# US 11,121,683 B2 · Radio-frequency 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 11,121,683 B2 - Document ID: US11121683B2 - Status: Granted - Kind: B2 - Application number: 16/747,636 - Filed: 2020-01-21 - Published: 2020-05-14 - Granted: 2021-09-14 - Earliest claimed: 2017-07-25 - Assignees: Murata Manufacturing Co., Ltd. - Applicants: Murata Manufacturing Co., Ltd. - Inventors: Takahisa Toyomura - Web page: https://patentgrep.com/patent/US11121683B2 ## CPC - H03F 3/245: {with semiconductor devices only} - H03F 1/52: Circuit arrangements for protecting such amplifiers {(monitoring arrangements G01R31/28; increasing reliability in communication systems, e.g. using redundancy H04B1/74)} - H03F 3/19: with semiconductor devices only - H03F 3/24: of transmitter output stages - H03F 3/68: Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics {(power amplifiers using a combination of several semiconductor amplifiers H03F3/211; combinations of amplifiers using coupling networks with distributed constants H03F3/602)} - H03F 3/72: Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal - H03G 3/3042: {in modulators, frequency-changers, transmitters or power amplifiers} - H04B 1/04: Circuits - H03F 3/195: in integrated circuits - H03F 2200/451: the amplifier being a radio frequency amplifier - H04B 1/50: using different frequencies for the two directions of communication - H03F: AMPLIFIERS - H03G: CONTROL OF AMPLIFICATION - H04B: TRANSMISSION ## Abstract A radio-frequency circuit includes a power amplifier circuit, a first switch, a duplexer, a second switch, a capacitor element, and a controller. The first switch includes a first common terminal and first selection terminals. An output signal of the power amplifier circuit is applied to the first common terminal. The duplexer is a filter connected at one terminal to the first selection terminal. The second switch includes a second common terminal and plural second selection terminals. The plural second selection terminals includes the second selection terminal connected to the other terminal of the duplexer. The capacitor element is built in the first switch. The controller controls the gain of the power amplifier circuit in accordance with a monitor signal obtained via the capacitor element so as to regulate the maximum output level of the power amplifier circuit. ## Claims ### Claim 1 A radio-frequency circuit comprising: a power amplifier circuit; a first switch having a first common terminal, a first selection terminal, and a monitor terminal, the first common terminal being connected to the power amplifier circuit and being selectively connected to the first selection terminal; a filter having first and second terminals, the first terminal being connected to the first selection terminal; a second switch having a second selection terminal and a second common terminal, the second selection terminal being connected to the second terminal of the filter, and the second common terminal being selectively connected to the second selection terminal; a capacitive element in the first switch, the capacitive element being connected to the monitor terminal; and a controller connected to the monitor terminal. ### Claim 2 (depends on 1) The radio-frequency circuit according to claim 1, wherein the controller is configured to control a gain of the power amplifier circuit in accordance with a monitor signal obtained from the monitor terminal in a manner that maximizes an output level of the power amplifier circuit. ### Claim 3 (depends on 1) The radio-frequency circuit according to claim 1, wherein the capacitive element is connected to the first common terminal. ### Claim 4 (depends on 2) The radio-frequency circuit according to claim 2, wherein the capacitive element is connected to the first common terminal. ### Claim 5 (depends on 1) The radio-frequency circuit according to claim 1, wherein the capacitive element is connected to the first selection terminal. ### Claim 6 (depends on 2) The radio-frequency circuit according to claim 2, wherein the capacitive element is connected to the first selection terminal. ### Claim 7 (depends on 5) The radio-frequency circuit according to claim 5, wherein: the first switch further has a third selection terminal and a second monitor terminal, the first common terminal being selectively connected to the third selection terminal, the controller is further connected to the second monitor terminal, and the radio-frequency circuit further comprises a second capacitive element in the first switch, the second capacitive element being connected to the third selection terminal and to the second monitor terminal. ### Claim 8 (depends on 6) The radio-frequency circuit according to claim 6, wherein: the first switch further has a third selection terminal and a second monitor terminal, the first common terminal being selectively connected to the third selection terminal, the controller is further connected to the second monitor terminal, and the radio-frequency circuit further comprises a second capacitive element in the first switch, the second capacitive element being connected to the third selection terminal and to the second monitor terminal. ### Claim 9 A radio-frequency circuit comprising: a first power amplifier circuit and a second power amplifier circuit; a first switch having a first common terminal, a third common terminal, a first selection terminal, a first monitor terminal, and a second monitor terminal, the first common terminal being connected to the first power amplifier circuit and being selectively connected to the first selection terminal, and the third common terminal being connected to the second power amplifier circuit; a filter having first and second terminals, the first terminal being connected to the first selection terminal; a second switch having a second selection terminal and a second common terminal, the second selection terminal being connected to the second terminal of the filter, the second common terminal being selectively connected to the second selection terminal; a first capacitive element in the first switch, the first capacitive element being connected to the first common terminal and to the first monitor terminal; a second capacitive element in the first switch, the first capacitive element being connected to the third common terminal and to the second monitor terminal; and a controller connected to the first monitor terminal and to the second monitor terminal. ### Claim 10 (depends on 1) A communication device comprising: the radio-frequency circuit according to claim 1; and an RF signal processing circuit connected to the radio-frequency circuit. ### Claim 11 (depends on 2) A communication device comprising: the radio-frequency circuit according to claim 2; and an RF signal processing circuit connected to the radio-frequency circuit. ### Claim 12 (depends on 3) A communication device comprising: the radio-frequency circuit according to claim 3; and an RF signal processing circuit connected to the radio-frequency circuit. ### Claim 13 (depends on 5) A communication device comprising: the radio-frequency circuit according to claim 5; and an RF signal processing circuit connected to the radio-frequency circuit. ### Claim 14 (depends on 7) A communication device comprising: the radio-frequency circuit according to claim 7; and an RF signal processing circuit connected to the radio-frequency circuit. ### Claim 15 (depends on 9) A communication device comprising: the radio-frequency circuit according to claim 9; and an RF signal processing circuit connected to the radio-frequency circuit.