| 摘要 |
PURPOSE: To accurately control the frequency of a voltage controlled oscillator by driving at least one switching element in a switching network by a pulse width modulator. CONSTITUTION: A phase synchronizing loop consists of a phase detector PD, to which an external signal E1 is impressed as a guide signal, and a signal E2 drawn out from the voltage controlled oscillator O is impressed as a reference signal and the oscillator O to be controlled by the switching network M. At least one switching element CP in the network M is driven by a pulse width modulator PLM. Consequently, the frequency of the oscillator O can be accurately controlled, even when limited accuracy is exceeded due to the allowable quantity of capacitors C1 to CN in the network M. |
