| 摘要 |
<p>A method of easily controlling the free-running frequency of a voltage-controlled oscillator. A single-shot circuit (24) generates a signal of accurate pulse width by using the signal output from a reference oscillator in a frequency synthesizer (20). A frequency counter (28) operates in synchronism with a signal supplied from a VCO (10) within a period corresponding to the pulse width, and a latch circuit (30) holds a count that corresponds to the oscillation frequency of the VCO (10). When this count becomes out of a predetermined range, a CPU (34) varies the control voltage Vs applied to the VCO (10) so that the free-running frequency of the VCO (10) may fall within the predetermined range.</p> |
