摘要 |
PURPOSE:To obtain a stable feedback signal and a phase comparator output, by changing over two constant-current sources in accordance with a digital value of a phase comparator output, and integrating its charge by an integral network. CONSTITUTION:An input signal Ei is phase-compared with a feedback signal Ef in a phase comparator 3, an output Ex is generated, a constant-current I1 and I2 are controlled by gates 9, 10 in accordance with a level of this Ex, and voltage of an output Ec of an operational amplifier 12 is varied. The output Ec of the operational amplifier 12 is compared with set voltage V by a comparator 13. Ec increases from ''0''V by changing over the gates 9, 10, and when it has attained to V, an output Et of the comparator 13 becomes high, and turns on an analog switch 15. By this operation, a capacitor 11 which has been charged is discharged instantaneously, Ec is reset to a ''0''V level, and Et becomes low simultaneously. |