| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a PLL control system capable of suppressing variance in loop band even when charge pump currents are set for each band of a VCO. <P>SOLUTION: The PLL control system includes: a TCX0 8; a frequency divider B8; the VCO 4 having a plurality of bands; a frequency divider A5; a phase comparator 6 which compares two frequency-division signals of the frequency dividers A5 and B8 with each other; a loop filter 2 which outputs a voltage to the VCO 4; a charge pump circuit 3 which supplies a current to the loop filter 2 according to the comparison signal of the phase comparator 6; a precharging circuit 1 which precharges the loop filter 2; and a control section 9, the control section 9 discretely controlling the precharging by the precharging circuit 1 based upon discrete information preset in accordance with the plurality of bands. <P>COPYRIGHT: (C)2008,JPO&INPIT |
