| 摘要 |
PURPOSE:To open and close an intermittent phase locked loop to reduce the power consumption by providing a switch between a variable LPF and a phase comparator for control. CONSTITUTION:The function of a phase locking oscillator is obtained when a switch 9 and a power supply switch 10 are turned on by the control signal given from a control signal line 11. When these switches are off, no power is supplied to a reference oscillator 4, frequency dividers 2 and 5 and a phase comparator 3. However the output voltage charged to a variable LPF8 in a synchronous mode is held as it is and then supplied to a voltage control oscillator 1. If the oscillation freuency of the oscilltor 1 has a shift from the frequency obtained in the synchronous mode when both switches 9 and 10 are turned on, the sag-shaped voltage is supplied for charging/discharging of the LPF8. Here the cut-off frequency of the LPF8 is set at a high level at first and then lowered gradually to smooth and supply it to the oscillator 1. Thus the variance can be suppressed for the oscillation frequency of the oscillator 1 despite an intermittent action. |
