I've posted the following question to the sci.electronics.design groups. Some friendly people answered to my stupid question. But I didn't statisfy the answers. So I posted again here. Can you help me?
Question
-------------------------------------------------------------------------------------------------------------- Today I'd like to ask some basic question (the group title is basic). As is shown in the title, I don't exactly know why we use the PWM. I think that all the works PWM can do can be done by the DAC and linear power amplifier. Of course, the price may be up. But then I am curious again that the price is the only reason for us to use the PWM scheme rather than analog scheme. Can anybody tell me the exact reason for the PWM. Any kinds of Web site or material for studying shall be always welcomed~!