| 摘要 |
PURPOSE:To make it unnecessary to execute an adjustment, and to secure a desired characteristic by using a variable capacity capacitor as a capacitor, controlling a variable capacitor of an electronic circuit by a phase detecting output obtained by a phase lock loop circuit, and absorbing a variance of a characteristic of the electronic circuit. CONSTITUTION:A reference signal of a prescribed frequency f0 outputted from a reference oscillator 16, and a signal of a frequency (f) outputted from a voltage control oscillator 18 are supplied to a phase detector and brought to a phase detection, a detected output voltage is smoothed by a lowpass filter 22 and an unnecessary component is eliminated, and it is supplied as a control voltage to the voltage control oscillator 18. In the voltage control oscillator 18, a variable capacity capacitor is controlled by this control voltage, and an electrostatic capacity of this variable capacity capacitor is set so that its oscillation frequency (f) becomes equal to the frequency f0 of the reference signal. That is to say, the electrostatic capacity of the variable capacity capacitor is varied by the control voltage, the frequency (f) and f0 are made to coincide with each other, and a variance of the resistance value and the electrostatic capacity is absorbed by the variable capacity capacitor. In this way, an electronic circuit which requires no adjustment from the outside can be converted to an IC. |
