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US 10,256,791 B2Granted
Resonant circuit, filter circuit, and acoustic wave resonator
AssigneeTaiyo Yuden Co., Ltd.
InventorJun Tsutsumi
Life of this patent
Estimating the term…
Abstract
A resonant circuit includes: a capacitor of which a capacitance is variable; and an acoustic wave resonator to which the capacitor is connected in series and/or in parallel, a capacitance of the acoustic wave resonator being to be changed so that a change in input impedance and/or output impedance is reduced when the capacitance of the capacitor is changed.
Claims10
A resonant circuit comprising:
- an acoustic wave resonator;
- and
- at least one of a first capacitor connected in series to the acoustic wave resonator and a second capacitor connected in parallel to the acoustic wave resonator,
- wherein:
- a capacitance of the acoustic wave resonator is to be changed so that a change in input impedance and/or output impedance is reduced when a capacitance of said at least one of the first and second capacitors is changed, and
- an amount of change ΔC0 in the capacitance C0 of the acoustic wave resonator is given by (ΔCs×ΔCp−C02−ΔCp×C0)/(C0−ΔCs), when a capacitance of the first capacitor is changed from Cs to Cs+ΔCs, and a capacitance of the second capacitor is changed from Cp to Cp+ΔCp, where Cs and ΔCs are both zero when the first capacitor is not provided, and Cp and ΔCp are both zero when the second capacitor is not provided.
3 more elements
A filter circuit comprising:
- a plurality of series resonators connected in series between an input terminal and an output terminal;
- and
- one or more parallel resonators connected in parallel between the input terminal and the output terminal,
- wherein:
- at least one of the plurality of series resonators includes a resonant circuit that comprises:
- a capacitor of which a capacitance is variable;
- and
- an acoustic wave resonator to which the capacitor is connected in parallel, a capacitance of the acoustic wave resonator being to be changed so that a change in input impedance and/or output impedance is reduced when the capacitance of the capacitor is changed,
- a series resonator having a lowest antiresonant frequency among the plurality of series resonators includes the resonant circuit, and
- at least one of remaining series resonators of the plurality of series resonators does not include the resonant circuit.
7 more elements
A filter circuit comprising:
- one or more series resonators connected in series between an input terminal and an output terminal;
- and
- a plurality of parallel resonators connected in parallel between the input terminal and the output terminal,
- wherein:
- at least one of the plurality of parallel resonators includes a resonant circuit that comprises:
- a capacitor of which a capacitance is variable;
- and
- an acoustic wave resonator to which the capacitor is connected in series, a capacitance of the acoustic wave resonator being to be changed so that a change in input impedance and/or output impedance is reduced when the capacitance of the capacitor is changed,
- a parallel resonator having a highest resonant frequency among the plurality of parallel resonators includes the resonant circuit, and
- at least one of remaining parallel resonators of the plurality of parallel resonators does not include the resonant circuit.
7 more elements
An acoustic wave resonator comprising:
- a piezoelectric substrate;
- a pair of reflectors located on the piezoelectric substrate;
- and
- interdigital transducers that are located on the piezoelectric substrate between the pair of reflectors and electrically connected in parallel between a first terminal and a second terminal,
- wherein a switch is to be electrically connected in series between at least one interdigital transducer of the interdigital transducers and the first terminal and/or the second terminal,
- wherein the interdigital transducers include a first interdigital transducer to which the switch is not to be connected and a second interdigital transducer that is located between the first interdigital transducer and at least one of the pair of reflectors and to which the switch is to be connected, and
- wherein a number of pairs in the second interdigital transducer is less than a number of pairs in the first interdigital transducer.
4 more elements
Dependencies are inferred from the claim text.