Abstract: A first transmission line transformer receives and outputs an unbalanced signal and performs impedance transformation. A second transmission line transformer performs unbalanced-to-balanced transformation. The first transmission line transformer includes a first main line and a first sub-line. The direction of the first main line is identical to the direction of the first sub-line. An end of the first sub-line is grounded. An end of the first main line is coupled to the unbalanced-signal input/output node. The second transmission line transformer includes a second main line and a second sub-line. The direction of the second main line is identical to a direction of the second sub-line. An end of the second main line and the second sub-line are grounded. An end of the second main line and the second sub-line are coupled to the balanced-signal input/output nodes.

Abstract: A power amplifier unit includes a power amplifier circuit that amplifies a radio-frequency input signal, a first impedance matching circuit that performs impedance matching for an output signal of the power amplifier circuit, a second-order harmonic termination circuit on an output side of the first impedance matching circuit and that reflects at least part of even-ordered and odd-ordered harmonics contained in a signal input from the first impedance matching circuit to output the at least part of the harmonics from an input terminal as a radio-frequency signal and outputs a radio-frequency signal containing a fundamental and the remainder of the harmonics from an output terminal, and a filter that is on a subsequent stage of the second-order harmonic termination circuit, that attenuates at least part of the even-ordered and odd-ordered harmonics, and that outputs a radio-frequency signal including the fundamental and the remainder of the even-ordered and odd-ordered harmonics.

Abstract: A transmission circuit appropriately controls output power in response to fluctuations in the impedance of a load. A transmission circuit includes: a transistor to which a bias current IB1 is supplied and that amplifies and outputs an input signal RFin; a transistor to which a bias current IB2 is supplied, that has a collector connected to the collector of the transistor, and that amplifies and outputs the input signal; a current generation circuit that generates a current I2 on the basis of a current I1 from the emitter of the transistor; and a bias control circuit that outputs a first bias control signal for controlling the bias current IB1 and a second bias control signal for controlling the bias current IB2 on the basis of the current I2.

Abstract: A bond layer including at least one metal region in a plan view is disposed on a surface layer portion of a substrate formed from a semiconductor. A semiconductor element is disposed on the bond layer and includes a first transistor disposed on a first metal region that is a metal region as the at least one metal region of the bond layer and including a collector layer electrically coupled to the first metal region, a base layer disposed on the collector layer, and an emitter layer disposed on the base layer. A first emitter electrode is disposed on the emitter layer of the first transistor. A first conductor protrusion is disposed on the first emitter electrode. The thermal conductivity of the semiconductor material of the surface layer portion is higher than that of each of the collector layer, the base layer, and the emitter layer of the first transistor.

Abstract: A power amplifier circuit includes an amplifier that receives an input signal with an alternating current and outputs an output signal obtained by amplifying power of the input signal to a first node; an inductive element that is connected between the first node and a second node; and a variable capacitor that is connected between the second node and a reference potential, and whose electrostatic capacitance increases as power of the output signal increases.

Abstract: A first transmission line and a third transmission line are disposed at different positions in a thickness direction of a substrate. The third transmission line includes a first end portion connected to one end portion of the first transmission line, and a second end portion that is grounded. The first transmission line is electromagnetically coupled to the third transmission line. The first transmission line has a coil pattern and the third transmission line has a partially open loop pattern.

Abstract: Provided is a power amplifier circuit that can increase output power and also reduce the effect of intermodulation distortion. The power amplifier circuit includes a power divider, a distortion compensation circuit provided on the secondary path, a power combiner, and a first amplifier configured. The distortion compensation circuit includes a generation circuit configured to generate the second-harmonic wave of the input signal, a filter circuit configured to attenuate the fundamental wave and pass the second-harmonic wave, and a phase adjustment circuit configured to adjust the phase of the second-harmonic wave.

Abstract: A power amplifier circuit includes a substrate and a semiconductor chip disposed on or above the substrate. The semiconductor chip includes a power amplifier unit that amplifies an RF signal, a ground terminal to which a ground of the power amplifier unit is coupled, and a first circuit element having a first end electrically coupled to the ground terminal without any portion outside the semiconductor chip interposed therebetween, and having a second end. The substrate includes a second circuit element having a first end electrically coupled to an output of the power amplifier unit and a second end electrically coupled to the second end of the first circuit element. The first and second circuit elements constitute a harmonic wave termination circuit. The harmonic wave termination circuit reflects, to the power amplifier unit, a harmonic wave component of the amplified RF signal output from the power amplifier unit.

Abstract: A power amplifier circuit includes amplifying transistors electrically cascade-connected, amplifying a signal supplied to a base, and outputting an amplified signal; a first resistive element having end parts connected to the base of a first amplifying transistor; a second resistive element having end parts connected to the base of a second amplifying transistor, which is an amplifying transistor located closer to an input side than the first amplifying transistor; a first bias supplying transistor having an emitter connected to one of the end parts of the first resistive element; a second bias supplying transistor having an emitter connected to one of the end parts of the second resistive element; and a bias current compensation transistor having a base connected to the end part of the first resistive element, a collector connected to the end part of the second resistive element, and an emitter connected to ground.

Abstract: A power amplifier unit includes a power amplifier circuit that amplifies a radio-frequency input signal, a first impedance matching circuit that performs impedance matching for an output signal of the power amplifier circuit, a second-order harmonic termination circuit on an output side of the first impedance matching circuit and that reflects at least part of even-ordered and odd-ordered harmonics contained in a signal input from the first impedance matching circuit to output the at least part of the harmonics from an input terminal as a radio-frequency signal and outputs a radio-frequency signal containing a fundamental and the remainder of the harmonics from an output terminal, and a filter that is on a subsequent stage of the second-order harmonic termination circuit, that attenuates at least part of the even-ordered and odd-ordered harmonics, and that outputs a radio-frequency signal including the fundamental and the remainder of the even-ordered and odd-ordered harmonics.

Abstract: An active balun circuit includes first and second transistors having emitters electrically coupled to each other and configured to output differential signals and a circuit element coupled between the connection point of the emitter of the first transistor and the emitter of the second transistor and a reference potential. The impedance of the circuit element at a particular frequency of the input signal appears significantly larger than impedances at other frequencies. An input signal from an input terminal is inputted to the base of the first transistor. The reference potential is applied to the base of the second transistor. A supply voltage is applied to the collector of the first transistor and the collector of the second transistor. A signal from the collector of the first transistor and a signal from the collector of the second transistor are outputted as the differential signals.

Abstract: A first transmission line and a second transmission line that are connected in series to each other are disposed at different positions in a thickness direction of a substrate. A third transmission line is disposed between the first transmission line and the second transmission line in the thickness direction of the substrate. The third transmission line includes a first end portion connected to one end portion of the first transmission line, and a second end portion that is AC-grounded. The first transmission line and the second transmission line are electromagnetically coupled to the third transmission line.

Abstract: The present disclosure facilitates impedance matching between a power amplifier and filters. A radio-frequency circuit includes a power amplifier, a plurality of transmit filters, a switch, a plurality of first matching networks, and a second matching network. The switch switches the plurality of transmit filters to be coupled to the power amplifier. The plurality of first matching networks are coupled between the plurality of transmit filters and the switch. The second matching network is coupled between the power amplifier and the switch. The second matching network includes a transmission line transformer.

Abstract: A first primary line has a first node at one end and a third node at another end and transmits a radio-frequency signal between the first node and the third node. A second primary line has a second node at one end and a fourth node at another end and transmits a radio-frequency signal between the second node and the fourth node. A first secondary line has a portion connected to the second node and is electromagnetically coupled to the first primary line. The second secondary line has a portion connected to the first node and has another end connected to a portion of the first secondary line. The second secondary line is electromagnetically coupled to the second primary line. A first capacitor is connected in parallel to a portion of the second primary line or a portion of the second secondary line.

Abstract: Provided is a power amplifier circuit that reduces the effect of intermodulation distortion without necessarily increase in the circuit size. The power amplifier circuit includes a first amplifier that amplifies a first signal and output a second signal, an extraction circuit that extracts a second-harmonic wave included in the second signal, a phase adjustment circuit that adjusts the phase of the extracted second-harmonic wave, and a power combiner that combines the second-harmonic wave of the adjusted phase with a third signal and output the first signal.

Abstract: A power amplification module includes: a first bipolar transistor in which a radio frequency signal is input to a base and an amplified signal is output from a collector; a second bipolar transistor that is thermally coupled with the first bipolar transistor and that imitates operation of the first bipolar transistor; a third bipolar transistor in which a first control voltage is supplied to a base and a first bias current is output from an emitter; a first resistor that generates a third control voltage corresponding to a collector current of the second bipolar transistor at a second terminal; and a fourth bipolar transistor in which a power supply voltage is supplied to a collector, the third control voltage is supplied to a base, and a second bias current is output from an emitter.

Abstract: Provided is a power amplifier circuit that can increase output power and also reduce the effect of intermodulation distortion. The power amplifier circuit includes a power divider, a distortion compensation circuit provided on the secondary path, a power combiner, and a first amplifier configured. The distortion compensation circuit includes a generation circuit configured to generate the second-harmonic wave of the input signal, a filter circuit configured to attenuate the fundamental wave and pass the second-harmonic wave, and a phase adjustment circuit configured to adjust the phase of the second-harmonic wave.

Abstract: A power amplifier circuit includes an amplifier transistor which amplifies a radio frequency signal applied to its base and outputs the amplified signal; a resistance element having a first end, and a second end electrically connected to the base of the amplifier transistor; a first bias transistor having a collector to which a first voltage is applied, a base to which a first bias voltage is applied, and an emitter electrically connected to the first end of the resistance element and which supplies a bias current to the base of the amplifier transistor through the resistance element; and a second bias transistor having an emitter electrically connected to the emitter of the first bias transistor and the first end of the resistance element, a base to which a second bias voltage is applied, and a collector to which a second voltage lower than the first voltage is applied.

Abstract: A power amplifier that includes a substrate, and an emitter layer, a base layer, and a collector layer laminated in this order on a major surface of the substrate includes an electrical insulator provided adjacent to the emitter layer, an emitter electrode provided between the substrate and both the emitter layer and the electrical insulator, a base electrode electrically connected to the base layer, and a collector electrode electrically connected to the collector layer. The emitter electrode, the electrical insulator, and the base layer are provided between the substrate and the base electrode in a direction perpendicular to the major surface of the substrate.

Abstract: An output matching circuit includes: a converter electrically connected to an output end of a power amplifier element to convert an impedance of the output end to an impedance higher than the impedance of the output end by magnetic coupling; and a first filter circuit electrically connected between the output end of the power amplifier element and the converter to make a short circuit in a frequency band different from a predetermined transmission frequency band.