REFERENCE FREQUENCY SIGNAL SOURCE

摘要

PROBLEM TO BE SOLVED: To provide a reference frequency signal source capable of adapting to different reference signals without drastically changing hardware.

SOLUTION: The reference frequency signal source includes: a frequency conversion circuit 10 that generates a clock signal and a local oscillation signal based on a reference signal and a control signal C that responds to the frequency fiof the reference signal; a DDS (Direct Digital Synthesizer) 2 that generates a frequency signal corresponding to frequency control data in synchronization with the clock signal; a filter 3 that suppresses unwanted wave components contained in the frequency signal from the DDS 2; a mixer 8 that frequency-mixes the local oscillation signal and the output signal of a voltage-controlled oscillator; a filter 9 that suppresses unwanted wave components contained in a mixed signal from the mixer 8; a phase comparator 5 that detects a phase difference between the frequency signal via the filter 3 and the mixed signal via the filter 9; a loop filter 6 that filters a phase-difference signal from the phase comparator 5; and the voltage-controlled oscillator 7 that generates the output signal in response to the phase difference signal via the loop filter 6.

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