Class D Amplifier Prototype

The amplifier we use for the TV is getting old, and an annoying 50 Hz hum is finding its way to the speakers. So, of course, I decided to make my own amplifier. I’ve done that before, with a class B design, and this time I wanted to do something different.

The Class D Simple Amp

This amplifier is a Class D design, which means that it transforms the audio signal into a high-speed (200 kHz) digital signal. It then amplifies that digital signal; because of the digital nature, the amplifier MOSFETs will be either fully on or fully off. Since either no current is flowing (100% off) or the MOSFET has practically no resistance (100% on), there is very little heat produced, making the design energy-efficient.

Circuit diagram of the Class D Simple Amp

This is just a prototype that outputs mono audio. It’s there for me to learn about its behaviour (it’s different on a PCB compared to the earlier breadboard prototype I made) before I copy-paste the components to the final 2.1 (stereo + subwoofer) version.

Above you see the circuit diagram. I’ve shared the design under the GPL license, including the PCB layout, on Open Source Hardware Lab.

dr. Sybren A. Stüvel
dr. Sybren A. Stüvel
Open Source software developer, photographer, drummer, and electronics tinkerer