| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a wideband modulation PLL with excellent modulation accuracy at low cost. <P>SOLUTION: To a PLL provided with a VCO 21, a frequency divider 22, a phase comparator 23, a charge pump 24 and a loop filter 25, modulation is performed by controlling the frequency division ratio of the frequency divider 22 and the VCO 21. The VCO 21 is provided with two control terminals for the PLL and for modulation, and a control signal generation part 28 generates the control voltage V<SB>tm</SB>of the VCO 21 on the basis of an input voltage V<SB>tl</SB>to the control terminal for the PLL and phase modulation data. At the time of adjusting a modulation degree, the control voltage V<SB>tm</SB>to the control terminal for the modulation of the VCO 21 is controlled, the input voltage V<SB>tl</SB>is measured, the modulation sensitivity of the frequency of the VCO 21 to V<SB>tm</SB>is calculated, and the modulation degree of the phase modulation data is adjusted on the basis of the obtained modulation sensitivity. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
