An amplifier comprising a current-biased active device, a voltage-biased active device, the voltage-biased active device and the current-biased active device are connected in series, to form a cascade of active devices, and an input terminal and an output terminal, the cascade of active devices connected between the input terminal and the output terminal, having an output terminal for driving a load impedance with an output signal in response to an input signal applied to the input terminal.

A transformer has a first winding, a second winding, a third winding, a fourth winding and a fifth winding. The fifth winding has a first part and a second part serially connected to the first part. The first part is magnetically coupled to the second winding and magnetically isolated from the first winding, and the second part is magnetically coupled to the fourth winding and magnetically isolated from the third winding. The second winding is positioned between the first winding and the first part, the first winding is positioned adjacent to the second winding, and the second winding is positioned adjacent to the first part. The fourth winding is positioned between the third winding and the second part, the third winding is positioned adjacent to the fourth winding, and the fourth winding is positioned adjacent to the second part.

Apparatus and methods for quadrature combined Doherty amplifiers are provided herein. In certain embodiments, a separator is used to separate a radio frequency (RF) input signal into a plurality of input signal components that are amplified by a pair of Doherty amplifiers operating in quadrature. Additionally, a combiner is used to combine a plurality of output signal components generated by the pair of Doherty amplifiers, thereby generating an RF output signal exhibiting quadrature balancing.

Wideband power combiners and splitters are provided herein. In certain embodiments, a power combiner/splitter is implemented with a first coil connecting a first port and a second port, and a second coil connecting a third port and a fourth port. The first coil and the second coil are inductively coupled to one another. For example, the first coil and the second coil can be formed using adjacent conductive layers of a semiconductor chip, an integrated passive device, or a laminate. The power combiner/splitter further includes a fifth port tapping a center of the first coil and a sixth port tapping a center of the second coil. The fifth port and the sixth port serve to connect capacitors and/or other impedance to the center of the coils to thereby provide wideband operation.

Methods and apparatus for providing high efficiency power amplifiers for both high and low output power levels are disclosed. An example apparatus includes a first amplifier to amplify a signal from a host device; and transmit the amplified signal to an antenna; a second amplifier to amplify the signal from the host device; and transmit the amplified signal to the antenna; and first, second, and third switches to: when the first and second switches are closed and the third switch is open, couple the first amplifier to the second amplifier in a parallel structure; and when the first and second switches are open and the third switch is closed, couple the first amplifier to the second amplifier in a stacked structure.

A multiple-mode RF power amplifier includes two power amplifiers, output combiner circuitry, and a switchable impedance circuit. The power amplifiers receive first and second input RF signals and produce first and second amplified RF signals. The output combiner circuitry combines the amplified RF signals to produce a combined amplified RF signal. The switchable impedance circuit has an input terminal coupled to an isolated port of the output combiner circuitry. When the switchable impedance circuit is in a first state, the isolated port is coupled through the switchable impedance circuit to a first impedance to configure the multiple-mode RF power amplifier as a balanced amplifier. When the switchable impedance circuit is in a second or third state, the isolated port is coupled through the switchable impedance circuit to a second or third impedance to configure the multiple-mode RF power amplifier as a first or second type of Doherty power amplifier.

Apparatuses, systems and methods for operating a power amplifier are described. A controller can drive a power amplifier chain with first input bias voltages to operate the power amplifier chain in a first operation mode that implements a Doherty amplifier. The controller can drive the power amplifier chain with second input bias voltages to operate the power amplifier chain in a second operation mode that implements a balanced amplifier. The controller can tune the termination circuit in accordance with an operation mode of the power amplifier chain.

A Doherty amplifier including: a first transistor for main amplifier having a source-to-drain parasitic capacitance and operating in class AB; a transmission line whose input end is connected to an output end of the first transistor and whose output end is connected to a composite point; a second transistor for auxiliary amplifier having a source-to-drain parasitic capacitance and operating in class C; a series capacitor whose input end is connected to an output end of the second transistor and whose output end is connected to the composite point, and to reduce the capacitance value of impedance seen from the composite point toward the output end of the second transistor at the time of a backoff operation; and an output matching circuit connected between the composite point and a point of connection to an output load, to match the impedance of the composite point to the impedance of the output load.

An amplifier module includes a module substrate with a mounting surface, and a thermal dissipation structure that extends through the module substrate. A ground contact of a power transistor die is coupled to a surface of the thermal dissipation structure. Encapsulant material covers the mounting surface of the module substrate and the power transistor die, and a surface of the encapsulant material defines a contact surface of the amplifier module. A ground terminal is embedded within the encapsulant material. The ground terminal has a proximal end coupled to the thermal dissipation structure, and a distal end exposed at the contact surface. The ground terminal is electrically coupled to the ground contact of the power transistor die through the thermal dissipation structure.

An integrated circuit is disclosed comprising at least one first field effect transistor, having at least one first source contact and at least one first drain contact and at least one first gate contact, and at least one second field effect transistor, having at least one second source contact and at least one second drain contact and at least one second gate contact, wherein the first drain contact is connected to the second drain contact, and the first source contact is coupled to the second gate contact, wherein the first source contact, the first drain contact, the first gate contact, the second source contact, the second drain contact and the second gate contact are implemented as structured metallization layers on a single substrate, and the first and second drain contacts share at least one single dedicated surface area on said substrate.