| 摘要 |
PROBLEM TO BE SOLVED: To obtain the VCO featuring automatic variable PLL circuit which can have VCO features optimized over a wide oscillation frequency range and also has the stable VCO features irrelevantly to its manufacture variance without making the circuit constitution large even in case of IC-implementation. SOLUTION: This circuit is equipped with a voltage-controlled oscillator 11 which has plural VCO features and oscillates an output clock of frequency based upon selected VCO features and a VCO featuring switch 17 which switches VCO features to VCO features of high oscillation frequency when a window comparator 14 decides that an error signal is above a set range and to VCO features of low oscillation frequency when it is decided that the error signal is below the set range, and the voltage conversion gains of the respective VCO features need not be made unnecessarily high within the oscillation frequency range and are tolerant of disturbance. |
