Circuit having a multi-band oscillator and compensating oscillation frequency
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Accused Products
Abstract
A semiconductor integrated circuit device for communication is provided with a PLL circuit or the like formed therein, the PLL circuit which is capable of realizing the compensation of fluctuation due to temperature change, the inhibition of increase in the chip area and the ensurement of the performance margin, and which controls a VCO having multiple oscillation frequency bands. In the case where automatic calibration is performed by switching a switch to a side of a DC voltage source in the PLL circuit using a VCO having multiple oscillation bands, a tuning voltage (Vtune) of an RFVCO is fixed to a voltage value of a DC voltage source. However, since a temperature characteristic of canceling a VCO oscillation frequency is given to the DC voltage source, it is possible to minimize the influence on the band selection when a calibration table comes to no optimum one.
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Citations
42 Claims
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1-38. -38. (canceled)
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39. A method of correcting a voltage controlled oscillator for oscillating in a plurality of frequency bands, comprising:
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a setting step for setting said voltage controlled oscillator to a first frequency band;
a measuring step for measuring an oscillation frequency of said voltage controlled oscillator according to a predetermined control voltage;
a comparing step for comparing the measured value with a target reference frequency to determine whether or not the measured value matches the target reference frequency;
a re-measuring step for measuring a new measured value for selecting said first frequency band for oscillation of said voltage controlled oscillator when the measured value matches the target reference frequency, setting said voltage controlled oscillator to a new frequency band and measuring the oscillator output frequency at said predetermined control voltage to obtain a new measured value when the measured value does not match the target reference frequency; and
a repeating step for repeating said comparing step using the new measured value and said target reference frequency and acting on the result to either select said new frequency band for oscillation of said voltage controlled oscillator or setting said voltage controlled oscillator to another new frequency band and repeating the measure and comparing steps if necessary until a frequency band has been selected. - View Dependent Claims (40, 41, 42)
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Specification