摘要 |
<p>PURPOSE:To suppress dispersion of an oscillating frequency by cancelling the effect of a voltage difference of both threshold voltages of a Schmitt circuit onto the oscillating frequency. CONSTITUTION:A voltage difference of high and low threshold voltages of a Schmitt circuit 8 is led by a voltage difference detection section 15 and the voltage difference is converted into a current by a voltage current conversion section 16. Then the converted current and a control current are multiplied by a current multiplier section 17 and an output current of positive negative variable current sources 3, 4 of a charge pump circuit 2 is variably controlled based on the product of the currents. Thus, the effect of the voltage difference of both threshold voltages of the Schmitt circuit 8 onto the oscillating frequency is cancelled. Then even when both threshold voltages of the Schmitt circuit 8 are fluctuated due to the operating environmental condition or the like, the fluctuation in the oscillating frequency is suppressed.</p> |