# US 2019/0356281 A1 · Power amplifier > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0356281 A1 - Document ID: US20190356281A1 - Status: Published application - Kind: A1 - Application number: 16/407,498 - Filed: 2019-05-09 - Published: 2019-11-21 - Earliest claimed: 2018-05-15 - Assignees: Murata Manufacturing Co., Ltd. - Applicants: Murata Manufacturing Co., Ltd. - Inventors: Yuri HONDA; Fumio HARIMA; Kenji MUKAI - Web page: https://patentgrep.com/patent/US20190356281A1 ## CPC - H03F 1/565: {using inductive elements} - H03F 1/22: by use of cascode coupling, i.e. earthed cathode or emitter stage followed by earthed grid or base stage respectively - H03F 1/26: Modifications of amplifiers to reduce influence of noise generated by amplifying elements - H03F 1/30: Modifications of amplifiers to reduce influence of variations of temperature or supply voltage {or other physical parameters (in differential amplifiers H03F3/45479)} - H03F 1/56: Modifications of input or output impedances, not otherwise provided for - H03F 3/19: with semiconductor devices only - H03F 3/21: with semiconductor devices only {(H03F3/245 takes precedence)} - H03F 3/245: {with semiconductor devices only} - H03F 2200/222: A circuit being added at the input of an amplifier to adapt the input impedance of the amplifier - H03F 2200/318: A matching circuit being used as coupling element between two amplifying stages - H03F 2200/387: A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier - H03F 2200/408: the output amplifying stage of an amplifier comprising three power stages - H03F 2200/451: the amplifier being a radio frequency amplifier - H03F: AMPLIFIERS ## Abstract A power amplifier includes power amplification circuits in a plurality of stages including a first stage and a second stage, each power amplification circuit including a transistor. The power amplification circuit in the first stage includes a first impedance circuit between an emitter of the transistor and a reference potential. The first impedance circuit has an impedance that does not vary with frequency or an impedance that varies with frequency. The power amplification circuit in the second stage includes a second impedance circuit between an emitter of the transistor and a reference potential. The second impedance circuit has an impedance that does not vary with frequency or an impedance that varies with frequency. ## Claims ### Claim 1 A power amplifier for amplifying a radio-frequency signal, comprising: a first stage power amplification circuit comprising: a first transistor, and a first impedance circuit between an emitter of the first transistor and a reference potential; and a second stage power amplification circuit comprising: a second transistor, and a second impedance circuit between an emitter of the second transistor and the reference potential. ### Claim 2 (depends on 1) The power amplifier according to claim 1, wherein the first impedance circuit or the second impedance circuit comprises a resistor, an inductor, or a tank circuit. ### Claim 3 (depends on 1) The power amplifier according to claim 1, wherein the first stage power amplification circuit precedes the second stage power amplification circuit, and an impedance of the first impedance circuit is greater than an impedance of the second impedance circuit within a frequency range of the radio-frequency signal. ### Claim 4 (depends on 2) The power amplifier according to claim 2, wherein the first stage power amplification circuit precedes the second stage power amplification circuit, and an impedance of the first impedance circuit is greater than an impedance of the second impedance circuit within a frequency range of the radio-frequency signal. ### Claim 5 (depends on 3) The power amplifier according to claim 3, wherein the impedance of the first impedance circuit and the impedance of the second impedance circuit have a ratio of 9:1.5. ### Claim 6 (depends on 4) The power amplifier according to claim 4, wherein the impedance of the first impedance circuit and the impedance of the second impedance circuit have a ratio of 9:1.5. ### Claim 7 (depends on 1) The power amplifier according to claim 1, wherein an impedance of the first impedance circuit or an impedance of the second impedance circuit does not vary with frequency. ### Claim 8 (depends on 2) The power amplifier according to claim 2, wherein an impedance of the first impedance circuit or an impedance of the second impedance circuit does not vary with frequency. ### Claim 9 (depends on 3) The power amplifier according to claim 3, wherein an impedance of the first impedance circuit or an impedance of the second impedance circuit does not vary with frequency. ### Claim 10 (depends on 5) The power amplifier according to claim 5, wherein an impedance of the first impedance circuit or an impedance of the second impedance circuit does not vary with frequency. ### Claim 11 (depends on 1) The power amplifier according to claim 1, wherein an impedance of the first impedance circuit or an impedance of the second impedance circuit varies with frequency. ### Claim 12 (depends on 2) The power amplifier according to claim 2, wherein an impedance of the first impedance circuit or an impedance of the second impedance circuit varies with frequency. ### Claim 13 (depends on 3) The power amplifier according to claim 3, wherein an impedance of the first impedance circuit or an impedance of the second impedance circuit varies with frequency. ### Claim 14 (depends on 5) The power amplifier according to claim 5, wherein an impedance of the first impedance circuit or an impedance of the second impedance circuit varies with frequency. ### Claim 15 (depends on 1) The power amplifier according to claim 1, wherein the emitter of the first transistor is connected to the reference potential via the first impedance circuit and a first via, and the emitter of the second transistor is connected to the second potential via the second impedance circuit and a second via. ### Claim 16 (depends on 2) The power amplifier according to claim 2, wherein the emitter of the first transistor is connected to the reference potential via the first impedance circuit and a first via, and the emitter of the second transistor is connected to the second potential via the second impedance circuit and a second via. ### Claim 17 (depends on 3) The power amplifier according to claim 3, wherein the emitter of the first transistor is connected to the reference potential via the first impedance circuit and a first via, and the emitter of the second transistor is connected to the second potential via the second impedance circuit and a second via. ### Claim 18 (depends on 5) The power amplifier according to claim 5, wherein the emitter of the first transistor is connected to the reference potential via the first impedance circuit and a first via, and the emitter of the second transistor is connected to the second potential via the second impedance circuit and a second via. ### Claim 19 (depends on 1) The power amplifier according to claim 1, further comprising a final stage power amplification circuit, the final stage power amplification circuit comprising a third transistor having an emitter connected to the reference potential without an impedance circuit disposed between the emitter of the third transistor and the reference potential.