| 摘要 |
PROBLEM TO BE SOLVED: To shorten a time to match frequencies of a reference signal to a signal to be compared. SOLUTION: An oscillating circuit C outputs the reference signal. A comparator A outputs a high level or low level voltage responding to a difference in electric potential between a + terminal and a - terminal. A frequency-voltage conversion circuit FV1 converts a frequency of an output signal from a dividing circuit D into a voltage for an input to the -terminal of the comparator A, Transistors Tr1 and Tr2 composes a charge pomp to charge a condenser included in a low-pass filter LF to be operated differentially by an output from the comparator A. The filter LF converts an output from the pomp into a DC current. A voltage controlled oscillating circuit VCO controls a frequency of an output signal responding to an output from the filter LF. The circuit D divides an output from the circuit VCO. |
