| 摘要 |
<p>PURPOSE:To use a phase comparing circuit made into a one-chip IC to make switching between a reference signal and a phase synchronizing signal of this signal possible by connecting a frequency varying varicap of a variable frequency oscillating circuit to a power source and applying the phase comparison output as a difference of the power source voltage. CONSTITUTION:The cathode side of a varicap 66 of a variable frequency oscillating circuit 60 having an oscillation center frequency 4fSC is connected to a power supply terminal 67, and an output VL of a phase comparing circuit 20 is supplied to the connection point between the anode and a capacitor 64 through an LPF40. The oscillated output of the circuit 60 is supplied to a terminal B of a comparator 23 through a terminal 20b of the circuit 20 and an 1/N frequency dividing circuit 22, and the output of a quartz oscillating circuit 70 having an oscillation frequency 4fCK is supplied to a terminal A through a terminal 20a and a 1/M frequency dividing circuit 21. The output signal of the circuit 60 is supplied to a frequency dividing circuit 81 to obtain a subcarrier SC having a frequency fSC, and the output signal of the circuit 70 is supplied to a frequency dividing circuit 82 to obtain a clock CK and horizontal and vertical synchronizing pulses.</p> |
