Circuit for generating a reference signal

摘要

A compact, inexpensive circuit for generating several stable reference signals from several burst signals is provided. The circuit comprises a first oscillator using a quartz oscillator; a second oscillator with a variable oscillation frequency having a range broader than that of the first voltage-controlled oscillator; a first frequency divider for dividing a frequency of an output signal of the first oscillator by j; a second frequency divider for dividing a frequency of an output signal of the second oscillator by k; a first phase comparator for comparing a phase of an output signal of the first frequency divider with a phase of an output signal of the second frequency divider; a first lowpass filter for smoothing an output signal of the first phase comparator and returning the smoothed signal as feedback to a control terminal of the second oscillator; a second phase comparator for comparing a phase of an output signal of the second oscillator with a phase of the burst signal; and a second lowpass filter for smoothing an output signal of the second phase comparator and returning the smoothed signal as feedback to a control terminal of the first oscillator. The continuous reference signal with the desired frequency is obtained from the output signal of the second oscillator.