| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a clock shaper wherein synchronism recovery is attained on an early stage when a fault occurs, and a prescribed synchronism can be secured even without a receiving clock signal or an auxiliary clock signal. <P>SOLUTION: The clock shaper is equipped with a first clock signal selecting part for inputting the receiving clock signal and the auxiliary clock signal from the outside and selecting any one clock signal, a crystal oscillation circuit which is oscillated in a predetermined frequency, a second clock signal selecting part for inputting the clock signal from the first clock signal selecting part and a clock signal from the crystal oscillation circuit and selecting any one clock signal, a voltage controlled oscillation circuit wherein a frequency is changed in accordance with a supplied control voltage for generating an output signal for feedback loop and output it, a phase comparing part for generating a phase difference signal based on the compared result of the output signal for feedback loop from the voltage controlled oscillation circuit and the clock signal from the second clock signal selecting part, and a loop filter for smoothing the phase difference signal and outputting it as the control voltage. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
