Class D amplifiers have become a popular audio amplifier topology due to their high efficiency and subsequent low cost. The high current output stage is implemented using binary switches, resulting in minimal heat generation and power loss. This allows for the power supply, heat sink and overall physical size of the amplifier to be minimized. Typical efficiency of a class D amplifier is over 90%, as opposed to 50% for a typical class AB amplifier. In an AB design, most of the inefficiency is a result of the output stage devices being required to operate in the linear region. As current flows though the devices, it is converted to heat instead of being delivered to the load.
This application note provides a method to implement a class D amplifier using only the analog features of the PIC24FV16KM202 and minimal external components. This leaves the processor completely available for other application processes. The design presented is a single channel, full bridge (push-pull) Class D amplifier.