| 摘要 |
<p>PURPOSE:To obtain the oscillation output of a large duty rate by intermittently controlling a charging current to a second capacitor by means of a first switch corresponding to the oscillation output of a first relaxation oscillator so as to reduce the average charging current and increase charging time to the second capacitor. CONSTITUTION:In a state where the electric charge of the capacitor C2 is discharged, the voltage of the reverse input of a second differential amplifier 123 is lower than that of not-reverse input so that the output of the amplifier 123 comes into a state L. The charging current from a constant current source circuit QP10 is integrated by the capacitor C2 when the output of the relaxation oscillator 110 is L, but FETM 1 is in an off state at the time of the output of the relaxation oscillator 110 is H so that the electric charge collected at the capacitor C2 is kept being held so as to make the integrated voltage of C2 constant. Consequently, the charging current from the circuit 11 is made to flow intermittently by the output of the oscillator 110 so that the integrated voltage C2, namely the voltage of the not-reverse input of the second amplifier 123, is boosted gradually. The duty rate of the relaxation oscillator 120 is made 1:1000 to 2000 like this.</p> |
