| 摘要 |
PROBLEM TO BE SOLVED: To provide a frequency synthesizer where a voltage-controlled oscillator with an excellent C/N characteristic and having a wide variable frequency range is integrated at a low cost. SOLUTION: The frequency synthesizer comprising a reference frequency oscillator 4, a voltage-controlled oscillator 1, a 1st frequency divider 2, a 2nd frequency divider 4, a phase comparator 5 and a charge pump 6, is configured with the voltage-controlled oscillator 1 that has a resonance circuit configured with an LC resonance circuit element 22 connected to a varactor diode 21, whose capacitance varies with a voltage applied to a control voltage terminal of the voltage-controlled oscillator 1 and which is formed at least on a semiconductor substrate 20, and with a frequency adjustment means 30 that includes a control data generating section that outputs a signal to variably control the reactance of the resonance circuit, a reset signal generating section and a frequency detection section. |
