A PWM controlling circuit includes a signal generator and two PWM controllers. The signal generator comprises an oscillator, a plurality of inverters, and two RC delay networks. The oscillator and the inverters are composed of elementary elements, respectively, such as diodes, resistors, inverters and...http://www.google.com.tw/patents/US5901054?utm_source=gb-gplus-share專利 US5901054 - Pulse-width-modulation control circuit
