PLL frequency synthesizer circuit and frequency tuning method thereof
First Claim
1. A PLL frequency synthesizer circuit integrated on a semiconductor integrated circuit, comprising:
- a voltage-controlled oscillator circuit provided with a capacitor, an inductor, and a variable capacitor element for oscillating using the resonance frequencies of the capacitor and inductor, for outputting the oscillation frequency signal of the variable capacitor element;
a negative feedback loop circuit configured to comprise the voltage-controlled oscillator circuit, capable of looping the signal output from the voltage-controlled oscillator circuit and performing a frequency acquisition operation for adjusting the frequency of the signal to a desired locking frequency;
a tuning circuit, connected to the loop circuit to receive the signal output, for performing tuning so that the oscillation frequency approaches the locking frequency, by modulating the capacitance value of the capacitor of the voltage-controlled oscillator circuit prior to the frequency acquisition operation; and
a reference potential application circuit for selectively applying a reference potential to the variable capacitor element of the voltage-controlled oscillator circuit during the tuning operation performed by the tuning circuit, the reference voltage application circuit is configured to switch between two types of electrical potentials to be applied to the variable capacitor element of the voltage-controlled oscillator circuit during the tuning operation.
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Accused Products
Abstract
A PLL frequency synthesizer circuit includes a voltage-controlled oscillator circuit provided with a capacitor, an inductor, and a variable capacitor element oscillating using the resonance frequencies of the capacitor and inductor, for outputting the oscillation frequency signal of a variable capacitor element, a negative feedback loop circuit capable of looping the signal output from the voltagecontrolled oscillator circuit and performing a frequency acquisition operation for adjusting the frequency of the signal to a desired locking frequency, a tuning circuit for performing tuning so that the oscillation frequency approaches the locking frequency, by modulating the capacitance value of the capacitor of the voltage-controlled oscillator circuit prior to the frequency acquisition operation, and a reference potential application circuit for applying a reference potential to the variable capacitor element of the voltage-controlled oscillator circuit during the tuning operation performed by the tuning circuit.
16 Citations
17 Claims
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1. A PLL frequency synthesizer circuit integrated on a semiconductor integrated circuit, comprising:
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a voltage-controlled oscillator circuit provided with a capacitor, an inductor, and a variable capacitor element for oscillating using the resonance frequencies of the capacitor and inductor, for outputting the oscillation frequency signal of the variable capacitor element; a negative feedback loop circuit configured to comprise the voltage-controlled oscillator circuit, capable of looping the signal output from the voltage-controlled oscillator circuit and performing a frequency acquisition operation for adjusting the frequency of the signal to a desired locking frequency; a tuning circuit, connected to the loop circuit to receive the signal output, for performing tuning so that the oscillation frequency approaches the locking frequency, by modulating the capacitance value of the capacitor of the voltage-controlled oscillator circuit prior to the frequency acquisition operation; and a reference potential application circuit for selectively applying a reference potential to the variable capacitor element of the voltage-controlled oscillator circuit during the tuning operation performed by the tuning circuit, the reference voltage application circuit is configured to switch between two types of electrical potentials to be applied to the variable capacitor element of the voltage-controlled oscillator circuit during the tuning operation. - View Dependent Claims (5, 6, 7, 8, 9)
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2. A PLL frequency synthesizer circuit integrated on a semiconductor integrated circuit, comprising:
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a voltage-controlled oscillator circuit provided with a capacitor, an inductor, and a variable capacitor element for oscillating using the resonance frequencies of the capacitor and inductor, for outputting the oscillation frequency signal of a variable capacitor element; a negative feedback loop circuit configured to comprise the voltage-controlled oscillator circuit, capable of looping the signal output from the voltage-controlled oscillator circuit and performing a frequency acquisition operation for adjusting the frequency of the signal to a desired locking frequency; a tuning circuit for performing tuning so that the oscillation frequency approaches the locking frequency, by modulating the capacitance value of the capacitor of the voltage-controlled oscillator circuit prior to the frequency acquisition operation; and a reference potential application circuit for applying a reference potential to the variable capacitor element of the voltage-controlled oscillator circuit during the tuning operation performed by the tuning circuit, wherein an element is used as the variable capacitor element having characteristics such that the voltage range in which the capacitor characteristics of the variable capacitor element vary in linear fashion is narrower than the absolute value of the voltage applied to the second terminal from the first terminal of the variable capacitor element. - View Dependent Claims (3)
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4. A PLL frequency synthesizer circuit integrated on a semiconductor integrated circuit, comprising:
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a voltage-controlled oscillator circuit provided with a capacitor, an inductor, and a variable capacitor element for oscillating using the resonance frequencies of the capacitor and inductor, for outputting the oscillation frequency signal of a variable capacitor element; a negative feedback loop circuit configured to comprise the voltage-controlled oscillator circuit, capable of looping the signal output from the voltage-controlled oscillator circuit and performing a frequency acquisition operation for adjusting the frequency of the signal to a desired locking frequency; a tuning circuit for performing tuning so that the oscillation frequency approaches the locking frequency, by modulating the capacitance value of the capacitor of the voltage-controlled oscillator circuit prior to the frequency acquisition operation; and a reference potential application circuit for applying a reference potential to the variable capacitor element of the voltage-controlled oscillator circuit during the tuning operation performed by the tuning circuit, wherein when the frequency variation amount of a step by which the oscillation frequency is switched by adjustment of the capacitance value is fvco_and the variation range of the oscillation frequency by voltage control is Δ
fvco, then the value of fvco_is set such that the following condition is satisfied;
fvco_step≦
Δ
fvco/4.
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10. A PLL frequency synthesizer circuit integrated on a semiconductor integrated circuit, comprising:
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a voltage-controlled oscillator circuit provided with a capacitor, an inductor, and a variable capacitor element for oscillating using the resonance frequencies of the capacitor and inductor, for outputting the oscillation frequency signal of the variable capacitor element; a negative feedback loop circuit configured to comprise the voltage-controlled oscillator circuit, capable of looping the signal output from the voltage-controlled oscillator circuit and performing a frequency acquisition operation for adjusting the frequency of the signal to a desired locking frequency; a tuning circuit, connected to the loop circuit to receive the signal output, for performing tuning so that the oscillation frequency approaches the locking frequency, by modulating the capacitance value of the capacitor of the voltage-controlled oscillator circuit prior to the frequency acquisition operation; and a reference potential application circuit for applying a reference potential to the variable capacitor element of the voltage-controlled oscillator circuit during the tuning operation performed by the tuning circuit, wherein the voltage-controlled oscillator circuit is provided with a plurality of capacitors, wherein the tuning circuit modulates the capacitance value used in the generation of the resonance frequency, by selecting any of the capacitors from among the plurality of capacitors. - View Dependent Claims (11, 12, 13)
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14. A method for tuning the oscillation frequency of a PLL frequency synthesizer circuit comprising:
- a voltage-controlled oscillator circuit provided with a capacitor, an inductor, and a variable capacitor element for oscillating using the resonance frequencies of the capacitor and inductor, for outputting the oscillation frequency signal of a variable capacitor element; and
a negative feedback ioop circuit configured to comprise the voltage-controlled oscillator circuit, capable of looping the signal output from the voltagecontrolled oscillator circuit and performing a frequency acquisition operation for adjusting the frequency of the signal to a desired locking frequency;
the frequency tuning method for a PLL frequency synthesizer circuit, the method comprising;performing a first tuning such that the oscillation frequency approaches the locking frequency, by modulating the capacitance value of the capacitor of the voltage-controlled oscillator circuit in a state in which one of two types of electrical potentials is applied to the variable capacitor element of the voltage-controlled oscillator circuit; and performing a second tuning such that the oscillation frequency approaches the locking frequency, by modulating the capacitance value of the capacitor of the voltage-controlled oscillator circuit in a state in which the other of the two types of electrical potentials is applied to the variable capacitor element of the voltage-controlled oscillator circuit, these steps being performed prior to the frequency acquisition operation. - View Dependent Claims (15, 16, 17)
- a voltage-controlled oscillator circuit provided with a capacitor, an inductor, and a variable capacitor element for oscillating using the resonance frequencies of the capacitor and inductor, for outputting the oscillation frequency signal of a variable capacitor element; and
Specification