# US 2014/0197903 A1 · Signal separation device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197903 A1 - Document ID: US20140197903A1 - Status: Published application - Kind: A1 - Application number: 14/217,924 - Filed: 2014-03-18 - Published: 2014-07-17 - Earliest claimed: 2011-09-30 - Assignees: Murata Manufacturing Co., Ltd. - Applicants: Murata Manufacturing Co., Ltd. - Inventors: Kenichi UESAKA - Web page: https://patentgrep.com/patent/US20140197903A1 ## CPC - H03H 9/725: {Duplexers} - H03H 9/02535: {of surface acoustic wave devices} - H03H 9/64: using surface acoustic waves - H03H 9/706: {Duplexers} - H03H 9/0542: {consisting of a lateral arrangement (H03H9/0566 takes precedence)} - H03H 9/0576: {including surface acoustic wave [SAW] devices} - H03H 9/059: {consisting of mounting pads or bumps} - H03H 9/6483: {Ladder SAW filters} - H10W 74/00: Encapsulations, e.g. protective coatings - H10W 90/724: {between a chip and a stacked insulating package substrate, interposer or RDL} - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract A signal separation device is a duplexer in which a reception frequency band is located at higher frequencies than a transmission frequency band. A series arm of a ladder transmission filter includes a plurality of series arm resonators, and parallel arms respectively include parallel arm resonators. The parallel arm resonators include the parallel arm resonators having resonant frequencies lower than those of the series arm resonators and the parallel arm resonator that has a resonant frequency which is located within the reception frequency band and which is higher than the resonant frequency of the series arm resonators and that has a lower capacitance than the series arm resonators and the parallel arm resonators. ## Claims ### Claim 1 (canceled) ### Claim 2 A signal separation device including a first passband and a second passband that is located at higher frequencies than the first passband and that is adjacent to the first passband, the device comprising: a common terminal; a first terminal; a second terminal; a first filter unit that is electrically connected between the common terminal and the first terminal and that defines at least the first passband; and a second filter unit that is electrically connected between the common terminal and the second terminal and that defines at least the second passband; wherein the first filter unit is a ladder filter including: a series arm electrically connected between the common terminal and the first terminal; and a plurality of parallel arms electrically connected between the series arm and a ground potential; wherein the series arm includes at least one series arm resonator; the plurality of parallel arms each include at least one parallel arm resonator; and the parallel arm resonators include at least one first resonator that has a lower resonant frequency than the series arm resonator and a second resonator that has a resonant frequency which is located within the second passband and which is higher than the resonant frequency of the series arm resonator and that has a lower capacitance than the series arm resonator and the first resonator. ### Claim 3 (depends on 2) The signal separation device according to claim 2, wherein at least one of the at least one series arm resonator is electrically connected between the second resonator and the common terminal. ### Claim 4 (depends on 2) The signal separation device according to claim 2, wherein at least one of the at least one first resonator is electrically connected between the second resonator and the common terminal. ### Claim 5 (depends on 2) The signal separation device according to claim 2, wherein the second resonator has a smaller ratio of an impedance at an anti-resonant point to an impedance at a resonant point than the first resonator. ### Claim 6 (depends on 5) The signal separation device according to claim 5, wherein the first resonator is a surface acoustic wave resonator including a first reflector; the second resonator is a surface acoustic wave resonator including a second reflector; and the second reflector has a smaller number of electrode fingers than the first reflector. ### Claim 7 (depends on 5) The signal separation device according to claim 5, wherein the first resonator is a surface acoustic wave resonator including first comb-shaped electrodes; the second resonator is a surface acoustic wave resonator including second comb-shaped electrodes; and the second comb-shaped electrodes have a smaller intersecting width than the first comb-shaped electrodes. ### Claim 8 (depends on 2) The signal separation device according to claim 2, wherein the second resonator includes a plurality of resonators electrically connected in series. ### Claim 9 (depends on 2) The signal separation device according to claim 2, wherein the first passband and the second passband are adjacent to each other with a range of about 20 MHz therebetween. ### Claim 10 (depends on 2) The signal separation device according to claim 2, wherein the signal separation device is one of a duplexer and a triplexer. ### Claim 11 (depends on 2) The signal separation device according to claim 2, wherein each of the first filter unit and the second filter unit is a surface acoustic wave filter chip. ### Claim 12 (depends on 2) The signal separation device according to claim 2, wherein the signal separation device is duplexer defined by one of a chip size package surface acoustic wave filter device and a wafer level package surface acoustic wave filter device. ### Claim 13 (depends on 2) The signal separation device according to claim 2, wherein both of the first filter unit and the second filter unit are defined by a single surface acoustic wave filter chip. ### Claim 14 (depends on 2) The signal separation device according to claim 2, wherein one of the parallel arms includes at least two resonators connected in series. ### Claim 15 (depends on 2) The signal separation device according to claim 2, wherein the series arm resonators and one of the parallel arm resonators are provided between another of the parallel arm resonators and an antenna terminal. ### Claim 16 (depends on 2) A communication device comprising the signal separation device according to claim 2. ### Claim 17 (depends on 16) The communication device according to claim 16, wherein the communication device is a cellular phone.