Impedance matching circuit in transmitter circuit and control method thereof
First Claim
1. An impedance matching circuit in a transmitter circuit, comprising:
- a modulator for modulating an input signal to output a modulation signal;
a power amplifier for power-amplifying said modulation signal,an antenna for outputting the signal power-amplified by said power amplifier;
a demodulator for demodulating the signal power-amplified by said power amplifier to output a demodulation signal;
a band-outside-component detector for detecting a band-outside-component of said demodulation signal,a controller for outputting a control signal based upon the signal derived from said band-outside-component detector; and
an impedance matcher for matching an input impedance of said antenna with an impedance of said power amplifier by changing an impedance of said impedance matcher based upon said control signal.
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Accused Products
Abstract
In an impedance matching circuit used in a transmitter circuit, an occurrence of a reflection wave in an antenna is suppressed. The impedance matching circuit in a transmitter circuit includes a modulating circuit for modulating an input signal to output a modulation signal, a power amplifying circuit for power-amplifying the modulation signal, an antenna for outputting the signal power-amplified by the power amplifying circuit, a demodulating circuit for demodulating the signal power-amplified by the power amplifying circuit to output a demodulation signal, a band-outside-component detecting circuit for detecting a band-outside-component of the demodulation signal, a control circuit for outputting a control signal based upon the signal derived from the band-outside-component detecting circuit, and an impedance matching circuit for matching an input impedance of the antenna with an impedance of the power amplifying circuit by changing an impedance of the impedance matching circuit based upon the control signal.
52 Citations
20 Claims
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1. An impedance matching circuit in a transmitter circuit, comprising:
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a modulator for modulating an input signal to output a modulation signal; a power amplifier for power-amplifying said modulation signal, an antenna for outputting the signal power-amplified by said power amplifier; a demodulator for demodulating the signal power-amplified by said power amplifier to output a demodulation signal; a band-outside-component detector for detecting a band-outside-component of said demodulation signal, a controller for outputting a control signal based upon the signal derived from said band-outside-component detector; and an impedance matcher for matching an input impedance of said antenna with an impedance of said power amplifier by changing an impedance of said impedance matcher based upon said control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An impedance matching circuit in a transmitter circuit, comprising:
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a modulator for modulating an input signal to output a modulation signal; a power amplifier for power-amplifying said modulation signal; an antenna for outputting the signal power-amplified by said power amplifier; a demodulator for demodulating the signal power-amplified by said power amplifier to output a demodulation signal; a hand-outside-component detector for detecting a band-outside-component of said demodulation signal; a controller for outputting a control signal based upon the signal derived from said band-outside-component detector; and an impedance matcher for matching an input impedance of said antenna with an impedance of said power amplifier by changing an impedance of said impedance matcher based upon said control signal. wherein said controller compares a power output of the signal derived from said band-outside-component detector with a power value indicative of a predetermined threshold value signal, and outputs said control signal when the power value of the signal derived from said band-outside-component detector is larger than the power value indicative of said threshold value signal. - View Dependent Claims (10, 11)
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12. An impedance matching circuit comprising:
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a modulator for modulating an input signal to output a modulation signal; a power amplifier for power-amplifying said modulation signal; an antenna for outputting the signal power-amplified by said power amplifier; a demodulator for demodulating the signal power-amplified by said power amplifier to output a demodulation signal; a band-outside-component detector for detecting a band-outside-component of said demodulation signal; a controller for outputting a control signal based upon the signal derived from said band-outside-component detector; an impedance matcher for matching an input impedance of said antenna with an impedance of said power amplifier by changing an impedance of said impedance matcher based upon said control signal; and a threshold value signal generator for generating a threshold value signal by calculating a power value of the signal derived from said power amplifier, wherein said controller compares a power output of the signal derived from said band-outside-component detector with a power value indicative of a predetermined threshold value signal, and outputs said control signal when the power value of the signal derived from said band-outside-component detector is larger than the power value indicative of said threshold value signal. - View Dependent Claims (13)
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14. An impedance matching circuit in a transmitter unit, comprising:
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a modulator for modulating an input signal to output a modulation signal; a power amplifier for power-amplifying said modulation signal; an antenna for outputting the signal power-amplified by said power amplifier; a demodulator for demodulating the signal power-amplified by said power amplifier to output a demodulation signal; a band-outside-component detector for detecting a band-outside-component of said demodulation signal; a controller for outputting a control signal based upon the signal derived from said band-outside-component detector; and an impedance matcher for matching an input impedance of said antenna with an impedance of said power amplifier by changing an impedance of said impedance matcher based upon said control signal, wherein said demodulator includes; a signal detector for detecting a signal power-amplified by said power amplifier; and a frequency mixer for frequency-mixing the signal from said signal detector with a local signal employed when said modulator modulates said input signal, wherein said signal detector comprises a directional coupling circuit, and wherein said controller includes a peak hold circuit said peak hold circuit including; a first coil, one end of which is connected to said directional coupling circuit and the other end of which is connected to said antenna; a capacitor, one end of which is connected in parallel to the other end of said first coil; a second coil, one end of which is connected in series to said controller and the other end of which is connected in parallel to said capacitor; and a variable capacitance diode whose capacitance is varied by a voltage of said control signal by series-connecting an anode of said variable capacitance diode to said capacitor, and by connecting a cathode thereof to ground.
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15. An impedance matching method in a transmitter circuit, having a method for modulating an input signal by a modulating circuit, a method for power-amplifying the modulated signal by a power amplifying circuit, and a method for transmitting the power-amplified signal, comprising steps of:
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demodulating said power-amplified signal; detecting a band-outside-component of the demodulated signal; outputting a control signal based upon the detected band-outside-component; and matching an input impedance of said antenna with an impedance of said power amplifying circuit by changing an impedance based upon said control signal. - View Dependent Claims (16, 17)
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18. An impedance matching method in a transmitter circuit, having a method for modulating an input signal by a modulating circuit, a method for power-amplifying the modulated signal by a power amplifying circuit and a method for transmitting the power-amplified signal comprising steps of:
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demodulating said power-amplified signal; detecting a band-outside-component of the demodulated signal; outputting a control signal based upon the detected band-outside-component; and matching an input impedance of said antenna with an impedance of said power amplifying circuit by changing an impedance based upon said control signal, wherein said matching step includes steps of; comparing a power value of said detected band-outside-component with a power value indicative of a predetermined threshold value signal; and outputting said control signal when the power value of said detected band-outside-component is larger than the power value indicative of said threshold value signal in said comparing step.
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19. An impedance matching method in a transmitter circuit, having a method for modulating an input signal by a modulating circuit, a method for power-amplifying the modulated signal by a power amplifying circuit, and a method for transmitting the power-amplified signal, comprising steps of:
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demodulating said power-amplified signal; detecting a band-outside-component of the demodulated signal; outputting a control signal based upon the detected band-outside-component; matching an input impedance of said antenna with an impedance of said power amplifying circuit by changing an impedance based upon said control signal; generating a threshold value by calculating the power value of said power-amplified signal; comparing the power value of said detected band-outside-component with the power value indicative of said threshold value signal; and outputting said control signal when the power value of said detected band-output-component is larger than the power value indicative of said threshold value signal. - View Dependent Claims (20)
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Specification