A broadband power amplifier circuit is disclosed for providing load modulation, and includes an active element for receiving an impedance matched signal and for amplifying the impedance matched signal to supply an amplified signal, and an output matching network having a load impedance and coupled to the active element for receiving the amplified signal, the output matching network matches the load impedance to an optimum load impedance of the active element.

A high-frequency power supply circuit includes an amplifier circuit. In the amplifier circuit, one end of an inductor is connected to a direct-current power supply. One end of a switching element is connected to the other end of the inductor. A parallel capacitor is connected in parallel to the switching element. One end of an LC series circuit is connected to the one end of the switching element. A circuit capacitor is connected between the other end of the LC series circuit and the other end of the switching element. The amplifier circuit amplifies a signal having a unique frequency input to a control terminal of the switching element. The amplifier circuit outputs, to a load, a current having the frequency from a connection point between the other end of the LC series circuit and the circuit capacitor.

Methods and circuital arrangements for turning OFF branches of a multi-branch cascode amplifier are presented. First and second switching arrangements coupled to a branch allow turning OFF the branch while protecting transistors of the branch from a supply voltage that may be greater than a tolerable voltage of the transistors. The first switching arrangement includes a transistor-based switch that is in series connection with the transistors of the branch. The first switching arrangement drops the supply voltage during the OFF state of the branch and provides a conduction path for a current through the branch during the ON state of the branch. A resistor and a shunting switch are coupled to a gate of the transistor-based switch to reduce parasitic coupling effects of the transistor-based switch upon an RF signal coupled to the branch during the ON state and OFF state of the branch.

A device for amplification of an input signal, the device comprising: amplification circuitry comprising a plurality of switchable transistors; a variable voltage input connected to the amplification circuitry; and controller circuitry; wherein the controller circuitry is configured to: set a target output power level of the device; and control at least one of: a state of connection between the plurality of switchable transistors to change an effective physical dimension of the amplification circuitry; or a level of the variable voltage input; in accordance with a load impedance of an output of the amplification circuitry, to amplify the input signal to the target output power level for that load impedance.

A power amplifier system is disclosed having a first amplifier with a high-power input and a high-power output. A second amplifier has a low-power input and a low-power output. A reconfigurable mode switch network has a first series switch branch coupled between the high-power output and an RF output, a first shunt branch is coupled between the RF output and a fixed voltage node, and a second series switch branch is coupled between the low-power output and a shared node of the first shunt branch. The shared node separates the first shunt branch into a first shared section that is between the RF output and the shared node and a second shared section that is between the shared node and the fixed voltage node.

Amplifiers with wide input range and low input capacitance are provided. In certain embodiments, an amplifier input stage includes a pair of input terminals, a pair of n-type input transistors, a first pair of isolation switches connected between the input terminals and the n-type input transistors, a pair of p-type input transistors, and a second pair of isolation switches connected between the input terminals and the p-type input transistors. The amplifier input stage further includes a control circuit that determines whether to use the n-type input transistors and/or the p-type input transistors for amplification based on a detected common-mode voltage of the input terminals. The control circuit opens the first pair of isolation switches to decouple the input terminals from the n-type input transistors when unused, and opens the second pair of isolation switches to decouple the input terminals from the p-type input transistors when unused.

Variable-phase amplifier circuits and devices. In some embodiments, an amplifier can include a variable-gain stage having a plurality of switchable amplification branches, with each being capable of being activated, such that a combination of one or more activated amplification branches provides respective gain level and phase shift. The plurality of switchable amplification branches can be configured such that the phase shift provided by each combination of one or more activated amplification branches compensates for a phase shift associated with the amplifier operating with the respective gain level of the variable-gain stage.

An amplifier circuit includes a first amplifier and a second amplifier. The first amplifier receives a first signal and generates a first amplification signal accordingly. The second amplifier receives a second signal and generates a second amplification signal accordingly. The first signal is related to a first frequency band, and the second signal is related to a second frequency band different from the first frequency band. When one of the first amplifier and the second amplifier is in use, the other one of the first amplifier and the second amplifier is unused. The first amplifier and second amplifier are coupled to a reference voltage terminal through a common node. The first amplifier includes a switch coupled between the common node and a stage of the first amplifier, and the switch can be controlled for reducing the loading effect caused by the first amplifier on the second amplifier.

A first branch group circuit includes a first branch circuit receiving a first RF input signal and first control information; and a second branch circuit receiving the first input signal and second control information. Each of the first and second branch circuits includes a power amplifier. The second control information enables the second branch circuit to be switched on or off while the first branch circuit remains on. A second branch group circuit includes: a third branch circuit receiving a second RF input signal and third control information; and a fourth branch circuit receiving the second input signal and fourth control information. Each of the third and fourth branch circuits includes a power amplifier. The fourth control information enables the fourth branch circuit to be switched on or off while the third branch circuit remains on. A combiner combines output signals of the power amplifiers to produce an output signal.

Radio frequency amplifiers with overload protection are provided herein. In certain configurations, an RF amplifier system includes an RF amplifier that receives an RF signal from an input terminal and that generates an amplified RF signal at an output terminal, and an overload detection circuit that generates a detection signal indicating a detected signal level of the RF amplifier. The RF amplifier includes an amplification device that amplifies the RF signal and a degeneration circuit that provides degeneration to the amplification device. Additionally, the detection signal is operable to control an amount of degeneration provided by the degeneration circuit so as to protect the RF amplifier from overload.