Quote Originally Posted by Clive View Post
It's only words so not really of any importance but...is there a solid definition of class d? People generally think of class d as denoting a digital amplifier when they are usually PWM. We can also think of "d" the as being a random letter which people then unfortunately ascribe to meaning digital. I think of class d as being predominantly PWM (switching) amps.
Clive

Wiki's answer to Class 'd'

The term "class D" is sometimes misunderstood as meaning a "digital" amplifier. While some class-D amps may indeed be controlled by digital circuits or include digital signal processing devices, the power stage deals with voltage and current as a function of non-quantized time. The smallest amount of noise, timing uncertainty, voltage ripple or any other non-ideality immediately results in an irreversible change of the output signal. The same errors in a digital system will only lead to incorrect results when they become so large that a signal representing a digit is distorted beyond recognition. Up to that point, non-idealities have no impact on the transmitted signal. Generally, digital signals are quantized in both amplitude and wavelength, while analog signals are quantized in one (e.g. PWM) or (usually) neither quantity.