With PWM, you lowpass filter the thing to ... something akin to DC then feed it to an A/D. It's all about approximating the area under a curve. They're everywh

With PWM, you lowpass filter the thing to ... something akin to DC then feed it to an A/D. It's all about approximating the area under a curve. They're everywhere - A/D are PWM, class D amps are PWM, power supplies...