| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a PLL circuit which can realize a PLL oscillator that can reduce the phase noise, due to reference leakage being fully suppressed and a loop band can be set in a wide band to the limit. <P>SOLUTION: The PLL circuit has a phase comparator 1, a 1st charge pump circuit 2, an LPF3, a VCO4, and a frequency divider 5, and the PLL loop formed. Furthermore, the PLL circuit comprises a 2nd charge pump circuit 6 which converts an error signal outputted from the phase comparator 1 into a current, and a control circuit 7a which compares the output of the 2nd charge pump circuit 6 with a reference value, if the output is larger than the reference value, and gradually decrease each output of the charge-pump circuit 2 and the charge-pump circuit 6, until the output becomes lower than the reference value. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
