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US 7,148,764 B2Granted
Communication semiconductor integrated circuit device and a wireless communication system
AssigneesRenesas Technology Corp., TTPCOM Limited
InventorsMasumi Kasahara, Hirotaka Osawa, Robert Astle Henshaw
Life of this patent
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Abstract
In a communication semiconductor integrated circuit device, an oscillator (VCO 10) of a PLL circuit can operate in a plurality of frequency bands. With a control voltage (Vc) of the oscillator fixed to a predetermined value (VDC), an oscillation frequency of the oscillator is measured for each band to be stored in a storage (18). When the PLL operates, a setting value to specify a band is compared with the measured frequency values stored in the storage. As a result of the comparison, a band to be actually used by the oscillator is determined.
Claims10
A communication semiconductor integrated circuit device comprising:
- a phase-locked loop (PLL) circuit comprising an oscillator circuit for oscillating a signal in a plurality of frequency bands, a phase detection circuit configured to detect a difference between a phase of a reference frequency signal received from a reference oscillator circuit and a phase of said signal from said oscillator circuit, and charge pump and a filter capacitor for generating a voltage in response to output of said phase detection circuit;
- fixed voltage supply means for supplying a predetermined direct-current (dc) voltage as a control voltage of said oscillator circuit;
- a frequency counter, coupled to said oscillation circuit, for determining an oscillation frequency of said oscillator circuit;
- storage means for storing frequency information determined for each frequency band of said oscillator circuit;
- a control circuit which causes, in a state in which said PLL circuit is set to an open loop state, said oscillator circuit to conduct an operation of oscillation by a dc voltage from said fixed voltage supply means, to determine a frequency of the oscillation for each frequency band of said oscillator circuit, and causes said storage means to store the frequency.
2 more elements
A wireless communication system, comprising:
- a communication semiconductor integrated circuit device comprising:
- a phase-locked loop (PLL) circuit configured to generate an oscillation signal of a frequency according to specified frequency information, said PLL circuit comprising a phase detection circuit for detecting a phase difference between a frequency signal as a reference and a feedback signal, and a charge pump and a filter capacitor for generating a voltage in response to the phase difference detected by said phase detection circuit, and an oscillator circuit for oscillating a signal in a plurality of frequency bands according to a voltage of said filter capacitor;
- fixed voltage supply means capable of supplying a predetermined direct-current (dc) voltage as a control voltage of said oscillator circuit;
- a frequency counter capable of measuring an oscillation frequency of said oscillator circuit;
- storage means for storing frequency information measured for each frequency band of said oscillator circuit;
- a control circuit which causes, in a state in which said PLL circuit is set to an open loop state, said oscillator circuit to conduct an operation of oscillation by a dc voltage from said fixed voltage supply means, to measure a frequency of the oscillation for each frequency band of said oscillator circuit, and causes said storage means to store the frequency;
- and
- a frequency band decision circuit which compares the frequency information stored in said storage means with said specified frequency information and for generates a signal specifying an oscillation frequency band of said oscillator circuit, said control circuit causing, in a state in which said PLL circuit is set to an open loop state, said oscillator circuit to conduct an operation of oscillation by a dc voltage from said fixed voltage supply means, measuring a frequency of the oscillation for each frequency band of said oscillator circuit, causing said storage means to store the frequency, and causing, when said PLL is set to a closed loop state for operation, said oscillator circuit to conduct an operation of oscillation in said specified oscillation frequency band according to a signal from said frequency band decision circuit;
- and
- a baseband circuit for extracting data from a received signal down-converted to a desired frequency by said communication semiconductor integrated circuit device and for converting transmission data into an I signal and a Q signal,
- wherein the specified frequency information is fed from said baseband circuit to said communication semiconductor integrated circuit device.
8 more elements
Dependencies are inferred from the claim text.