Class-D Amplifier Power Stage With PWM Feedback Loop

This paper presents a second-order pulsewidth modulation (PWM) feedback loop to improve power supply rejection (PSR) of any open-loop PWM class-D amplifiers (CDAs). PSR of the audio amplifier has always been a key parameter in mobile phone applications. In contrast to class-AB amplifiers, the poor PSR performance has always been the major drawback for CDAs with a half-bridge connected power stage. The proposed PWM feedback loop is fabricated using GLOBALFOUNDRIES' 0.18-μm CMOS process technology. The measured PSR is more than 80 dB and the measured total harmonic distortion is less than 0.04% with a 1-kHz input sinusoidal test tone.

[1]  Ralph Mason,et al.  A low power Class D audio amplifier with discrete time loop filter compensation , 2009, 2009 Joint IEEE North-East Workshop on Circuits and Systems and TAISA Conference.

[2]  Stephen M. Cox,et al.  Class-D Audio Amplifiers with Negative Feedback , 2005, SIAM J. Appl. Math..

[3]  Bah-Hwee Gwee,et al.  An investigation into the parameters affecting total harmonic distortion in low-voltage low-power Class-D amplifiers , 2003 .

[4]  Chun Kit Lam,et al.  A Class D amplifier output stage with low THD and high PSRR , 2009, 2009 IEEE International Symposium on Circuits and Systems.

[5]  Hui Feng,et al.  A method of error correction for digital class D power amplifier , 2009, 2009 Asia Pacific Conference on Postgraduate Research in Microelectronics & Electronics (PrimeAsia).

[6]  Ranjit Gharpurey,et al.  Design and Analysis of a Self-Oscillating Class D Audio Amplifier Employing a Hysteretic Comparator , 2011, IEEE Journal of Solid-State Circuits.

[7]  V.F. Pires,et al.  Narrow Pulse Elimination PWM for Multilevel Digital Audio Power Amplifiers Using Two Cascaded H-Bridges as a Nine-Level Converter , 2007, IEEE Transactions on Power Electronics.

[8]  Remy Cellier,et al.  Analysis and design of an analog control loop for digital input class D amplifiers , 2011, 2011 18th IEEE International Conference on Electronics, Circuits, and Systems.

[9]  Lars Risbo,et al.  Performance of an All-Digital Power Amplification System , 1998 .

[10]  B. Putzeys,et al.  Digital audio's final frontier , 2003 .

[11]  P. Midya,et al.  Digital correction of PWM switching amplifiers , 2004, IEEE Power Electronics Letters.

[12]  M.A.E. Andersen,et al.  Carrier Distortion in Hysteretic Self-Oscillating Class-D Audio Power Amplifiers: Analysis and Optimization , 2009, IEEE Transactions on Power Electronics.

[13]  Philip T. Krein,et al.  High-fidelity PWM inverter for digital audio amplification: Spectral analysis, real-time DSP implementation, and results , 2003 .

[14]  Claus Neesgaard,et al.  PWM Amplifier Control Loops with Minimum Aliasing Distortion , 2006 .

[15]  Chun Kit Lam,et al.  AC-Boosting Frequency Compensation with Double Pole-Zero Cancellation for Multistage Amplifiers , 2010, Circuits Syst. Signal Process..

[16]  Marco Berkhout,et al.  Class-D Audio Amplifiers in Mobile Applications , 2010, IEEE Transactions on Circuits and Systems I: Regular Papers.

[17]  Remy Cellier,et al.  A 0.01%THD, 70dB PSRR Single Ended Class D using variable hysteresis control for headphone amplifiers , 2009, 2009 IEEE International Symposium on Circuits and Systems.

[18]  J. van den Homberg,et al.  PowerDAC: a single-chip audio DAC with a 70%-efficient power stage in 0.5 /spl mu/m CMOS , 1999, 1999 IEEE International Solid-State Circuits Conference. Digest of Technical Papers. ISSCC. First Edition (Cat. No.99CH36278).

[19]  Karsten Nielsen.  PEDEC-a novel pulse referenced control method for high quality digital PWM switching power amplification , 1998, PESC 98 Record. 29th Annual IEEE Power Electronics Specialists Conference (Cat. No.98CH36196).

[20]  Karsten Nielsen,et al.  MECC-A Novel Control Method for High End Switching Audio Power Amplification , 1998 .

[21]  Chun Kit Lam,et al.  A second-order PWM-in/PWM-out class-D audio amplifier , 2013 .

[22]  Meng Tong Tan,et al.  Time-Domain Analysis of Intermodulation Distortion of Closed-Loop Class-D Amplifiers , 2012, IEEE Transactions on Power Electronics.

[23]  A. Yoneya,et al.  Low distortion digital pulse width modulation for audio class-D amplifier , 2004, IEEE International Symposium on Communications and Information Technology, 2004. ISCIT 2004..

[24]  Lars Risbo.  Discrete-time Modeling of Continuous-time Pulse Width Modulator Loops , 2005 .

[25]  S. Logan,et al.  Linearization of class D output stages for high-performance audio power amplifiers , 1994 .

[26]  Phil Mellor,et al.  Digital sampling process for audio class D, pulse width modulated power amplifiers , 1992 .