| 摘要 |
PURPOSE:To obtain the output signal of a wide band while securing the satisfactory phase noise characteristic by controlling a narrow band voltage control oscillator and three dividers, to reduce the circuit scale by omitting plural voltage control oscillators, and to reduce the deterioration of the signal. CONSTITUTION:The output signal of a reference signal oscillator 1 is divided into 1/N1 pieces by a 1st frequency divider 2, and the output signal of a voltage control oscillator 5 is divided into 1/N2 pieces by a 2nd frequency divider 6 respectively. Then the output signals of both frequency dividers 2 and 6 are compared with each other by a phase comparator 3, and the obtained phase signal is integrated by an integrator 4. This integrated signal is fed back to the oscillator 5 and a stable output signal having the phase synchronization with the oscillator 1 is obtained. Then the output signal of the oscillator 5 is divided into 1/N3 pieces by a 3rd frequency divider 7 so that a desired output signal is produced. In such conditions, the multiplication value of the division ratio between both dividers 2 and 7 is set constant for the simplification of the control. In addition, the division value is set as N3>N1 or N1>N3 so as to reduce the frequency variable range of the oscillator 5 in order to obtain a satisfactory phase noise characteristic. |
