| 摘要 |
PURPOSE:To obtain a PWM signal while ensuring a minimum pulse width by generating a pulse signal of nearly 1/4 period based on a zero cross point of a triangle wave and using the said pulse signal so as to generate a minimum on/off pulse signal. CONSTITUTION:A triangle wave is inputted to a terminal S1, a comparator 16 detects a zero cross point, one-shot multivibrators 18a, 18b are activated to generate pulses SH1, SH2 having a minimum on/off width. After modulating sinusoidal waves Mu-Mw are inputted to absolute value circuits 23u-23w, the waves are converted into a rectangular wave by comparators 24u-24w. Whether or not the output passes through the gates 25u-25w is detected depending on whether the minimum on/off pulse signals SH1, SH2 are superimposed or not. A minimum on/off superimposing circuit 15 superimposes outputs of both circuits.
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