| 摘要 |
<p>A phase synchronization circuit, for generating a clock signal from an input signal, has a VCO (11), a phase comparator (12) for comparing the phase of the input signal with that of an output signal of the VCO, and a loop filter (13) for receiving an output signal of the phase comparator and providing a control voltage for the VCO. The loop filter includes first and second voltage-current converters (14, 15) for receiving the output signal of the phase comparator; a capacitor (16) to be charged and discharged according to an output current of the first voltage-current converter; and a resistor (17) for converting the output signal of the second voltage-current converter into the control voltage for the VCO. The ratio between currents for the input and output stages of a current multiplier in each of the first and second voltage-current converters is changed according to a control current provided through a control terminal when the frequency of the input signal is changed, to thereby change a transconductance of the converters without changing a damping factor. In this way, the circuit speedily carries out phase synchronization without changing a damping factor even if the frequency of an input signal is changed. <IMAGE></p> |
