Communication semiconductor integrated circuit device and wireless communication system

• US 20030203720A1
• Filed: 04/16/2003
• Published: 10/30/2003
• Est. Priority Date: 04/26/2002
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Renesas Technology Corporation (Renesas Electronics Corporation)
• Inventors: Uozumi, Toshiya, Kasahara, Masumi, Oosawa, Hirotaka, Kurakami, Noriyuki
• Granted Patent: US 7,146,143 B2
• Time in Patent Office: Days
• US Class Current: 455/84
• CPC Class Codes: H03L 7/0891 the up-down pulses controlling source and sink current generators, e.g. a charge pump
• CPC Class Codes: H03L 7/101 using an additional control signal to the controlled loop oscillator derived from a signal generated in the loop H03L7/113, H03L7/187 take precedence
• CPC Class Codes: H03L 7/107 using a variable transfer function for the loop, e.g. low pass filter having a variable bandwidth
• CPC Class Codes: H03L 7/193 the frequency divider/counter comprising a commutable pre-divider, e.g. a two modulus divider

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.

Claims

1. 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 voltage in response to the phase difference detected by the phase detector; and

an oscillator which can oscillate on the basis of a voltage of a filter capacitor charged/discharged by the charge pump, comprising;

storing means for storing frequency information measured of said oscillator;

a frequency band determining circuit for comparing the measured frequency information stored in said storing means with said designated frequency information, and generating a signal for designating an oscillation frequency band of said oscillator;

a voltage generating circuit for generating a voltage applied to said filter capacitor or the oscillator on the basis of the measured frequency adapted to an oscillation frequency band determined by said frequency band determining circuit stored in said storing means and said designated frequency information;

control voltage switching means which acts so that a voltage according to an output of said charge pump or a voltage generated by said voltage generating circuit is selectively supplied as a control voltage of said oscillator; and

a control circuit for performing a switching control of said control voltage switching means,

wherein at start of operation of said PLL circuit, a voltage generated by said voltage generating circuit is supplied as an initial voltage to either said filter capacitor or said oscillator by said control voltage switching means to perform a pull-in operation, and said control voltage switching means is switched to supply a voltage according to an output of the charge pump to said oscillator to lock a PLL loop.

2. The communication semiconductor integrated circuit device according to claim 1, wherein a control voltage which is closest to the set frequency is determined on the basis of a frequency difference between the maximum frequency of said selected band and the set frequency and a frequency variable range of the selected band, and the control voltage is supplied by said control voltage switching means.

3. The communication semiconductor integrated circuit device according to claim 1, wherein at the time of measuring frequency of an oscillation signal of said oscillator, a predetermined voltage generated by said voltage generating circuit is supplied to said filter capacitor or said oscillator.

4. The communication semiconductor integrated circuit device according to claim 1, further comprising a frequency counter capable of measuring oscillation frequency of said oscillator,

wherein said control circuit makes said oscillator oscillate by a predetermined direct-current voltage supplied from said control voltage switching means in a state where said PLL circuit is in an open loop state, measures the frequency in each of predetermined frequency bands by said frequency counter, stores the measured frequencies into said storing means and, at the time of operating said PLL circuit in a closed loop, makes said oscillator oscillate in said designated frequency band on the basis of a signal from said frequency band determining circuit.

5. The communication semiconductor integrated circuit device according to claim 4, further comprising a counter circuit for dividing frequency of an oscillation signal, which is provided between said oscillator and said phase comparator, the counter circuit also serving as a frequency counter used at the time of said frequency measurement.

6. The communication semiconductor integrated circuit device according to claim 5,

wherein said counter circuit includes:

a frequency divider capable of switching a frequency division ratio;

a first programmable counter capable of computing a value corresponding to a quotient obtained by dividing frequency of a signal to be output from said oscillator by frequency of said reference signal and further dividing the resultant by one of frequency division ratios of said frequency divider; and

a second programmable counter capable of computing a value corresponding to a remainder of said division, and

wherein a value computed by said first programmable counter is stored in said storing circuit.

7. The communication semiconductor integrated circuit device according to claim 6, wherein said frequency band determining circuit compares measured frequency information stored in said storing means and frequency information set in said first and second programmable counters to generate a signal for designating the oscillation frequency band of said oscillator.

8. The communication semiconductor integrated circuit device according to claim 1, further comprising:

a first mixer for mixing an oscillation signal output from said PLL circuit or a signal obtained by dividing frequency of the oscillation signal with a reception signal, thereby obtaining a demodulated signal; and

a second mixer for mixing the oscillation signal output from said PLL circuit or a signal obtained by dividing frequency of the oscillation signal with a transmission signal, thereby obtaining a signal of a frequency corresponding to a frequency difference.

9. The communication semiconductor integrated circuit device according to claim 1, further comprising

a third mixer for mixing an oscillation signal output from said PLL circuit with a detection signal of the power amplifier, thereby obtaining a frequency-converted signal.

10. A wireless communication system comprising:

a communication semiconductor integrated circuit device; and

a baseband circuit,

the 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 voltage in response to the phase difference detected by the phase detector; and

an oscillator which can oscillate in a plurality of frequency bands on the basis of a voltage of a filter capacitor charged/discharged by the charge pump;

storing means for storing frequency information measured in each of predetermined frequency bands of said oscillator;

a frequency band determining circuit for comparing the measured frequency information stored in said storing means with said designated frequency information, and generating a signal for designating an oscillation frequency band of said oscillator;

a voltage generating circuit for generating a voltage applied to said filter capacitor or the oscillator on the basis of the measured frequency adapted to an oscillation frequency band determined by said frequency band determining circuit stored in said storing means and said designated frequency information;

control voltage switching means for selectively supplying a voltage according to an output of said charge pump or a voltage generated by said voltage generating circuit as a control voltage of said oscillator; and

a control circuit for performing a switching control of said control voltage switching means,

said communication semiconductor integrated circuit device being constituted such that, at start of operation of said PLL circuit, a voltage generated by said voltage generating circuit is supplied as an initial voltage to either said filter capacitor or said oscillator by said control voltage switching means to perform a pull-in operation, and said control voltage switching means is switched to supply a voltage according to an output of the charge pump to said oscillator to lock a PLL loop,

said baseband circuit extracting data from a reception signal down-converted to a desired frequency by the communication semiconductor integrated circuit device and converting transmission data to I and Q signals,

wherein said designated frequency information is supplied from said baseband circuit to said communication semiconductor integrated circuit device.

11. The wireless communication system according to claim 10, further comprising:

a phase control loop for controlling a phase of a carrier wave output from an oscillator for transmission; and

an amplitude control loop for controlling amplitude of a transmission output signal output from a power amplifier,

wherein transmission in a first modulation mode for performing phase modulation and transmission in a second modulation mode for performing phase and amplitude modulation can be performed, and

wherein transmission/reception according to a communication method using two or more frequency bands including at least a GSM method of a 900 MHz band can be performed.

12. 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 voltage generating circuit for generating a voltage in response to the phase difference detected by the phase detector; and

an oscillator which can oscillate on the basis of a voltage of said voltage generating circuit, comprising;

storing means for storing frequency information measured of said oscillator;

a frequency band determining circuit for comparing the measured frequency information stored in said storing means with said designated frequency information, and generating a signal for designating an oscillation frequency band of said oscillator;

a voltage generator for generating a voltage applied to said oscillator on the basis of the measured frequency adapted to an oscillation frequency band determined by said frequency band determining circuit stored in said storing means;

control voltage switching means which acts so that a voltage generated by said voltage generating circuit or a voltage generated by said voltage generator is selectively supplied as a control voltage of said oscillator; and

a control circuit for performing a switching control of said control voltage switching means,

wherein by said control voltage switching means, a voltage generated by said voltage generator is supplied to said oscillator and, after that, a voltage generated by said voltage generating circuit is supplied to said oscillator.

13. The communication semiconductor integrated circuit device according to claim 12, wherein a control voltage which is closest to the set frequency is determined on the basis of a frequency difference between maximum frequency of said selected band and the set frequency and a frequency variable range of said selected band, and the control voltage is supplied by said control voltage switching means.

14. The communication semiconductor integrated circuit device according to claim 12, wherein at the time of measuring frequency of an oscillation signal of said oscillator, a predetermined voltage generated by said voltage generator is supplied to said oscillator.

15. The communication semiconductor integrated circuit device according to claim 12, further comprising a frequency counter capable of measuring oscillation frequency of said oscillator,

wherein said control circuit makes said oscillator oscillate by a predetermined direct-current voltage supplied from said control voltage switching means in a state where said PLL circuit is in an open loop state, measures the frequency in each of predetermined frequency bands by said frequency counter, stores the measured frequencies into said storing means and, at the time of operating said PLL circuit in a closed loop, makes said oscillator oscillate in said designated frequency band on the basis of a signal from said frequency band determining circuit.

16. The communication semiconductor integrated circuit device according to claim 15, further comprising a counter circuit for dividing frequency of an oscillation signal from said oscillator, which is provided between said oscillator and said phase comparator, the counter circuit also serving as a frequency counter used at the time of said frequency measurement.

17. The communication semiconductor integrated circuit device according to claim 16,

wherein said counter circuit includes:

a frequency divider capable of switching a frequency division ratio;

a first programmable counter capable of computing a value corresponding to a quotient obtained by dividing frequency of a signal to be output from said oscillator by frequency of said reference signal and further dividing the resultant by one of frequency division ratios of said frequency divider; and

a second programmable counter capable of computing a value corresponding to a remainder of said division, and

wherein a value computed by said first programmable counter is stored in said storing circuit.

18. The communication semiconductor integrated circuit device according to claim 17, wherein said frequency band determining circuit compares measured frequency information stored in said storing means with frequency information set in said first and second programmable counters, to generate a signal for designating the oscillation frequency band of said oscillator.

19. The communication semiconductor integrated circuit device according to claim 12, further comprising:

a first mixer for mixing an oscillation signal output from said PLL circuit or a signal obtained by dividing frequency of the oscillation signal with a reception signal, thereby obtaining a demodulated signal; and

a second mixer for mixing the oscillation signal output from said PLL circuit or a signal obtained by dividing frequency of the oscillation signal with a transmission signal, thereby obtaining a signal of a frequency corresponding to a frequency difference.

20. The communication semiconductor integrated circuit device according to claim 12, further comprising:

a third mixer for mixing an oscillation signal output from said PLL circuit with a detection signal of the power amplifier, thereby obtaining a frequency-converted signal.

21. A wireless communication system comprising:

a communication semiconductor integrated circuit device; and

a baseband circuit,

the 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 voltage generating circuit for generating a voltage in response to the phase difference detected by the phase detector; and

an oscillator which can oscillate in a plurality of frequency bands on the basis of a voltage of said voltage generating circuit,

storing means for storing frequency information measured in each of frequency bands of said oscillator;

a frequency band determining circuit for comparing the measured frequency information stored in said storing means with said designated frequency information and generating a signal for designating an oscillation frequency band of said oscillator;

a voltage generator for generating a voltage applied to said oscillator on the basis of the measured frequency adapted to an oscillation frequency band determined by said frequency band determining circuit stored in said storing means;

control voltage switching means for selectively supplying, as a control voltage of said oscillator, a voltage generated by said voltage generating circuit or a voltage generated by said voltage generator; and

a control circuit for performing a switching control of said control voltage switching means,

said communication semiconductor integrated circuit device being constituted such that, by said control voltage switching means, a voltage generated by said voltage generator is supplied to said oscillator and, after that, a voltage generated by said voltage generating circuit is supplied to said oscillator,

said baseband circuit extracting data from a reception signal down-converted to a desired frequency by the communication semiconductor integrated circuit device,

wherein said designated frequency information is supplied from said baseband circuit to said communication semiconductor integrated circuit device.

22. The wireless communication system according to claim 21, further comprising:

a phase control loop for controlling a phase of a carrier wave output from an oscillator for transmission; and

an amplitude control loop for controlling amplitude of a transmission output signal output from a power amplifier,

wherein transmission in a first modulation mode for performing phase modulation and transmission in a second modulation mode for performing phase and amplitude modulation can be performed, and transmission/reception according to a communication method using two or more frequency bands including at least a GSM method of a 900 MHz band can be performed.