An amplifier transistor operates in two operation modes having different characteristics. A first bias circuit including a first bias supply transistor supplies an output current of the first bias supply transistor to the amplifier transistor as a bias current. A second bias circuit including a second bias supply transistor supplies a portion of an output current of the second bias supply transistor to the amplifier transistor as a bias current. At least one of the first bias circuit and the second bias circuit is selected and operates in accordance with an operation mode of the amplifier transistor by using a bias control signal input to a bias control terminal. The second bias circuit includes a current path along which a portion of the output current of the second bias supply transistor is returned to the second bias circuit.

An amplifier transistor operates in two operation modes having different characteristics. A first bias circuit including a first bias supply transistor supplies an output current of the first bias supply transistor to the amplifier transistor as a bias current. A second bias circuit including a second bias supply transistor supplies a portion of an output current of the second bias supply transistor to the amplifier transistor as a bias current. At least one of the first bias circuit and the second bias circuit is selected and operates in accordance with an operation mode of the amplifier transistor by using a bias control signal input to a bias control terminal. The second bias circuit includes a current path along which a portion of the output current of the second bias supply transistor is returned to the second bias circuit.

A die is described comprising at least one 3-way Doherty amplifier comprising a main stage, a first peak stage and a second peak stage. An input is connected to an input network which is connected to the main stage, first peak stage and second peak stage. The input network includes a first impedance connected to an input of the first peak stage and providing a −90° phase shift and a second impedance connected to an input of the second peak stage and providing a 90° phase shift. An output is connected to an output network which is connected to the main stage, first peak stage and second peak stage. The output network includes a third impedance connected to the output of the first peak stage and providing a 180° phase shift and a fourth impedance connected to the output of the main stage and providing a 90° phase shift.

A die is described comprising at least one 3-way Doherty amplifier comprising a main stage, a first peak stage and a second peak stage. An input is connected to an input network which is connected to the main stage, first peak stage and second peak stage. The input network includes a first impedance connected to an input of the first peak stage and providing a −90° phase shift and a second impedance connected to an input of the second peak stage and providing a 90° phase shift. An output is connected to an output network which is connected to the main stage, first peak stage and second peak stage. The output network includes a third impedance connected to the output of the first peak stage and providing a 180° phase shift and a fourth impedance connected to the output of the main stage and providing a 90° phase shift.

A matching circuit includes an input terminal, an output terminal, a first impedance component, a first set of switching devices, a second impedance component, a second set of switching devices and a controller. The first impedance component includes a first terminal coupled between the input terminal and the output terminal, and a second terminal. The first set of switching devices is coupled to the second terminal of the first impedance component, the controller and a reference terminal. The second impedance component includes a first terminal coupled between the second terminal of the first impedance component and the first set of switching devices, and a second terminal. The second set of switching devices is coupled to the second terminal of the second impedance component, the controller and the reference terminal. The controller controls the first set of switch devices and the second set of switch devices according to a detection signal.

A matching circuit includes an input terminal, an output terminal, a first impedance component, a first set of switching devices, a second impedance component, a second set of switching devices and a controller. The first impedance component includes a first terminal coupled between the input terminal and the output terminal, and a second terminal. The first set of switching devices is coupled to the second terminal of the first impedance component, the controller and a reference terminal. The second impedance component includes a first terminal coupled between the second terminal of the first impedance component and the first set of switching devices, and a second terminal. The second set of switching devices is coupled to the second terminal of the second impedance component, the controller and the reference terminal. The controller controls the first set of switch devices and the second set of switch devices according to a detection signal.

In one embodiment, an electronic system includes a printed circuit board, one or more packaged semiconductor devices, and a vapor chamber having a top and a bottom and enclosing a sealed cavity that is partially filled with a coolant. The vapor chamber comprises a thermo-conductive and electro-conductive material. The top of the vapor chamber has one or more depressions formed therein, each depression receiving and thermo-conductively connected to at least part of a bottom of a corresponding packaged semiconductor device, which is mounted through a corresponding aperture in the PCB. A heat sink may be thermo-conductively attached to the bottom of the vapor chamber.

A module substrate has first and second main surfaces that on opposite sides of the module substrate, a resin member that covers the second main surface, and a plurality of post electrodes that are spaced apart from each other on the second main surface and penetrate through the resin member from the second main surface. The plurality of post electrodes includes a first post electrode and a first recess recessed toward the second main surface and formed in at least part of a region of the surface of the resin member that surrounds a leading end part of the first post electrode.

A radio-frequency module includes an integrated circuit (IC) device and an external inductor provided outside the IC device. The IC device includes a plurality of low-noise amplifiers, one or more inductors, and a switching circuit. The plurality of low-noise amplifiers includes a plurality of transistors in one to one correspondence. The one or more inductors are coupled to one or more of the plurality of transistors. Each inductor is coupled to the emitter or source of a corresponding one of the plurality of transistors. The switching circuit is coupled between the emitter or source of each of the plurality of transistors and the external inductor. The external inductor is coupled between the switching circuit and ground in series with each of the one or more inductors via the switching circuit.

A radio-frequency module includes an integrated circuit (IC) device and an external inductor provided outside the IC device. The IC device includes a plurality of low-noise amplifiers, one or more inductors, and a switching circuit. The plurality of low-noise amplifiers includes a plurality of transistors in one to one correspondence. The one or more inductors are coupled to one or more of the plurality of transistors. Each inductor is coupled to the emitter or source of a corresponding one of the plurality of transistors. The switching circuit is coupled between the emitter or source of each of the plurality of transistors and the external inductor. The external inductor is coupled between the switching circuit and ground in series with each of the one or more inductors via the switching circuit.