Frequency synthesizer
First Claim
1. A frequency synthesizer apparatus comprising:
- a voltage controlled oscillator circuit that varies oscillation frequency thereof by a control voltage supplied thereto, the voltage controlled oscillator circuit including;
a variable capacitance element; and
a capacitor bank that includes a plurality of weighted capacitance elements and a plurality of switches controlled turned ON and OFF based on a plurality of control bit signals corresponding to the plurality of capacitance elements, respectively;
a phase comparator that performs phase comparison between an output signal fed back from the voltage controlled oscillator circuit and a reference signal supplied thereto, the output signal from the voltage controlled oscillator circuit being fed back directly or via a frequency divider to an input of the phase comparator;
a loop filter that generates a control voltage for supply to the voltage controlled oscillator circuit, based on a result of the phase comparison; and
a temperature compensation block that includes;
a first correction potential generation circuit that generates a correction potential for parasitic capacitance of the capacitor bank of the voltage controlled oscillator circuit;
a second correction potential generation circuit that generates a correction potential for the variable capacitance element;
a weighting circuit that performs weighting processing, based on the control bit signals, on an output potential of the second correction potential generation circuit; and
a combining circuit that combines an output voltage of the first correction potential generation circuit and an output voltage of the weighting circuit,the variable capacitance element of the voltage controlled oscillator circuit having capacitance thereof controlled by an output of the combining circuit of the temperature compensation block.
2 Assignments
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Accused Products
Abstract
A frequency synthesizer comprises a VCO group; a phase comparator; and a loop filter. Each VCO includes a varactor and a capacitor bank including a plurality of weighted capacitance elements, and a plurality of switches turned ON and OFF based on a control signal. Also provided a temperature compensation including a varactor correction potential generation circuit, a correction potential generation circuit for parasitic capacitance of the capacitor bank, a variable gain amplifier in which weighting processing, based on a control signal of the capacitor bank, is performed on an output potential of the correction potential generation circuit, and an adder circuit that adds the output voltage of the correction potential generation circuit of the varactor and output voltage of the variable gain amplifier, and the varactor of the VCO is controlled by output (correction potential) of the adder circuit.
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Citations
10 Claims
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1. A frequency synthesizer apparatus comprising:
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a voltage controlled oscillator circuit that varies oscillation frequency thereof by a control voltage supplied thereto, the voltage controlled oscillator circuit including; a variable capacitance element; and a capacitor bank that includes a plurality of weighted capacitance elements and a plurality of switches controlled turned ON and OFF based on a plurality of control bit signals corresponding to the plurality of capacitance elements, respectively; a phase comparator that performs phase comparison between an output signal fed back from the voltage controlled oscillator circuit and a reference signal supplied thereto, the output signal from the voltage controlled oscillator circuit being fed back directly or via a frequency divider to an input of the phase comparator; a loop filter that generates a control voltage for supply to the voltage controlled oscillator circuit, based on a result of the phase comparison; and a temperature compensation block that includes; a first correction potential generation circuit that generates a correction potential for parasitic capacitance of the capacitor bank of the voltage controlled oscillator circuit; a second correction potential generation circuit that generates a correction potential for the variable capacitance element; a weighting circuit that performs weighting processing, based on the control bit signals, on an output potential of the second correction potential generation circuit; and a combining circuit that combines an output voltage of the first correction potential generation circuit and an output voltage of the weighting circuit, the variable capacitance element of the voltage controlled oscillator circuit having capacitance thereof controlled by an output of the combining circuit of the temperature compensation block. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification