Integrated Doherty power amplifiers are provided herein. In certain implementations, a Doherty power amplifier includes a carrier amplification stage that generates a carrier signal, a peaking amplification stage that generates a peaking signal, and an antenna structure that combines the carrier signal and the peaking signal. The antenna structure radiates a transmit wave in which the carrier signal and the peaking signal are combined with a phase shift.

A circuit including an amplifier having an input and an output. The circuit also includes a current-to-voltage amplifier having an input. The circuit further includes a current mirror coupled between the output of the amplifier and the input of the current-to-voltage amplifier. The current mirror is configured to chop current flowing through the first current mirror.

A semiconductor chip includes a plurality of transistor rows. Corresponding to the plurality of transistor rows, a first bump connected to a collector of the transistor is arranged, and a second bump connected to an emitter is arranged. The transistor rows are arranged along sides of a convex polygon. A first land and a second land provided in a circuit board are connected to the first bump and the second bump, respectively. A first impedance conversion circuit connects the first land and the signal output terminal. A plurality of transistors in the transistor row are grouped into a plurality of groups, and the first impedance conversion circuit includes a reactance element arranged for each of the groups.

A semiconductor chip includes a plurality of transistor rows. Corresponding to the plurality of transistor rows, a first bump connected to a collector of the transistor is arranged, and a second bump connected to an emitter is arranged. The transistor rows are arranged along sides of a convex polygon. A first land and a second land provided in a circuit board are connected to the first bump and the second bump, respectively. A first impedance conversion circuit connects the first land and the signal output terminal. A plurality of transistors in the transistor row are grouped into a plurality of groups, and the first impedance conversion circuit includes a reactance element arranged for each of the groups.

An electrically conductive sub-collector layer is provided in a surface layer portion of a substrate. A collector layer, a base layer, and an emitter layer are located within the sub-collector layer when viewed in plan. The collector layer is connected to the sub-collector layer. An emitter electrode and a base electrode are long in a first direction when viewed in plan. The emitter electrode overlaps the emitter layer. The base electrode and the emitter electrode are discretely located away from each other in a second direction orthogonal to the first direction. A collector electrode is located on one side in the second direction with respect to the emitter electrode and is not located on the other side when viewed in plan. A base line is connected to the base electrode in a manner so as to adjoin a portion other than longitudinal ends of the base electrode.

Systems, methods, and apparatus for an improved body tie construction are described. The improved body tie construction is configured to have a lower resistance body tie exists when the transistor is “off” (Vg approximately 0 volts). When the transistor is “on” (Vg>Vt), the resistance to the body tie is much higher, reducing the loss of performance associated with presence of body tie. Space efficient Body tie constructions adapted for cascode configurations are also described.

Systems, methods, and apparatus for an improved body tie construction are described. The improved body tie construction is configured to have a lower resistance body tie exists when the transistor is “off” (Vg approximately 0 volts). When the transistor is “on” (Vg>Vt), the resistance to the body tie is much higher, reducing the loss of performance associated with presence of body tie. Space efficient Body tie constructions adapted for cascode configurations are also described.

Packaged RF transistor amplifiers are provided that include a flat no-lead overmold package that includes a die pad, a plurality of terminal pads and an overmold encapsulation that at least partially covers the die pad and the terminal pads and an RF transistor amplifier die mounted on the die pad and at least partially covered by the overmold encapsulation. These packaged RF transistor amplifiers may have an output power density of at least 3.0 W/mm.sup.2.

Packaged RF transistor amplifiers are provided that include a flat no-lead overmold package that includes a die pad, a plurality of terminal pads and an overmold encapsulation that at least partially covers the die pad and the terminal pads and an RF transistor amplifier die mounted on the die pad and at least partially covered by the overmold encapsulation. These packaged RF transistor amplifiers may have an output power density of at least 3.0 W/mm.sup.2.

Apparatus and methods for power amplifier systems with balun and shunt capacitor are disclosed. In certain embodiments, a front-end system includes a shunt capacitor, a balun having an input side and an output side, and power amplifier stages that operate in parallel with one another to amplify a radio frequency input signal. The power amplifier stages include a first power amplifier stage having a first output coupled to the shunt capacitor and to a first input terminal on the input side of the balun, and a second power amplifier stage having a second output coupled to a second input terminal on the input side of the balun.