Mosfets used in class D amps are non-linear, and almost always N- channel configuration, either half-bridge (Hypex) or full bridge (Icepower). I'm not sure why there is no complementary pair designs. All N-channel require charge-pump to provide voltage for the upper transistor, since its gate voltage is referenced to source voltage (changing output voltage). Advantage of GaN transistors, as far as I know, is in the switching speed and not in the linearity, required for class A or A/B.
In general Mosfet transistors are designed into two separate categories - linear Mosfets and switching Mosfets. Mosfets used in class D amps are pretty bad for class A or A/B applications.
In general Mosfet transistors are designed into two separate categories - linear Mosfets and switching Mosfets. Mosfets used in class D amps are pretty bad for class A or A/B applications.