| 摘要 |
PURPOSE:To obtain stable pulse-width limitting even when the reference voltage of a converter varies by using a periodical signal wave-form as digital quantity, dividing the reference voltage by resistance circuit and giving the voltage level of control signals an upper limit or a lower limit. CONSTITUTION:A periodical signal wave-forms are generated successively as digital quantities from a function generator 20, and the wave-forms are changed into analog in a D/A converter 22 and modulation signals vm are obtained. On the other hand, the reference voltage Vref of the D/A converter 22 determining the amplitude of modulation signals is potential-divided by a resistance dividing circuit 29, and the voltage level of control signals Vc is given the upper limit VM or the lower limit Vm. Consequently, the pulse width of output signals is given the lower limit or the upper limit. Accordingly, the amplitude of the modulation signals vm does not vary due to the scatter of parts used and a temperature change. |
