Patent ID: 7146143

Claim:
A communication semiconductor integrated circuit device comprising a PLL circuit capable of outputting an oscillation signal of a frequency according to designated frequency information, including: a phase detector for detecting a phase difference between a reference signal of a predetermined frequency and a feedback signal; a charge pump for generating a first voltage in response to the phase difference detected by the phase detector; and an oscillator which can oscillate on the basis of a second voltage of a filter capacitor charged/discharged by the charge pump, comprising: storing means for storing frequency information measured of the oscillator; a frequency band determining circuit for comparing the measured frequency information stored in the storing means with the designated frequency information, and generating a signal for designating an oscillation frequency band of the oscillator; a voltage generating circuit for generating a third voltage applied to the filter capacitor or the oscillator on the basis of the measured frequency adapted to an oscillation frequency band determined by the frequency band determining circuit stored in the storing means and the designated frequency information; control voltage switching means which acts so that the first voltage according to an output of the charge pump or the third voltage generated by the voltage generating circuit is selectively supplied as a control voltage of the oscillator; and a control circuit for performing a switching control of the control voltage switching means, wherein at start of operation of the PLL circuit, the third voltage generated by the voltage generating circuit is supplied as an initial voltage to either the filter capacitor or the oscillator by the control voltage switching means to perform a pull-in operation, and the control voltage switching means is switched to supply the control voltage according to an output of the charge pump to the oscillator to lock a PLL loop.