Like I said:

Quote:
switching 'on duration' and/or frequency can be modulated .... practical effect is a variable duty cycle.


There is no other way to do a digital amp. This is practically the definition of a digital amp. And PWM has had company for years - PFM. Now we can create a variety of hybreds, but the essence of the thing remains unchanged.

Creating waveforms with switching devices has been around longer than almost anyone here I'd bet.
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Charlie