27th International AES Conference
 

PAPER SESSION 3: MODULATION AND CONTROL



3-4 Derivation and Analysis of a Low-Cost, High- Performance Analog BPCM Control Scheme for Class D Audio Power Amplifiers


Mikkel C. W. H°yerby, Michael A. E. Andersen. Technical University of Denmark, Lyngby, Denmark


This paper presents a low-cost analog control scheme for class D audio power amplifiers. The scheme is based around bandpass current-mode (BPCM) control and provides ample stability margins and low distortion over a wide range of operating conditions. Implementation is very simple and does not require the use of operational amplifiers. Small-signal behavior of the controller is accurately predicted, and design is carried out using standard transfer function based linear control methodology. Effectiveness of the approach is demonstrated via a 60-W/8-W single-ended switching amplifier with THD+N of typically 0.02 percent.


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