| 摘要 |
A semiconductor integrated circuit with a PLL (Phase Locked Loop) built therein is used in a semiconductor integrated circuit for wireless communication. The PLL circuit generates an oscillation signal having a predetermined frequency, which is combined with a receive signal or a transmit signal for wireless communication. The PLL circuit includes a VCO capable of switching an oscillation frequency band, a variable divider, a loop filter and a phase comparator. An oscillation frequency of the VCO is controlled according to the difference in phase between a signal obtained by dividing the output of the VCO and a reference signal, and a discrimination circuit makes a decision as to a lead or delay of the phase of an output of the variable divider with respect to a reference signal having a predetermined frequency. An auto band selection circuit generates a signal for selecting a frequency band for the VCO.
|
