| 摘要 |
PROBLEM TO BE SOLVED: To improve the switching speed and to optimize the jitter and spurious reduction by forming a loop filter so as to secure the closed loop transmission characteristic of a closed loop part that is approximately identical to the Gaussian characteristic. SOLUTION: A loop filter 2 connects the single input of a phase comparator 1 to its output in response to the input of a PLL circuit. Then a voltage control oscillator VCO 3 is connected to the output of the filter 2. The output of the VCO 3 is branched out in response to the output of the PLL circuit and connected to the other input of the comparator 1 via a divider 4. That is, the PLL circuit generally includes a closed loop part which contains a transmission line consisting of the comparator 1, the filter 2 and the VCO 3 and a feedback line consisting of the divider 4. In this case, the filter 2 is formed so as to secure the closed loop transmission characteristic of the closed part that is approximately identical to the Gaussian characteristic. |
