Abstract: A radio frequency circuit includes power amplifiers, a transformer, a filter having a band A as a pass band, a filter having a band B as a pass band, a filter having a band C as a pass band, matching circuits connected to one end of an output side coil, and matching circuits connected to the other end of the output side coil. The matching circuit includes a capacitor disposed at a first path, a switch connected to the first path and a ground, a switch and an inductor connected in series, and the matching circuit includes a capacitor disposed at a second path, and a switch and an inductor connected in series, and the matching circuit includes a switch connected to a third path and the ground.

Abstract: A power amplifier circuit includes an external input terminal, an external output terminal, a power amplifier connected to the external input terminal, power amplifiers, a power supply terminal connected to the power amplifier, and a power supply terminal connected to the power amplifier. The power amplifiers are connected in parallel with each other between the power amplifier and the external output terminal. A first power supply voltage which is variable to multiple discrete first voltage levels is supplied to the power amplifier via the power supply terminal. A second power supply voltage which is variable to multiple discrete second voltage levels is supplied to the power amplifier via the power supply terminal. The multiple discrete second voltage levels are different from the multiple discrete first voltage levels.

Abstract: A power amplifier circuit includes a power amplifier and an external power terminal that receives a power supply voltage from a power supply circuit. The power amplifier includes two amplifying elements and, a limiter, and an RC circuit. The amplifying elements respectively include first and second input terminals, first and second output terminals, and first and second power terminals. The limiter restricts the power supply voltage to a predetermined range and outputs the restricted power supply voltage. The RC circuit is connected in parallel with the limiter. The first input terminal is connected to an external input terminal. The first output terminal is connected to the second input terminal. The second output terminal is connected to an external output terminal. The first power terminal is connected to the external power terminal via the limiter. The second power terminal is connected to the external power terminal.

Abstract: A power amplifier circuit that includes an external input terminal and an external output terminal; a first power amplifier, a second power amplifier, a third power amplifier, and a fourth power amplifier; a transformer including an input-side coil and an output-side coil; and a first transmission line, the external input terminal being connected to an input terminal of the first and second power amplifiers, an output terminal of the first power amplifier is connected to an input terminal of the third and fourth power amplifiers, output terminals of the third and fourth power amplifiers being connected to a first and second end of the input-side coil respectively, the external output terminal being connected to a first end of the output-side coil, and an output terminal of the second power amplifier being connected to a second end of the output-side coil via the first transmission line.

Abstract: A power amplifier circuit includes external input and output terminals; a first power amplifier with first input and output terminals, the first input terminal being connected to the external input terminal, the first output terminal being connected to the external output terminal; a second power amplifier having second input and output terminals, the second input terminal being connected to the external input terminal, the second output terminal being connected to the external output terminal; a power supply terminal that receives a power supply voltage that is supplied to the first power amplifier and controllably supplied to the second power amplifier; and a switch having first and second terminals, the first terminal being connected to the power supply terminal, the second terminal being connected to the second power amplifier.

Abstract: A power amplifier circuit includes an amplifier transistor having a collector terminal, an emitter terminal, and a base terminal, bias circuits, and a current limiter circuit. The bias circuit includes a constant current amplifier transistor that supplies direct-current bias current from an emitter terminal to the base terminal. The current limiter circuit includes a current limiting transistor an emitter terminal of which is connected to the bias circuit, a resistive element connected between the current limiting transistor and a power supply terminal, and a resistive element connected between the current limiting transistor and the constant current amplifier transistor. The bias circuit includes a constant current amplifier transistor that supplies direct-current bias current i3 from an emitter terminal to the base terminal.

Abstract: An amplifier module includes an antenna that includes four power feed points, and four power amplifiers. Output ends of the four power amplifiers are connected to the four power feed points in a one-to-one relationship. The four power feed points are arranged rotationally symmetrically around a center of the antenna when a main surface of the antenna is viewed in plan.

Abstract: An amplifier circuit includes amplifiers, transformers, and a transmission line. A first end of an input-side coil is connected to an output terminal of the amplifier, a second end of the input-side coil is connected to an output terminal of the amplifier via the transmission line, a first end of an input-side coil is connected to an output terminal of the amplifier, a second end of the input-side coil is connected to the output terminal of the amplifier via the transmission line, a first end of an output-side coil is connected to an output terminal, a second end of the output-side coil is connected to a ground, a first end of an output-side coil is connected to an output terminal, and a second end of the output-side coil is connected to the ground.

Abstract: A radio frequency circuit includes a carrier amplifier, a peak amplifier, a transformer, and an impedance converting circuit. One end of an input coil is connected to an output of the carrier amplifier, one end of an output coil is connected to an output terminal. The impedance converting circuit includes main and auxiliary lines. One end of the main line is connected to an output of the peak amplifier, and the other end of the main line is connected to the other end of the input coil. One end of the auxiliary line is connected to the one end of the main line, and the other end of the auxiliary line is connected to ground. A first direction from the one end to the other end of the main line, and a second direction from the other end to the one end of the auxiliary line (302) are the same.

Abstract: A radio-frequency module includes a module substrate, a carrier amplifier and a peak amplifier, a transformer, and a phase adjustment circuit. The carrier amplifier and the peak amplifier are included in a semiconductor IC. One end of an input-side coil is connected to an output terminal of the carrier amplifier. One end of the output-side coil is connected to a signal output terminal.

Abstract: A radio frequency circuit includes carrier amplifiers and peak amplifiers, transformers, a signal output terminal connected to a first end of an output-side coil, an LC series circuit, and a capacitor. An input-side coil is connected, at its first end, to the carrier amplifier, and is connected, at its second end, to the carrier amplifier. An input-side coil is connected, at its first end, to the peak amplifier, and is connected, at its second end, to the peak amplifier. The LC series circuit is connected between the peak amplifier and the ground. The capacitor is connected to a second end of the output-side coil and a first end of an output-side coil. The output-side coil is connected, at its second end, to the ground.