With the current maturity of Class-D audio amplifier architectures, amplifier fidelity and efficiency limitations are primarily at the device level. Silicon MOSFETs have been evolving for almost forty years, and their progress towards a perfect switch has slowed dramatically. There are some fundamental characteristics of MOSFETs that degrade sound quality and efficiency. In 2010, the enhancement mode Gallium nitride (GaN) power FET was introduced by Efficient Power Conversion (EPC), providing a large step towards the perfect switch.
Audio Engineering Society
May 11, 2017