Communication semiconductor integrated circuit device and a wireless communication system

A semiconductor integrated circuit device for wireless communication, comprising:

• a clock generation means for generating a clock signal in response to an external set signal, wherein the clock generation means includes an oscillator which oscillates the clock signal in a plurality of frequency bands, a phase detector which detects a difference between a phase of the clock signal and a phase of a reference signal, a charge pump which receives an output of the phase detector, and a loop filter which generates a control voltage of the oscillator;
• a voltage supply means for supplying a set voltage to the loop filter;
• a switch means for switching the output of the charge pump and the set voltage;
• a frequency divide means for dividing the clock signal in accordance with an external set signal and supplying a divided clock signal to the phase detector;
• a counter means for counting a frequency of the clock signal and outputting a count value signal;
• and
• a selection means for selecting a frequency band from the plurality of frequency bands of the oscillator in accordance with the external set signal and the count value signal when the set voltage is supplied to the loop filter via the switch means.