In Reply to: Re: Pulse Width Modulation (PWM) for Audio posted by Jeffrey Furlong on 09/06/00 at 8:30 AM:
PWM for audio application
I have developed this circuit, with 200 kHz frequency switching, in discrete components. I know a little about this. It may help you.
This called class D amplifier, offers us with hi eficiency, because of its switching mode. In linear mode, the highest efficiency could be reached at 78%, but in class D amplifier, it can be 95% or more.
This efficiency obtained from usage of power switching devices, typically FET (I use mosfet), that operate only in two modes : ON or off. This is why, we have only ignorable losses, when this amplifier is drawing a "current" output. This losses come from Rds ON of the FET, and the filter output. Filter is used to re-obtain an audio analog information from PWM output of the amplifier.
So, if u want to build a low power (???) or a low voltage amplifier, you do not have make it with this class D amplifier. If we want to convert a sinusoidal voltage from a square voltage as the output of class D amplifier, we have to prepare a dc supply about twice of the peak sinusoidal wave we hope.
Thid is my comment about this pwm for audio, or class D amplifier. It will be very helpfull for me, if someone can give me suggestion about how to find more references about this class D amplifier. I has find so many informations, from www.TI.com, about this. Any others?