| 摘要 |
<p>PURPOSE:To obtain a stable operating speed by comparing an oscillating period of a ring oscillating circuit with a reference value, detecting its shift, controlling a current flowing to a logical circuit group and a power supply voltage applied to the logical circuit group so as to eliminate variation of delay time. CONSTITUTION:A ring oscillator 6 is oscillated at a period in response to the delay time on an integrated circuit 5 and its output S6 is fed to an input of a counter 1. An output S1 of the counter 1 is compared with a prescribed reference value at a comparator 2 and when the output is less than the reference value, the comparator outputs a high level signal and when the output is the reference value or over, the comparator output a low level signal. The compared output is fed to a latch circuit 3, the output of the circuit 3 is integrated (4), the output S4, the output S4 is fed to the base of a transistor Q4 through a differential amplifier 7 so as to control a power supply voltage VDD of the integrated circuit 5.</p> |
