An amplifier circuit includes: a transistor provided between an input terminal and an output terminal and having a gate connected to the input terminal, a source connected to a ground, and a drain connected to the output terminal; an inductor connected between the source and the ground; an inductor connected between the gate and the input terminal, and switches connected to at least one of the inductors and configured to change a mutual inductance of the inductors.

An amplifier circuit includes: a transistor provided between an input terminal and an output terminal and having a gate connected to the input terminal, a source connected to a ground, and a drain connected to the output terminal; an inductor connected between the source and the ground; an inductor connected between the gate and the input terminal, and switches connected to at least one of the inductors and configured to change a mutual inductance of the inductors.

A power amplifier circuit includes a first transistor disposed on a semiconductor substrate; a second transistor disposed on the semiconductor substrate and configured to supply a bias current based on a first current which is a part of a control current to the first transistor; a third transistor disposed on the semiconductor substrate and having a collector configured to be supplied with a second current which is a part of the control current and an emitter configured to output a third current based on the second current; a first bump electrically connected to an emitter of the first transistor and disposed so as to overlap a first disposition area in which the first transistor is disposed in plan view of the semiconductor substrate; and a second bump disposed so as to overlap a second disposition area in which the third transistor is disposed in the plan view.

A power amplifier circuit includes a first transistor disposed on a semiconductor substrate; a second transistor disposed on the semiconductor substrate and configured to supply a bias current based on a first current which is a part of a control current to the first transistor; a third transistor disposed on the semiconductor substrate and having a collector configured to be supplied with a second current which is a part of the control current and an emitter configured to output a third current based on the second current; a first bump electrically connected to an emitter of the first transistor and disposed so as to overlap a first disposition area in which the first transistor is disposed in plan view of the semiconductor substrate; and a second bump disposed so as to overlap a second disposition area in which the third transistor is disposed in the plan view.

Methods and devices for reducing gate node instability of a differential cascode amplifier are presented. Ground return loops, and therefore corresponding parasitic inductances, are eliminated by using voltage symmetry at nodes of two cascode amplification legs of the differential cascode amplifier. Series connected capacitors are coupled between gate nodes of pairs of cascode amplifiers of the two cascode amplification legs so to create a common node connecting the two capacitors. In order to reduce peak to peak voltage variation at the common node under large signal conditions, a shunting capacitor is connected to the common node.

An embodiment of the present disclosure relates to a method of controlling a power amplifier (PA). The PA can comprise a main PA path and an auxiliary PA path. The auxiliary PA path can have a plurality of turn-on settings. The method can comprise: determining a power back off gain and a lower bound gain for the PA; and performing an iterative auxiliary PA turn-on setting selection process. The selection process can comprise: determining an instantaneous power input to the PA; based on the instantaneous power input, choosing a turn-on setting in the plurality of turn-on settings of the auxiliary PA path that causes an instantaneous gain of the PA to be between the power back off gain and the lower bound gain; and applying the chosen turn-on setting to the auxiliary PA path.

A power amplifier arrangement (100) for amplifying an input signal (Pin) to produce an output signal (Pout) is disclosed. The amplifier arrangement (100) comprise an input port (IN) for receiving the input signal; an output transmission line (110) having a first terminal (111) and a second terminal (112); an output port (OUT) coupled to the second terminal (112) of the output transmission line (110) for providing the output signal; and a plurality N of amplifying devices (121, 122, . . . 12N) distributed along the output transmission line (110). The power amplifier arrangement (100) is configured such that the plurality N of amplifying devices are active sequentially for amplifying the input signal with increasing amplitude of the input signal.

A power amplifier arrangement (100) for amplifying an input signal (Pin) to produce an output signal (Pout) is disclosed. The amplifier arrangement (100) comprise an input port (IN) for receiving the input signal; an output transmission line (110) having a first terminal (111) and a second terminal (112); an output port (OUT) coupled to the second terminal (112) of the output transmission line (110) for providing the output signal; and a plurality N of amplifying devices (121, 122, . . . 12N) distributed along the output transmission line (110). The power amplifier arrangement (100) is configured such that the plurality N of amplifying devices are active sequentially for amplifying the input signal with increasing amplitude of the input signal.

Remote compensators for mobile devices are provided. In certain embodiments, a remote compensator includes a first balun, a cable-side circulator including an output that provides a transmit signal and an input that receives an amplified receive signal, a first phase shifter, a second phase shifter, a first antenna-side circulator, a second antenna-side circulator, a push-pull amplifier, and a receive amplifier that generates the amplified receive signal by amplifying a first receive signal from the first antenna-side circulator and a second receive signal from the second antenna-side circulator. The push-pull amplifier includes an input that receives the transmit signal, a first output connected to a first end of a winding of the first balun through the first antenna-side circulator and the first phase shifter, and a second output connected to a second end of the winding of the first balun through the second phase shifter and the second antenna-side circulator.

Remote compensators for mobile devices are provided. In certain embodiments, a remote compensator includes a first balun, a cable-side circulator including an output that provides a transmit signal and an input that receives an amplified receive signal, a first phase shifter, a second phase shifter, a first antenna-side circulator, a second antenna-side circulator, a push-pull amplifier, and a receive amplifier that generates the amplified receive signal by amplifying a first receive signal from the first antenna-side circulator and a second receive signal from the second antenna-side circulator. The push-pull amplifier includes an input that receives the transmit signal, a first output connected to a first end of a winding of the first balun through the first antenna-side circulator and the first phase shifter, and a second output connected to a second end of the winding of the first balun through the second phase shifter and the second antenna-side circulator.