| 摘要 |
PURPOSE:To ensure a stable and accurate action with a large conversion gain by generating a voltage level according to the time until the frequency of input signals is counted in response to the reference signal and the contents of the counting reach a specified value from the response to the reference signal. CONSTITUTION:As the reference signal (a) shifts to a low level, a counter 29 is reset with a falling detecton circuit 28 and starts to count the building of an input signal fc. As the counter 29 counts by N pulse, -RC output moves to a low level, halting the counting. On the other hand, after the shifting of the reference signal (a) to a low level, a reset switch S11 is turned on and the output (d) moves to 0 volt. Then, until the -RC output moves to a low level from the shifting of the reference signal (a) to a high level, the switch S12 is kept on to perform a voltage conversion. In response to the change of the -RC output to a low level, a swtich S13 is turned on to move the voltage of the output (d) to a hold capacitor C12. This eliminates malfunctioning due to temperature changes, secular changes thereby enabling accurate operation. |
