A Review and Comparison of Pulse Width Modulation (PWM) Methods For Analog and Digital Input Switching Power Amplifiers

摘要

Switching power amplifiers can be based on numerous different and rather complicated non-linear modulation methods. This work is an attempt to review and compare a complete collection of 12 pulse width modulation methods, of which several have not been considered before. There is a lack of such fundamental reference material, and it is thought that further development in the field can result from a more fundamental and in-depth understanding of the principles involved. All major modulations classes: natural sampled PWM (NPWM), unifrom sampled PWM (UPWM) and hybrid sampling schemes are analyzed and compared by analytical means and by simulation. A new efficient analysis tool, the Harmonic Envelope Surface (HES) is introduced to aid in the deep understanding of the modulation processes. Detailed measurements for an implemented amplifier example are given, to illustrate the possibilities for high end audio specifications by high efficiency switching power amplification.