System, circuit and method for tuning a resonant circuit
First Claim
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1. A circuit comprising:
- a source that provides an output at a drive frequency;
a resonant circuit having an input coupled to the source, an output, and first and second selectable resonant frequencies, the first resonant frequency being below the drive frequency and the second resonant frequency being above the drive frequency; and
a control coupled to the resonant circuit output that selects the first and second resonant frequencies to cause the resonant circuit to provide an output at an apparent resonant frequency equal to the drive frequency.
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Abstract
A circuit may be tuned to resonate at a driving frequency. The circuit includes a source that provides an output at a drive frequency and a resonant circuit having an input coupled to the source, an output, and first and second selectable resonant frequencies. The first resonant frequency is below the drive frequency and the second resonant frequency is above the drive frequency. A control coupled to the resonant circuit output selects the first and second resonant frequencies to cause the resonant circuit to provide an output at an apparent resonant frequency equal to the drive frequency.
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Citations
48 Claims
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1. A circuit comprising:
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a source that provides an output at a drive frequency;
a resonant circuit having an input coupled to the source, an output, and first and second selectable resonant frequencies, the first resonant frequency being below the drive frequency and the second resonant frequency being above the drive frequency; and
a control coupled to the resonant circuit output that selects the first and second resonant frequencies to cause the resonant circuit to provide an output at an apparent resonant frequency equal to the drive frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A resonant frequency control circuit comprising:
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a source that provides an output at a drive frequency;
a tunable resonant circuit having an input coupled to the source, an output, and a series resonant circuit between the input and output, the series resonant circuit including an inductance, a first capacitance in series with the inductance and a second capacitance selectably switchable in parallel with the first capacitance;
a sense circuit coupled to the output of the resonant circuit that senses a characteristic of the resonant circuit; and
a control circuit that switches the second capacitance in and out of parallel circuit with the first capacitance responsive to the characteristic of the resonant circuit to cause the resonant circuit to exhibit an apparent resonant frequency equal to the drive frequency. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A method comprising:
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driving a resonant circuit with a signal at a drive frequency to provide a resonant circuit response;
sensing a characteristic of the resonant circuit response; and
responsive to the characteristic, selectively varying the resonant frequency of the resonant circuit above and below the drive frequency to provide apparent resonance of the resonant circuit at the drive frequency. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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48. A system comprising:
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resonant circuit means for providing a variable resonant frequency;
means for driving the resonant circuit means with a signal at a drive frequency to cause a resonant circuit means response;
sensing means for sensing a characteristic of the resonant circuit means response; and
means responsive to the characteristic for selectively varying the resonant frequency of the resonant circuit means above and below the drive frequency for providing apparent resonance of the resonant circuit means at the drive frequency.
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Specification