Aspects of the disclosure include a power amplifier comprising an input to receive an input signal, an output to provide an amplified output signal, a balun coupled between the input and the output, at least one capacitor coupled to the balun, and a controllable load coupled to the at least one capacitor.

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.

Monolithic microwave integrated circuits (MMICs) tolerant to electrical overstress are provided. In certain embodiments, a MMIC includes a signal pad that receives a radio frequency (RF) signal, and an RF circuit coupled to the RF signal pad. The RF circuit includes a transistor layout, an input field-effect transistor (FET) implemented using a first portion of a plurality of gate fingers of the transistor layout, and an embedded protection device electrically connected between a gate and a source of the input FET and implemented using a second portion of the plurality of gate fingers. The MMIC is tolerant to electrical overstress events, such as field-induced charged-device model (FICDM) events.

An active balun circuit includes first and second transistors having emitters electrically coupled to each other and configured to output differential signals and a circuit element coupled between the connection point of the emitter of the first transistor and the emitter of the second transistor and a reference potential. The impedance of the circuit element at a particular frequency of the input signal appears significantly larger than impedances at other frequencies. An input signal from an input terminal is inputted to the base of the first transistor. The reference potential is applied to the base of the second transistor. A supply voltage is applied to the collector of the first transistor and the collector of the second transistor. A signal from the collector of the first transistor and a signal from the collector of the second transistor are outputted as the differential signals.

Apparatus and methods for load modulated power amplifiers are provided. In certain embodiments, a load modulated power amplifier system includes a power amplifier that receives a radio frequency signal at an input and provides an amplified radio frequency signal at an output, and a controllable load impedance coupled to the output of the power amplifier. The controllable load impedance receives an envelope signal that changes in relation to an envelope of the radio frequency signal, and the envelope signal is operable to control an impedance of the controllable load impedance to modulate a load at the output of the power amplifier.

Apparatus and methods for reconfigurable power amplifiers are disclosed. In certain embodiments, a mobile device includes a transceiver configured to generate a first radio frequency signal of a first frequency band and a second radio frequency signal of a second frequency band, and a front-end system including a push-pull power amplifier configured to selectively amplify one of the first radio frequency signal or the second radio frequency signal based on a band control signal. The push-pull power amplifier includes an input balun, an output balun, and a pair of amplifiers coupled between the input balun and the output balun. The band control signal is operable to control an output capacitance of the pair of amplifiers.

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.

Low noise amplifiers (LNAs) are disclosed herein. In certain embodiments, an LNA includes an input balun configured to convert a single-ended radio frequency (RF) receive signal to a differential RF receive signal, an amplifier chain configured to amplify the differential RF receive signal to generate a differential amplified RF receive signal, and an output balun configured to convert the differential amplified RF receive signal into a single-ended amplified RF receive signal. The LNA's amplifier chain is operable in multiple gain modes, and includes a first differential amplification stage, a second differential amplification stage, and a third differential amplification stage.

The radio-frequency differential circuit includes an input balun, an output balun, a first differential amplifying circuit, a second differential amplifying circuit, a first linear feedback circuit and a second linear feedback circuit; the first differential amplifying circuit is arranged between a first output end of the input balun and a first input end of the output balun; the second differential amplifying circuit is arranged between a second output end of the input balun and a second input end of the output balun; a first end of the first linear feedback circuit is connected with the input balun, a second end of the first linear feedback circuit is connected with the first differential amplifying circuit; a first end of the second linear feedback circuit is connected with the input balun, and a second end of the second linear feedback circuit is connected with the second differential amplifying circuit.

Disclosed is an ultra-high frequency amplifier which includes a first conductor connected to an amplifier input terminal to receive an RF signal applied to the amplifier input terminal, a second conductor parallel to a first portion of the first conductor, a third conductor separated from the second conductor and parallel to a second portion of the first conductor, and a transistor including a gate terminal connected to one end of the second conductor, a first terminal connected to one end of the third conductor, and a second terminal connected to an amplifier output terminal, wherein the first conductor and the second conductor form a first balun to output a first balance signal based on the RF signal, the first conductor and the third conductor form a second balun to output a second balance signal based on the RF signal.