A practical modelling for the design of a sigma delta class D power switching amplifier and its pedagogical application

The class D amplifier is now well known in audio applications. Its excellent power ratio (greater than 90%) is the most important advantage. The MOS transistors switching power stage is able to drive a useful power up to 100W to the loud speaker. However, designing such an amplifier is more difficult than designing a classical class A or AB power amplifier. As a global and simple analysis is rarely found in the scientific literature, a simple method is presented here based on a simplified modelling, to design a sigma delta class D power switching amplifier as easily as possible. The experimental results are given to illustrate the design method. Finally, we explain how we exported this work towards pedagogical application and practical lessons for our engineer students.