| 摘要 |
PURPOSE:To quicken phase synchronization locking by keeping a damping constant to be a prescribed value even against the changeover of an input signal frequency with respect to the phase locked loop circuit used for clock recovery or the like. CONSTITUTION:A phase of the output signal of a voltage controlled oscillator 1 and the phase of an input signal are compared by a phase comparator 2 and its output is used for a control voltage of the voltage controlled oscillator 1 via a loop filter 3. The loop filter 3 of the phase locked loop circuit is provided with 1st and 2nd voltage current converters 4, 5, a capacitor 6 charged/ discharged by the output current of the 1st voltage current converter 4, and a resistor 7 receiving an output current of the 2nd voltage current converter 5, a ratio of a control current of the input stage of a current multiplier section being components of the 1st and 2nd voltage current converters 4, 5 to a control current of an output stage is selected corresponding to the changeover of the input signal frequency to select a conversion coefficient without changing a damping constant. |
