| 摘要 |
<p>PURPOSE: To reduce noise by providing pulse width modulators having the respective on-off cycles of which the phases are fixed at 180 deg. shifted from each other by a phased-locked loop. CONSTITUTION: A switch mode power supply device is equipped with switch mode power supply parts 16 and 17 having equal-duty cycles of which the phases are shifted at 180 deg. from each other and it is constructed of a switch 20 of a field effect transistor, a drive circuit 18 thereof and an inductance coil 22. Besides, it is equipped with an oscillator 12, a frequency bisecting circuit 34, a one-shot multivibrator 44 and FFs 14 and 15 and a voltage monitoring circuit 48 and, moreover, a phase-locked loop 45 is constructed of a phase detector 46, the voltage monitoring circuit 48, an adder 49, a voltage-controlled oscillator 32 and a frequency bisecting circuit 36. By this constitution, the power supply devices 16 and 17 of which the phases are shifted at 180 deg. from each other accurately are obtained and an output signal from an output 30 is made a non- harmonic as the result of precise phase locking.</p> |
