Comparison of 60V GaN and Si Devices for Class D Audio Applications

Posted on: Mon, 12/03/2018 - 16:55 By: icasl

The inherent performance benefits of using GaN over silicon in power electronics switching circuits (with respect to faster switching speeds, higher power density, and higher power efficiency) have been discussed previously by Milan et al.; yet, little is shown to support the sonic advantages or disadvantages of using GaN in Class D audio. It is shown by Meneghesso et al. that the dynamic on-state resistance of GaN-HEMTs is related to a higher rate of quantum traps at the gate-drain surface and also in the buffer region. It is also shown that for a signal amplifying circuit, the generation and recombination of carriers can be characterized by low frequency noise within the audio band of either a brown (1/f^2) or pink (1/f) noise color. Because of this, it was expected that GaN HEMTs would have a significantly poorer total harmonic distortion (THD) figures than that of silicon MOSFETs in audio applications. Furthermore, previous work by Chung et al. and Duraij et al.  do not confirm or disprove this assertion; therefore, this work began to further explore any sonic drawbacks of using GaN in Class D audio over the traditional silicon MOSFETs.