| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a PLL circuit whereby frequency deviation is eliminated in a produced signal while stabilizing its operation when a reference signal is switched. <P>SOLUTION: The PLL circuit includes: a phase comparator 1; an integrator circuit 2; a voltage-controlled oscillator 3; a frequency divider circuit 4; a selection circuit 7 for selecting either of two received reference signals 5, 6; and a phase difference elimination circuit 8 having a function of canceling a phase difference between the two reference signals, and the phase difference elimination circuit 8 includes: a signal input detection circuit 9 for monitoring the two received reference signals 5, 6 to detect whether or not the two received reference signals 5, 6 exist; a phase difference presence detection circuit 10 for detecting the presence / absence of the phase difference between the two received reference signals 5, 6; and a delay circuit 11 for delaying either of the two received reference signals 5, 6. <P>COPYRIGHT: (C)2004,JPO |
