| 摘要 |
In the path from the output of a charging pump to a control voltage terminal including the inside of a loop filter, voltage application means for applying a direct-current voltage of a predictable value to the control voltage terminal is given, resulting in a PLL circuit. In the PLL circuit, first, a fixed direct-current voltage is applied to the control voltage terminal from the voltage application means. The oscillation frequency of a voltage-controlled oscillator may be adjusted by making use of a trimming area as a oscillation frequency adjustment mechanism. Therefore, the oscillation frequency of the voltage-controlled oscillator can be quickly adjusted using fewer pieces of equipment.
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