Patent ID: 7423493

Claim:
A semiconductor integrated circuit device for wireless communication, comprising: oscillation means for having an ability of oscillations in a plurality of frequency bands; variable frequency dividing means for dividing a frequency of an output signal from the oscillator by a designated frequency dividing ratio; set frequency dividing means for dividing a predetermined frequency of a reference signal by a predetermined frequency dividing ratio; phase comparing means for comparing a phase of an output signal from the variable frequency dividing means with a phase of an output signal from the set frequency dividing means to detect a difference between the phases; filter means for generating a voltage according to an output from the phase comparing means; and loop means for controlling the voltage generated by a filter means controls oscillation frequencies of the oscillation means, wherein the semiconductor integrated circuit device further comprising: switch means for supplying a predetermined potential to the oscillator as a control voltage with the loop means open; band selection means for comparing the phase of the output signal from the variable frequency dividing means and the phase of the output signal from the set frequency dividing means in a state that the switch means supply the predetermined potential to the oscillator, and selects an oscillation frequency band of the oscillation means; and register means for accepting, in order to prevent wrong selection of the oscillation frequency band due to a time lag in releasing the variable frequency dividing means and the set frequency dividing means from being reset, setting of a value by which another oscillation frequency band different from the selected oscillation frequency band is selected.