# US 11,444,582 B2 · Power amplifier circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,444,582 B2 - Document ID: US11444582B2 - Status: Granted - Kind: B2 - Application number: 17/159,953 - Filed: 2021-01-27 - Published: 2021-05-20 - Granted: 2022-09-13 - Earliest claimed: 2018-08-10 - Assignees: Murata Manufacturing Co., Ltd. - Applicants: Murata Manufacturing Co., Ltd. - Inventors: Yuri Honda; Kenji Mukai; Fumio Harima - Web page: https://patentgrep.com/patent/US11444582B2 ## CPC - H03F 1/3205: {in field-effect transistor amplifiers} - 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 1/32: Modifications of amplifiers to reduce non-linear distortion (by negative feedback H03F1/34) - H03F 1/56: Modifications of input or output impedances, not otherwise provided for - 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 2200/451: the amplifier being a radio frequency amplifier - H03F: AMPLIFIERS ## Abstract A power amplifier circuit includes an amplifier transistor, a bias circuit that supplies a bias current or voltage to the amplifier transistor, and a resistance element connected between a base of the amplifier transistor and the bias circuit. The bias circuit includes a voltage generation circuit, a first transistor having a base to which a first direct-current voltage is supplied and an emitter from which the bias current or voltage is supplied, a second transistor having a base to which a second direct-current voltage is supplied and an emitter connected to the emitter of the first transistor, a signal supply circuit that supplies an input signal to the base of the second transistor, and an impedance circuit disposed between the base of the first transistor and the base of the second transistor. ## Claims ### Claim 1 A power amplifier circuit comprising: an amplifier transistor having a base or a gate to which an input signal is supplied, and having a collector or a drain from which an amplified signal is output, the amplified signal being obtained by amplifying the input signal; a bias circuit configured to supply a bias current or a bias voltage to the base or the gate of the amplifier transistor; and a resistance element connected in series between the base of the amplifier transistor and the bias circuit, or between the gate of the amplifier transistor and the bias circuit, wherein: the bias circuit comprises: a first transistor having a base or a gate to which a first direct-current voltage is supplied, and having an emitter or a source from which the bias current or the bias voltage is supplied to the base or the gate of the amplifier transistor via the resistance element; a second transistor having a base or a gate to which a second direct-current voltage is supplied, and having an emitter or a source connected to the emitter or the source of the first transistor; a signal supply circuit disposed between the base or the gate of the second transistor and a supply path of the input signal to the amplifier transistor, the signal supply circuit being configured to supply the input signal to the base or the gate of the second transistor; and an impedance circuit disposed between the base or the gate of the first transistor and the base or the gate of the second transistor. ### Claim 2 (depends on 1) The power amplifier circuit according to claim 1, wherein the impedance circuit comprises a resistance element. ### Claim 3 (depends on 1) The power amplifier circuit according to claim 1, wherein the signal supply circuit comprises a capacitance element. ### Claim 4 (depends on 1) The power amplifier circuit according to claim 1, wherein the signal supply circuit comprises a capacitance element and a resistance element connected in series. ### Claim 5 (depends on 1) The power amplifier circuit according to claim 1, wherein: the impedance circuit comprises a resistance element having a first end connected to the base or the gate of the first transistor, and having a second end connected to the base or the gate of the second transistor, and the signal supply circuit comprises a capacitance element having a first end connected to the supply path, and having a second end connected to the second end of the resistance element of the impedance circuit. ### Claim 6 (depends on 4) The power amplifier circuit according to claim 4, further comprising a capacitance element in the supply path connected between the first end of the capacitance element of the signal supply circuit and the base of the amplifier transistor, or between the first end of the capacitance element of the signal supply circuit and the gate of the amplifier transistor. ### Claim 7 (depends on 1) The power amplifier circuit according to claim 1, further comprising: a second bias circuit configured to supply a second bias current or a second bias voltage to the base or the gate of the amplifier transistor, wherein: the second bias circuit comprises: a third transistor having a base or a gate to which a third direct-current voltage is supplied, and having an emitter or a source from which the second bias current or the second bias voltage is supplied to the base or the gate of the amplifier transistor via the resistance element, when the power amplifier circuit operates in a first mode, the second voltage generation circuit is configured to be kept in an off state by a second control signal, and when the power amplifier circuit operates in a second mode, the second voltage generation circuit is configured to be kept in an on state by the second control signal. ### Claim 8 (depends on 7) The power amplifier circuit according to claim 7, wherein the second bias circuit further comprises: a second voltage generation circuit configured to generate the third direct-current voltage in accordance with the second control signal. ### Claim 9 (depends on 7) The power amplifier circuit according to claim 7, wherein the second mode is a mode in which a power level of the amplified signal is less than a power level of the amplified signal in the first mode. ### Claim 10 (depends on 1) The power amplifier circuit according to claim 1, further comprising: a second amplifier transistor having a base or a gate to which the input signal is supplied, and having a collector or a drain connected to the collector or the drain of the amplifier transistor; a second bias circuit configured to supply a second bias current or a second bias voltage to the base or the gate of the second amplifier transistor; and a second resistance element connected in series between the base of the second amplifier transistor and the second bias circuit, or between the gate of the second amplifier transistor and the second bias circuit, wherein: the second bias circuit comprises: a third transistor having a base or a gate to which a third direct-current voltage is supplied, and having an emitter or a source from which the second bias current or the second bias voltage is supplied to the base or the gate of the second amplifier transistor via the second resistance element; and a fourth transistor having a base or a gate connected to the signal supply circuit, and having an emitter or a source connected to the emitter or the source of the third transistor, and the second voltage generation circuit is configured to be kept in an on state by a second control signal when the power amplifier circuit operates in both a first mode and a second mode. ### Claim 11 (depends on 10) The power amplifier circuit according to claim 10, wherein the second bias circuit further comprises: a second voltage generation circuit configured to generate the third direct-current voltage in accordance with the second control signal. ### Claim 12 (depends on 10) The power amplifier circuit according to claim 10, wherein the second mode is a mode in which a power level of the amplified signal is less than a power level of the amplified signal in the first mode. ### Claim 13 (depends on 1) The power amplifier circuit according to claim 1, wherein the amplifier transistor is a bipolar transistor. ### Claim 14 (depends on 1) The power amplifier circuit according to claim 1, wherein the amplifier transistor is a field effect transistor. ### Claim 15 (depends on 1) The power amplifier circuit according to claim 1, wherein the first transistor is a bipolar transistor. ### Claim 16 (depends on 1) The power amplifier circuit according to claim 1, wherein the first transistor is a field effect transistor. ### Claim 17 (depends on 1) The power amplifier circuit according to claim 1, wherein the second transistor is a bipolar transistor. ### Claim 18 (depends on 1) The power amplifier circuit according to claim 1, wherein the second transistor is a field effect transistor.