Patent ID: 7847639

Claim:
A pulse width modulation device comprising: a control signal generating device that generates a step form control signal; a carrier generating device that generates a triangular wave carrier signal for pulse width modulation of said control signal; a comparison device that outputs a comparison signal as a result of comparison of said control signal and said carrier signal; a top/bottom signal generating device that generates a top/bottom signal when said carrier signal reaches the top or bottom of said triangular wave; an edge detection device that inputs said comparison signal and said top/bottom signal and is provided with an edge detection func on that generates an edge detection signal by detecting change of said comparison signal and wherein said edge detection signal inhibits said edge detection function and said top/bottom signal cancels inhibition of said edge detection function so that said edge detection signal is output; and a pulse generating device that outputs a pulse width modulation signal obtianed by pulse width modulation of said control signal by said carrier signal in accordance with said comparison signal, edge detection signal and said top/down signal.