# US 2020/0403604 A1 · Multiplexer, high-frequency front-end circuit, and communication device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0403604 A1 - Document ID: US20200403604A1 - Status: Published application - Kind: A1 - Application number: 17/009,933 - Filed: 2020-09-02 - Published: 2020-12-24 - Earliest claimed: 2018-03-08 - Assignees: Murata Manufacturing Co., Ltd. - Applicants: Murata Manufacturing Co., Ltd. - Inventors: Masakazu TANI - Web page: https://patentgrep.com/patent/US20200403604A1 ## CPC - H03H 9/72: Networks using surface acoustic waves - H03H 9/725: {Duplexers} - H03F 3/19: with semiconductor devices only - H03F 3/195: in integrated circuits - H03F 3/245: {with semiconductor devices only} - H03F 3/72: Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal - H03H 9/02559: {of lithium niobate or lithium-tantalate substrates} - H03H 9/145: for networks using surface acoustic waves - H03H 9/25: Constructional features of resonators using surface acoustic waves {(devices for manipulating acoustic surface waves in general G10K11/36)} - H03H 9/64: using surface acoustic waves - H03H 9/6436: {having one acoustic track only} - H04B 1/0057: {using diplexing or multiplexing filters for selecting the desired band} - H04B 1/52: Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa - H04B 1/58: Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa - H03F 2200/111: the amplifier being a dual or triple band amplifier, e.g. 900 and 1800 MHz, e.g. switched or not switched, simultaneously or not - H03F 2200/451: the amplifier being a radio frequency amplifier - H03F 2203/7209: the gated amplifier being switched from a first band to a second band - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) - H03F: AMPLIFIERS - H04B: TRANSMISSION ## Abstract Filters 10 and 20 having respective pass bands different from each other, a common terminal to which a terminal 11 of the filter 10 and a terminal of the filter 20 are connected, and an inductor of which one end is connected to the terminal 11 and another end is connected to the common terminal. The filter 10 includes a longitudinally coupled resonator formed of a resonator 132 and resonators 131 and 133 disposed on both sides of the resonator 132, in which the resonator 132 is connected to the terminal 11, and a parallel resonator of which one end is connected to the resonator 132 and another end is connected to a ground electrode, and the resonator 132 and the parallel resonator of the resonators included in the filter 10 are connected to a signal path between the resonator 132 and the terminal 11. ## Claims ### Claim 1 A multiplexer, comprising: a first filter having a first pass band, and a second filter having a second pass band, the second pass band being different than the first pass band; a common terminal to which a first terminal of the first filter and a second terminal of the second filter are connected; and an inductor having a first end that is connected to the first terminal and a second end that is connected to the common terminal, wherein: the first filter comprises: a longitudinally coupled resonator circuit comprising one or more first resonators and a plurality of second resonators, each side of each of the one or more first resonators being connected to one of the plurality of second resonators, and the one or more first resonators being connected to the first terminal, and a third resonator having a first end that is connected to the one or more first resonators and a second end that is connected to a ground electrode, and the one or more first resonators and the third resonator are connected to a signal path between the longitudinally coupled resonator circuit and the first terminal. ### Claim 2 (depends on 1) The multiplexer according to claim 1, wherein an anti-resonant frequency of the third resonator is within the first pass band of the first filter. ### Claim 3 A multiplexer, comprising: a first filter having a first pass band and a second filter having a second pass band, the second pass band being different than the first pass band; a common terminal to which a first terminal of the first filter and a second terminal of the second filter are connected; and an inductor having a first end that is connected to the first terminal and a second end that is connected to the common terminal, wherein: the first filter comprises: a longitudinally coupled resonator circuit comprising of one or more first resonators and a plurality of second resonators, each side of each of the one or more first resonators being connected to one of the plurality of second resonators, and the plurality of second resonators being connected to the first terminal, and the plurality of second resonators are connected to a signal path between the longitudinally coupled resonator and the first terminal. ### Claim 4 (depends on 1) The multiplexer according to claim 1, further comprising: a first capacitor having a first end that is connected to a signal path between the longitudinally coupled resonator circuit and the inductor, and a second end that is connected to the ground electrode. ### Claim 5 (depends on 3) The multiplexer according to claim 3, further comprising: a first capacitor having a first end that is connected to a signal path between the longitudinally coupled resonator circuit and the inductor, and a second end that is connected to the ground electrode. ### Claim 6 (depends on 4) The multiplexer according to claim 4, wherein the first capacitor is incorporated in the first filter. ### Claim 7 (depends on 5) The multiplexer according to claim 5, wherein the first capacitor is incorporated in the first filter. ### Claim 8 (depends on 1) The multiplexer according to claim 1, further comprising: a second capacitor having a first end that is connected to the second terminal, and a second end that is connected to the common terminal. ### Claim 9 (depends on 3) The multiplexer according to claim 3, further comprising: a second capacitor having a first end that is connected to the second terminal, and a second end that is connected to the common terminal. ### Claim 10 (depends on 1) The multiplexer according to claim 1, wherein: the first filter is on a piezoelectric substrate, and the piezoelectric substrate comprises: a piezoelectric film on a first surface of the piezoelectric substrate, the first surface comprising an interdigital transducer (IDT) electrode thereon, a high acoustic velocity support substrate configured to propagate a bulk wave at a greater acoustic velocity than the piezoelectric film, and a low acoustic velocity film between the high acoustic velocity support substrate and the piezoelectric film, the low acoustic velocity film being configured to propagate a bulk wave at a lower acoustic velocity than the piezoelectric film. ### Claim 11 (depends on 3) The multiplexer according to claim 3, wherein: the first filter is on a piezoelectric substrate, and the piezoelectric substrate comprises: a piezoelectric film on a first surface, the first surface comprising an interdigital transducer (IDT) electrode thereon, a high acoustic velocity support substrate configured to propagate a bulk wave at a greater acoustic velocity than the piezoelectric film, and a low acoustic velocity film between the high acoustic velocity support substrate and the piezoelectric film, the low acoustic velocity film being configured to propagate a bulk wave at a lower acoustic velocity than the piezoelectric film. ### Claim 12 (depends on 1) The multiplexer according to claim 1, wherein the first filter comprises: a piezoelectric single crystal substrate of lithium niobate (LiNbO3), an interdigital transducer (IDT) electrode on the piezoelectric single crystal substrate, and a dielectric film on the piezoelectric single crystal substrate and the IDT electrode. ### Claim 13 (depends on 3) The multiplexer according to claim 3, wherein the first filter comprises: a piezoelectric single crystal substrate of lithium niobate (LiNbO3), an interdigital transducer (IDT) electrode on the piezoelectric single crystal substrate, and a dielectric film on the piezoelectric single crystal substrate and the IDT electrode. ### Claim 14 (depends on 1) A high-frequency front-end circuit, comprising: the multiplexer according to claim 1; and an amplifier circuit connected to the multiplexer. ### Claim 15 (depends on 3) A high-frequency front-end circuit, comprising: the multiplexer according to claim 3; and an amplifier circuit connected to the multiplexer. ### Claim 16 (depends on 14) A communication device, comprising: a radio frequency (RF) signal processing circuit configured to process a high-frequency signal transmitted and received by an antenna; and the high-frequency front-end circuit according to claim 14 configured to transmit the high-frequency signal between the antenna and the RF signal processing circuit. ### Claim 17 (depends on 15) A communication device, comprising: a radio frequency (RF) signal processing circuit configured to process a high-frequency signal transmitted and received by an antenna; and the high-frequency front-end circuit according to claim 15 configured to transmit the high-frequency signal between the antenna and the RF signal processing circuit.