# US 2020/0403601 A1 · Acoustic wave resonator with transverse spurious mode for filter steepness > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0403601 A1 - Document ID: US20200403601A1 - Status: Published application - Kind: A1 - Application number: 16/900,175 - Filed: 2020-06-12 - Published: 2020-12-24 - Earliest claimed: 2019-06-19 - Assignees: Skyworks Solutions, Inc. - Applicants: Skyworks Solutions, Inc. - Inventors: Tomoya Komatsu; Yiliu Wang; Akira Ochiai; Joshua James Caron - Web page: https://patentgrep.com/patent/US20200403601A1 ## CPC - H03H 9/6483: {Ladder SAW filters} - H03H 9/02834: {of temperature influence (cut angles H03H9/02543)} - H03H 9/25: Constructional features of resonators using surface acoustic waves {(devices for manipulating acoustic surface waves in general G10K11/36)} - H03H 9/6406: {Filters characterised by a particular frequency characteristic} - H03H 9/725: {Duplexers} - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) ## Abstract Aspects of this disclosure relate to an acoustic wave filter with an acoustic wave resonator arranged to concentrate a transverse spurious mode at a frequency. Such an acoustic wave resonator can have a narrow aperture to concentrate the transverse spurious mode. The transverse spurious mode can increase steepness of a skirt of the acoustic wave filter. Related methods, acoustic wave devices, multiplexers, radio frequency front ends, radio frequency modules, and wireless communication devices are disclosed. ## Claims ### Claim 1 An acoustic wave filter with a transverse spurious mode for increasing filter skirt steepness, the acoustic wave filter comprising: a plurality of series acoustic wave resonators including a first series acoustic wave resonator, the first series acoustic wave resonator configured to concentrate a transverse spurious mode at a frequency; and a plurality of shunt acoustic wave resonators, the plurality of series acoustic wave resonators and the plurality of shunt acoustic wave resonators together arranged to filter a radio frequency signal, and the transverse spurious mode of the first series acoustic wave resonator configured to increase steepness of a skirt of the acoustic wave filter. ### Claim 2 (depends on 1) The acoustic wave filter of claim 1 wherein the first series acoustic wave resonator includes an interdigital transducer electrode and is configured to generate an acoustic wave having a wavelength of λ, the interdigital transducer electrode having an aperture of less than 10λ. ### Claim 3 (depends on 2) The acoustic wave filter of claim 2 wherein the aperture is less than 7λ. ### Claim 4 (depends on 2) The acoustic wave filter of claim 2 wherein the aperture is at least 1λ. ### Claim 5 (depends on 2) The acoustic wave filter of claim 2 wherein the plurality of series acoustic wave resonators includes additional series acoustic wave resonators having respective interdigital transducer electrodes having apertures of less than 10λ. ### Claim 6 (depends on 2) The acoustic wave filter of claim 2 wherein the plurality of shunt acoustic wave resonators each include an interdigital transducer electrode having an aperture of at least 15λ and no greater than 30λ. ### Claim 7 (depends on 1) The acoustic wave filter of claim 1 wherein the first series acoustic wave resonator does not include a piston mode structure. ### Claim 8 (depends on 1) The acoustic wave filter of claim 1 wherein the plurality of shunt acoustic wave resonators each include an interdigital transducer electrode having an aperture that is greater than an aperture of an interdigital transducer electrode of the first series acoustic wave resonator. ### Claim 9 (depends on 1) The acoustic wave filter of claim 1 wherein the frequency is above a resonant frequency of the first series acoustic wave resonator, and the skirt of the acoustic wave filter is above a pass band of the acoustic wave filter. ### Claim 10 (depends on 1) The acoustic wave filter of claim 1 wherein the first series acoustic wave resonator is a temperature compensated surface acoustic wave resonator. ### Claim 11 An acoustic wave filter with a transverse spurious mode for increasing skirt steepness, the acoustic wave filter comprising: a plurality of shunt acoustic wave resonators including a first shunt acoustic wave resonator, the first shunt acoustic wave resonator configured to concentrate a transverse spurious mode at a frequency; and a plurality of series acoustic wave resonators, the plurality of shunt acoustic wave resonators and the plurality of series acoustic wave resonators together arranged to filter a radio frequency signal, and the transverse spurious mode of the first shunt acoustic wave resonator configured to increase skirt steepness of the acoustic wave filter. ### Claim 12 (depends on 11) The acoustic wave filter of claim 11 wherein the first shunt acoustic wave resonator includes an interdigital transducer electrode and is configured to generate an acoustic wave having a wavelength of λ, and the interdigital transducer electrode has an aperture of less than 10λ. ### Claim 13 (depends on 12) The acoustic wave filter of claim 12 wherein the aperture is at least 1λ. ### Claim 14 (depends on 11) The acoustic wave filter of claim 11 wherein the first shunt acoustic wave resonator is a temperature compensated surface acoustic wave resonator without a piston mode structure. ### Claim 15 An acoustic wave filter with a transverse spurious mode for increasing skirt steepness, the acoustic wave filter comprising a plurality of acoustic wave resonators configured to filter a radio frequency signal, the plurality of acoustic wave resonators including a first acoustic wave resonator that includes an interdigital transducer electrode and configured to generate an acoustic wave having a wavelength of λ, the interdigital transducer electrode having an aperture of less than 10λ to concentrate a transverse spurious mode at a frequency, and the transverse spurious mode of the first acoustic wave resonator configured to increase steepness of a skirt of the acoustic wave filter. ### Claim 16 (depends on 15) The acoustic wave filter of claim 15 wherein the plurality of acoustic wave resonators include a plurality of series acoustic wave resonators and a plurality of shunt acoustic wave resonators, and the plurality of series acoustic wave resonators include the first acoustic wave resonator. ### Claim 17 (depends on 16) The acoustic wave filter of claim 16 wherein the plurality of shunt acoustic wave resonators each include an interdigital transducer electrode having an aperture that is greater than the aperture of the interdigital transducer electrode of the first series acoustic wave resonator. ### Claim 18 (depends on 15) The acoustic wave filter of claim 15 wherein the plurality of acoustic wave resonators include a plurality of series acoustic wave resonators and a plurality of shunt acoustic wave resonators, and the plurality of shunt acoustic wave resonators include the first acoustic wave resonator. ### Claim 19 (depends on 15) The acoustic wave filter of claim 15 wherein the aperture is at least 1λ. ### Claim 20 (depends on 15) The acoustic wave filter of claim 15 wherein the frequency is above a resonant frequency of the first acoustic wave resonator, and the skirt of the acoustic wave filter is above the cutoff frequency of an upper edge of a passband of the acoustic wave filter.