There are included a first amplifier and a second amplifier electrically connected to a stage subsequent to the first amplifier, a third amplifier and a fourth amplifier electrically connected to a stage subsequent to the third amplifier, a phase shifter that makes a phase of a radio-frequency signal passing through a first path different from a phase of a radio-frequency signal passing through a second path, a first bias circuit that supplies a bias to the first amplifier and the third amplifier, a second bias circuit that supplies a bias to the first amplifier and the second amplifier, and a third bias circuit that supplies a bias to the third amplifier and the fourth amplifier. The second amplifier includes a second transistor, the fourth amplifier includes a fourth transistor, the second bias circuit includes a sixth transistor, and the third bias circuit includes a seventh transistor.

An apparatus is disclosed for transmission setting selection. In an example aspect, an apparatus includes a wireless interface device with a communication processor and a radio-frequency front-end. The communication processor is configured to provide a signal. The radio-frequency front-end is coupled to the communication processor and configured to accept the signal. The radio-frequency front-end includes an amplifier configured to amplify the signal based on one or more amplifier settings. The wireless interface device is configured to adjust the one or more amplifier settings responsive to an output power being changed with a gain being unchanged.

Aspects of this disclosure relate to an impedance transformation circuit for use in an amplifier, such as a low noise amplifier. The impedance transformation circuit includes a matching circuit including a first inductor. The impedance transformation circuit also includes a second inductor. The first and second inductors are magnetically coupled to each other to provide negative feedback to linearize the amplifier.

Aspects of this disclosure relate to an impedance transformation circuit for use in an amplifier, such as a low noise amplifier. The impedance transformation circuit includes a matching circuit including a first inductor. The impedance transformation circuit also includes a second inductor. The first and second inductors are magnetically coupled to each other to provide negative feedback to linearize the amplifier.

Leadless power amplifier (PA) packages having topside termination interposer (TTI) arrangements, and associated fabrication methods, are disclosed. Embodiments of the leadless PA package include a base flange, a first set of interposer mount pads, a first RF power die, a package body. The first RF power die is attached to a die mount surface of the base flange and electrically interconnected with the first set of interposer mount pads. The TTI arrangement is electrically coupled to the first set of interposer mount pads and projects therefrom in the package height direction. The package body encloses the first RF power die and having a package topside surface opposite the lower flange surface. Topside input/output terminals of the PA package are accessible from the package topside surface and are electrically interconnected with the first RF power die through the TTI arrangement and the first set of interposer mount pads.

Leadless power amplifier (PA) packages having topside termination interposer (TTI) arrangements, and associated fabrication methods, are disclosed. Embodiments of the leadless PA package include a base flange, a first set of interposer mount pads, a first RF power die, a package body. The first RF power die is attached to a die mount surface of the base flange and electrically interconnected with the first set of interposer mount pads. The TTI arrangement is electrically coupled to the first set of interposer mount pads and projects therefrom in the package height direction. The package body encloses the first RF power die and having a package topside surface opposite the lower flange surface. Topside input/output terminals of the PA package are accessible from the package topside surface and are electrically interconnected with the first RF power die through the TTI arrangement and the first set of interposer mount pads.

A semiconductor-on-insulator die can include a power amplifier configured to amplify a radio frequency input signal having a fundamental frequency. The die can further include an output matching circuit including first and second second-order harmonic rejection circuits configured to resonate at about two times the fundamental frequency and a third order harmonic rejection circuit configured to resonate at about three times the fundamental frequency.

A semiconductor-on-insulator die can include a power amplifier configured to amplify a radio frequency input signal having a fundamental frequency. The die can further include an output matching circuit including first and second second-order harmonic rejection circuits configured to resonate at about two times the fundamental frequency and a third order harmonic rejection circuit configured to resonate at about three times the fundamental frequency.

A stacked amplifier circuit includes an input stage having first and second input ports respectively defined by inputs of first and second transistors. A transformer arrangement includes first and second primary windings and first and second secondary windings. The first secondary winding is connected to an output of the first input transistor and the second secondary winding is connected to an output of the second input transistor. Portions of the magnetic fields generated by the primary windings couple to their respective secondary windings. An output stage is AC coupled to the first and second secondary windings and has an output connected to the first and second primary windings. The input stage and the output stage are arranged in a stacked configuration such that a bias current of the output stage is reused as bias current for the input stage.

A bipolar transistor includes a collector layer, a base layer, and an emitter layer that are formed in this order on a compound semiconductor substrate. The emitter layer is disposed inside an edge of the base layer in plan view. A base electrode is disposed on partial regions of the emitter layer and the base layer so as to extend from an inside of the emitter layer to an outside of the base layer in plan view. An insulating film is disposed between the base electrode and a portion of the base layer, with the portion not overlapping the emitter layer. An alloy layer extends from the base electrode through the emitter layer in a thickness direction and reaches the base layer. The alloy layer contains at least one element constituting the base electrode and elements constituting the emitter layer and the base layer.