| 摘要 |
PROBLEM TO BE SOLVED: To provide a signal generating circuit improved in spurious suppression performance and capable of using a PLL circuit realized with a small capacitance. SOLUTION: A PLL circuit 15 suppresses a spurious component generated by a DDS circuit and a C/A converter 2. An output from a phase comparator 4 of a PLL circuit 15 is distributed into two paths, the one component is used to apply frequency control to a VCO via gain control and the other component is used to apply frequency control to the VCO via a primary filter so as to act a circuit processing the one component like a lead filter and to act a circuit processing the other component like a lag filter. The gain and the time constant of the primary filter are changed depending on color or black/white discrimination to improve the suppression performance and to reduce a capacitance of an integration capacitor C. |
