| 摘要 |
PURPOSE:To accelerate response speed and to shorten setting time by providing a circuit to store the data of a control voltage to an oscillation frequency and a circuit to add a control voltage executing D/A conversion to read data. CONSTITUTION:This device is equipped with a voltage controlled oscillator (VCO) 3 of which oscillation frequency is to be controlled by a control voltage VC and a phase comparator 1 to compare the phase of an output frequency from a progrramable devider 5 with the phase of a reference signal R and to output a control voltage VD. Further, the device is equipped with a RAM 6 to previously store the data of the control voltage VC with a frequency dividing ratio setting signal SD as a read address, a D/A converter 7 to execute digital/analog conversion to these data, and a sample/hold circuit 8 to sample/ hold this output and to output a second control voltage VC 2. The first control voltage VC 1 and the VC 2 are added, and the CVO 3 is controlled through an adder amplifier 9 to output the control voltage VC. Then, the phase of a feedback signal F frequency-dividing the transmission frequency of this VCO 3 is compared with that of the reference signal R. |
