tan,et al.  An Analysis of THD in Class D Amplifiers , 2006, APCCAS 2006 - 2006 IEEE Asia Pacific Conference on Circuits and Systems.

[11]  Joseph Sylvester Chang,et al.  Modeling and analysis of PSRR in analog PWM class D amplifiers , 2006, 2006 IEEE International Symposium on Circuits and Systems.

[12]  Enrico Dallago,et al.  PWM Power Audio Amplifier With Voltage/Current Mixed Feedback for High-Efficiency Speakers , 2007, IEEE Transactions on Industrial Electronics.

[13]  R. Cellier,et al.  An integrated class D audio amplifier based on sliding mode control , 2008, 2008 IEEE International Conference on Integrated Circuit Design and Technology and Tutorial.

[14]  R. Cellier,et al.  A high performance switching audio amplifier using sliding mode control , 2008, 2008 Joint 6th International IEEE Northeast Workshop on Circuits and Systems and TAISA Conference.

[15]  Zhu Zhangming,et al.  A high efficiency PWM CMOS class-D audio power amplifier , 2009 .

[16]  Willy Sansen,et al.  analog design essentials , 2011 .