| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a frequency synthesizer in which a frequency can be finely set over a wide band and which has a wide frequency pull-in range. <P>SOLUTION: A PLL performs the quadrature detection of a sinusoidal signal having an output frequency of a voltage-controlled oscillation unit and uses a vector which rotates at a difference frequency (speed) between the output frequency and a frequency of a frequency signal used for the detection. A frequency pull-in means integrates a first constant for increasing the output frequency as a voltage for pull-in when a control voltage from the PLL to the voltage-controlled oscillation unit is larger than a set range set in advance and integrates a second constant for decreasing the output frequency as the voltage for pull-in when the control voltage is smaller than the set range. An addition means adds the control voltage from the PLL and the voltage for pull-in from the frequency pull-in means and outputs the addition result to the voltage-controlled oscillation unit. <P>COPYRIGHT: (C)2009,JPO&INPIT |
