| 摘要 |
PURPOSE:To correct the conversion gain characteristics of a voltage control oscillator by varying the cut off frequency of a low-pass filter by applying the output control signal of a voltage generator to it. CONSTITUTION:Between phase detector 2 and voltage control oscillator 4, voltage cut-off frequency variable low-pass filter 9 is provided which operates by being supplied as a control signal with a signal from voltage generator 8 and corrects equivalently the conversion gain and variation characteristics of oscillator 4, thereby constituting the phase control circuit. In a range where the oscillation frequency of oscillator 4 increases according to a rise in the output voltage of generator 8 while conversion gain K0 lowers, the cut-off frequency of filter 9 is increased to make constant KF(s) of equation (2) expressing the stationary characteristics of the system when phase angle variation thetar changes by DELTAthetar in the stages resulting in the suppression of the variation in stationary characteristics attending on variation in oscillation frequency, so that characteristic variation of the circuit can be prevented. |
