# US 12,003,263 B2 · Radio frequency front end with tunable filters > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,003,263 B2 - Document ID: US12003263B2 - Status: Granted - Kind: B2 - Application number: 17/410,902 - Filed: 2021-08-24 - Published: 2022-03-03 - Granted: 2024-06-04 - Earliest claimed: 2020-08-31 - Assignees: Skyworks Solutions, Inc. - Applicants: Skyworks Solutions, Inc. - Inventors: Fei Jia; Joshua Kawika Ellis; Kun Chen; Shayan Farahvash; Haisu Ju; Haibo Cao - Web page: https://patentgrep.com/patent/US12003263B2 ## CPC - H04B 1/1036: {with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters (H04B1/123 takes precedence; filter circuits H03H)} - H03F 1/565: {using inductive elements} - H03F 3/19: with semiconductor devices only - H03F 3/245: {with semiconductor devices only} - H03H 7/0115: {comprising only inductors and capacitors (H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence)} - H03H 7/0153: {Electrical filters; Controlling thereof} - H03H 7/09: Filters comprising mutual inductance - H03H 7/1758: {Series LC in shunt or branch path (H03H7/1791 takes precedence)} - H03H 7/1766: {Parallel LC in series path (H03H7/1783 takes precedence)} - H04M 1/0202: {Portable telephone sets, e.g. cordless phones, mobile phones or bar type handsets (constructional features of telephone transmitters or receivers, e.g. of speakers or microphones H04M1/03)} - 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 2200/171: A filter circuit coupled to the output of an amplifier - H03F 2200/451: the amplifier being a radio frequency amplifier - H03H 2210/025: Capacitor - H03H 2210/033: Continuous - H03H 2210/036: Stepwise - H04B 2001/1063: {using a notch filter} - H04B 2001/1072: {by tuning the receiver frequency} - H04B: TRANSMISSION - H03F: AMPLIFIERS - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) - H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08) ## Abstract Aspects of this disclosure relate to a radio frequency system with tunable notch filtering. The radio frequency system includes a first tunable filter and a second tunable filter. The first tunable filter is coupled between an output of a power amplifier and a radio frequency switch. The second tunable filter is coupled between an antenna switch and an antenna node. The second tunable filter has a notch at a lower frequency than a notch of the first tunable filter. Related methods and wireless communication devices are also disclosed. ## Claims ### Claim 1 A radio frequency system with tunable notch filtering, the radio frequency system comprising: a power amplifier having an output; a multi-throw switch; a first tunable filter coupled between the output of the power amplifier and the multi-throw switch, the first tunable filter having at least a first tunable notch; an antenna switch coupled to the multi-throw switch by way of one or more radio frequency signal paths; and a second tunable filter coupled between the antenna switch and an antenna node, the second tunable filter having at least a second tunable notch, the second tunable notch being at a lower frequency than the first tunable notch, the second tunable filter being an L network that includes a parallel inductor-capacitor circuit and a shunt series inductor-capacitor circuit, and the parallel inductor-capacitor circuit arranged in series between the antenna switch and the antenna node. ### Claim 2 (depends on 1) The radio frequency system of claim 1 wherein the second tunable notch corresponds to a higher order harmonic than the first tunable notch. ### Claim 3 (depends on 1) The radio frequency system of claim 1 wherein the first tunable filter has a plurality of tunable notches, the plurality of tunable notches including the first tunable notch. ### Claim 4 (depends on 3) The radio frequency system of claim 3 wherein the plurality of tunable notches each correspond to a higher respective frequency than the second tunable notch. ### Claim 5 (depends on 3) The radio frequency system of claim 3 wherein the second tunable filter has a single tunable notch, the single tunable notch being the second tunable notch. ### Claim 6 (depends on 3) The radio frequency system of claim 3 wherein the second tunable filter has a second plurality of tunable notches, the second plurality of tunable notches including the second tunable notch. ### Claim 7 (depends on 1) The radio frequency system of claim 1 wherein the parallel inductor-capacitor circuit includes a tunable capacitance circuit. ### Claim 8 (depends on 7) The radio frequency system of claim 7 wherein the shunt series inductor-capacitor circuit includes a second tunable capacitance circuit. ### Claim 9 (depends on 1) The radio frequency system of claim 1 wherein the one or more radio frequency signal paths includes a first radio frequency signal path, and the first radio frequency signal path includes a band pass filter. ### Claim 10 A radio frequency system with tunable notch filtering, the radio frequency system comprising: a power amplifier having an output; a multi-throw switch; a first tunable filter coupled between the output of the power amplifier and the multi-throw switch, the first tunable filter having at least a first tunable notch; an antenna switch coupled to the multi-throw switch by way of one or more radio frequency signal paths; and a second tunable filter coupled between the antenna switch and an antenna node, the second tunable filter having at least a second tunable notch, the second tunable notch being at a lower frequency than the first tunable notch, the second tunable filter including a first inductor, a second inductor mutually coupled to the first inductor, and a tunable capacitance circuit coupled to the first inductor. ### Claim 11 (depends on 10) The radio frequency system of claim 10 wherein the first tunable filter includes a third inductor, a fourth inductor mutually coupled to the third inductor, and a second tunable capacitance circuit coupled to the third inductor. ### Claim 12 (depends on 10) The radio frequency system of claim 10 wherein the second tunable filter is an L network. ### Claim 13 (depends on 12) The radio frequency system of claim 12 wherein the L network includes a parallel inductor-capacitor circuit and a shunt series inductor-capacitor circuit, the parallel inductor-capacitor circuit arranged in series between the antenna switch and the antenna node. ### Claim 14 (depends on 10) The radio frequency system of claim 10 further comprising a tunable shunt capacitance circuit coupled to a node between the first tunable filter and the multi-throw switch, the tunable shunt capacitance circuit being configured to tune a load line. ### Claim 15 A radio frequency system with tunable notch filtering, the radio frequency system comprising: a power amplifier having an output; a multi-throw switch; a first tunable filter coupled between the output of the power amplifier and the multi-throw switch, the first tunable filter having at least a first tunable notch, the first tunable filter including a first inductor, a second inductor mutually coupled to the first inductor, and a tunable capacitance circuit coupled to the first inductor; an antenna switch coupled to the multi-throw switch by way of one or more radio frequency signal paths, and a second tunable filter coupled between the antenna switch and an antenna node, the second tunable filter having at least a second tunable notch, the second tunable notch being at a lower frequency than the first tunable notch. ### Claim 16 (depends on 15) The radio frequency system of claim 15 further comprising a tunable shunt capacitance circuit coupled to a node between the first tunable filter and the multi-throw switch, the tunable shunt capacitance circuit being configured to tune a load line. ### Claim 17 (depends on 15) The radio frequency system of claim 15 wherein the second tunable filter is an L network that includes a parallel inductor-capacitor circuit and a shunt series inductor-capacitor circuit, the parallel inductor-capacitor circuit arranged in series between the antenna switch and the antenna node. ### Claim 18 A radio frequency system with tunable notch filtering, the radio frequency system comprising: a power amplifier having an output; a multi-throw switch; a first tunable filter coupled between the output of the power amplifier and the multi-throw switch, the first tunable filter having at least a first tunable notch; a tunable shunt capacitance circuit coupled to a node between the first tunable filter and the multi-throw switch, the tunable shunt capacitance circuit being configured to tune a load line; an antenna switch coupled to the multi-throw switch by way of one or more radio frequency signal paths; and a second tunable filter coupled between the antenna switch and an antenna node, the second tunable filter having at least a second tunable notch, the second tunable notch being at a lower frequency than the first tunable notch. ### Claim 19 (depends on 18) The radio frequency system of claim 18 wherein the second tunable filter is an L network that includes a parallel inductor-capacitor circuit and a shunt series inductor-capacitor circuit, the parallel inductor-capacitor circuit arranged in series between the antenna switch and the antenna node. ### Claim 20 (depends on 18) The radio frequency system of claim 18 wherein the second tunable notch corresponds to a higher order harmonic than the first tunable notch.