Communication semiconductor integrated circuit device and wireless communication system
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Abstract
The invention provides a communication semiconductor integrated circuit device (RF IC) capable of pulling in the frequency of a PLL circuit to a desired set frequency at high speed even in the case where a frequency settable range of the PLL circuit is wide without providing a current source other than a current source for charging and discharging in an normal operation. An oscillator as a component of a PLL circuit is constructed so as to be operative in a plurality of bands. In a state where a control voltage of the oscillator is fixed to a predetermined value, an oscillation frequency of the oscillator is measured in each of bands and stored in a storing circuit. A set value for designating a band supplied at the time of PLL operation is compared with the stored measured frequency value. From a result of comparison, a band to be actually used in the oscillator is determined, and a frequency difference between the maximum frequency of the selected band and the set frequency is obtained. Further, a control voltage closest to the set frequency is determined on the basis of the frequency difference and the frequency variable range of the selected band and the control voltage is applied to the oscillator to start oscillating operation. After that, a PLL loop is closed and locked.
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Citations
30 Claims
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1-22. -22. (canceled)
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23. A semiconductor integrated circuit device for a radio communication device comprising:
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a phase locked loop circuit which includes a phase detection circuit which detects a phase difference between a reference signal having a predetermined frequency and a feedback signal which is an output signal of the phase locked loop circuit, a signal generation circuit which generates a first voltage in response to phase difference information signals from the phase detection circuit, an oscillation circuit which generates the output signal responding to a voltage of a filter that is charged or discharged by the signal generation circuit and which generates the output signal in accordance with desired frequency information;
a measuring circuit which measures a frequency of the output signal and outputs first frequency information which includes the frequency of the output signal;
a band selection circuit which selects an oscillation frequency band from a plurality of frequency bands by comparing the desired frequency information and the first frequency information and which generates a band selection signal;
an initial voltage generating circuit which generates a second voltage based on the band selection signal; and
a switching circuit which elects the second voltage or the first voltage for supplying to the filter or the oscillation circuit, wherein the switching circuit elects the second voltage at a beginning of operation of the phase locked loop circuit to perform a pull-in operation, and the switching circuit is switched to supply the first voltage to the oscillation circuit or the filter to lock the phase locked loop circuit after the pull-in operation. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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Specification