Pulse width modulation method and digital analogue converter using the same

Abstract

In a pulse width modulation method of the present invention, a digital signal is modulated and a pulse width modulation signal is generated in a pulse width modulator by using a digital signal output unit and the pulse width modulator The pulse width modulation method includes: outputting to the pulse width modulator a first value corresponding to the input signal as a first digital signal at a first timing by the digital signal output unit; determining a limited value range based on the first value by the digital signal output unit; determining a second value corresponding to a new input signal by the digital signal output unit; judging whether or not the second value is included in the limited value range, and when the second value being judged to be included, outputting the second value to the pulse width modulator as a second digital signal, and when the second value being judged not to be included, outputting a value included in the limited value range to the pulse width modulator as the second digital signal at the second timing at which at least one cycle has elapsed from the first timing by the digital signal output unit; and modulating the pulse width of the second digital signal and generating the pulse width modulation signal, by the pulse width modulator.