A power amplifier includes an active device and an output matching circuit operably connected with the active device. The output matching circuit includes a bandpass impedance transformer, in particular, a multimode bandpass impedance transformer. The multimode bandpass impedance transformer may include a multimode resonator and coupling feed lines.

Apparatus and methods for bias switching of power amplifiers are provided herein. In certain configurations, a power amplifier system includes a power amplifier that provides amplification to a radio frequency (RF) signal and a bias control circuit that biases the power amplifier. The power amplifier includes an amplification transistor that receives the RF signal at an input, and a first bias network and a second bias network each connected to the input. The bias control circuit includes a first switch, a first reference current source that provides the first reference current to the first bias network through the first switch, a second switch, and a second reference current source that provides the second reference current to the second bias network through the second switch.

Methods and devices addressing design of wideband LNAs with gain modes are disclosed. The disclosed teachings can be used to reconfigure RF receiver front-end to operate in various applications imposing stringent and conflicting requirements. Wideband and narrowband input and output matching with gain modes using a combination of the same hardware and a switching network are also disclosed. The described methods and devices also address carrier aggregation requirements and provide solutions that can be used both in single-mode and split-mode operations.

In certain aspects, a chip includes a pad, and a power amplifier having a first output and a second output. The chip also includes a transformer, wherein the transformer includes a first inductor coupled between a first terminal and a second terminal of the transformer, wherein the first terminal is coupled to the first output of the power amplifier, and the second terminal is coupled to the second output of the power amplifier. The transformer also includes a second inductor coupled between a third terminal and a fourth terminal of the transformer, wherein the third terminal is coupled to the pad. The chip also includes a first switch coupled to the fourth terminal, a shunt inductor coupled in parallel with the first switch, and a low-noise amplifier coupled to the third terminal.

A power amplifier system is disclosed having a first stage amplifier that includes a first supply terminal, a first input, and a first output. A second stage amplifier has a second supply terminal, a second input, and a second output. A first stage bias circuitry has a bias output coupled to a bias input of the first stage amplifier and a bias control input. Absolute maximum ratings protection circuitry has a voltage monitoring input coupled to the second supply terminal and a bias control output coupled to the bias control input, wherein the absolute maximum ratings protection circuitry is configured to reduce the bias of the first stage amplifier through the bias control output based upon voltage monitored at the voltage monitoring input exceeding a predetermined voltage level. Additional absolute maximum ratings protection circuitry reduces the bias of the first stage amplifier if first stage amplifier supply voltage is excessive.

The present disclosure provides methods for manufacturing Doherty power amplifiers. The methods include: providing at least one main amplifier operated at a fundamental frequency; providing at least one peaking amplifier connected to the main amplifier in parallel and sharing a common load or a load; and connecting a first hybrid integrated matching circuit between output terminals of the at least one main amplifier and the at least one peaking amplifier. Connecting the first hybrid integrated matching circuit includes connecting a first circuit between the output terminals of the at least one main amplifier and the at least one peaking amplifier. The first circuit contributes as a part of an impedance inverting network of the first hybrid integrated matching circuit of the Doherty power amplifier.

A high frequency circuit includes a transmit terminal and a transmit and receive terminal, a power amplifier that amplifies a high frequency signal inputted from the transmit terminal and outputs the high frequency signal toward the transmit and receive terminal, and an output matching circuit that is positioned on a signal path connecting the power amplifier and the transmit and receive terminal and that optimizes the output load impedance of the power amplifier. The output matching circuit includes a matching circuit coupled to an output terminal of the power amplifier, another matching circuit, and a switch that changes a connection between the matching circuits. The power amplifier and the switch are formed at a single semiconductor IC. The matching circuits are formed outside the semiconductor IC.

An electromagnetic wave radiator may include: a first metal layer; a plurality of metal side walls vertically protruding along an edge of the first metal layer; and a second metal layer suspended over the first metal layer. The second metal layer includes a plurality of ports radially extending from edges of the second metal layer and a plurality of slots penetrating the second metal layer in a radial direction.

A power amplifier circuit includes a differential amplifier circuit configured to amplify a radio-frequency signal, a transformer disposed on an output side with respect to the differential amplifier circuit and including a primary winding and a secondary winding, and a dispersion circuit coupled to a midpoint of the primary winding of the transformer and configured to operate as an adjustment circuit. The dispersion circuit is configured to adjust, based on a supply voltage controlled in accordance with the envelope of the radio-frequency signal, a bias (bias current or bias voltage) to be supplied to the differential amplifier circuit.

An amplification circuit includes: an amplifier including a transistor that is connected between an input terminal and an output terminal; an input matching network that is connected between the input terminal and an input side of the amplifier and converts an impedance from a low impedance to a high impedance; a limiter circuit that is connected between a node between the input matching network and the input side of the amplifier, and ground and includes two diodes connected in opposite directions to each other; and a capacitor that is connected in series with the limiter circuit between the node and ground.