| 摘要 |
PROBLEM TO BE SOLVED: To provide the PLL circuit for tuner in which excellent phase noise characteristic is realized over a tuning frequency of a wide range. SOLUTION: An output of an oscillation circuit 10-1 connects to ground via a 1st varactor diode 10-2, a primary side of a coupling circuit 10-3, and a 2nd varactor diode 10-4, a circuit connecting to a 3rd varactor diode 10-6 is provided at connecting point between the 1st varactor diode 10-2 and the primary side of the coupling circuit 10-3 and ground. A PLL IC 10-5 includes a D/A converter 10-8 that converts digital input data into a control voltage for rough tuning and gives the voltage to a connecting point and a fine-tuning control voltage is fed to the 3rd varactor diode 10-6 via a phase loop filter 10-7. |
