A radio frequency circuit includes a first acoustic wave filter that is connected to a common terminal and includes a first acoustic wave resonator, a first LC filter that is connected to the common terminal via the first acoustic wave filter and includes at least one of an inductor or a capacitor, a second acoustic wave filter that is connected to the common terminal and includes a second acoustic wave resonator, and a second LC filter that is connected to the common terminal via the second acoustic wave filter and includes at least one of an inductor or a capacitor.

A power amplifier includes a distributor distributing an input first signal to a second signal and a third signal delayed by about 2 degrees (45<<90) from the second signal, a first amplifier amplifying the second signal and outputting a fourth signal when a first-signal power level is not lower than a first level, a second amplifier amplifying the third signal and outputting a fifth signal when the first-signal power level is not lower than a second level that is greater than the first level, a first phase shifter receiving the fourth signal and outputting a sixth signal delayed by about degrees from the fourth signal, a second phase shifter receiving the fifth signal and outputting a seventh signal advanced by about degrees from the fifth signal, and a combiner combining the sixth and seventh signals and outputting an amplified signal of the first signal.

A radio frequency (RF) power transistor circuit includes a power transistor and at least one decoupling circuit. The power transistor has a control electrode coupled to an input terminal for receiving an RF input signal, and a current electrode for providing an RF output signal at an output terminal. A decoupling circuit is coupled between the control electrode and a ground terminal, and/or between the current electrode and the ground terminal. The decoupling circuit includes a resistor coupled in series with components of a resonant circuit having a resonance that is lower than an RF frequency (e.g., lower than 20 megahertz). The resistor is for dampening the resonance of the resonant circuit.

A system includes an input port having an input voltage, an output port having an output voltage, and a power converter having a switch network with a plurality of power switches and a first resonant tank having a first resonant capacitor and a first resonant inductor, where at least one resonant component within the first resonant capacitor and the first resonant inductor is a switchable component configured to switch between different values. The system further includes a resonant mode selection block configured to adjust a value of the switchable component to maintain a performance of the system, and a controller configured to adjust a switching frequency or a duty cycle of the power converter.

A multiple-stage amplifier includes a driver stage die and a final stage die. The driver stage die includes a first type of semiconductor substrate (e.g., a silicon substrate), a first transistor, and an integrated portion of an interstage impedance matching circuit. A control terminal of the first transistor is electrically coupled to an RF signal input terminal of the driver stage die, and the integrated portion of the interstage impedance matching circuit is electrically coupled between a current-carrying terminal of the first transistor and an RF signal output terminal of the driver stage die. The second die includes a III-V semiconductor substrate (e.g., a GaN substrate) and a second transistor. A connection, which is a non-integrated portion of the interstage impedance matching circuit, is electrically coupled between the RF signal output terminal of the driver stage die and an RF signal input terminal of the final stage die.

Bias circuits and methods for silicon-based amplifier architectures that are tolerant of supply and bias voltage variations, bias current variations, and transistor stack height, and compensate for poor output resistance characteristics. Embodiments include power amplifiers and low-noise amplifiers that utilize a cascode reference circuit to bias the final stages of a cascode amplifier under the control of a closed loop bias control circuit. The closed loop bias control circuit ensures that the current in the cascode reference circuit is approximately equal to a selected multiple of a known current value by adjusting the gate bias voltage to the final stage of the cascode amplifier. The final current through the cascode amplifier is a multiple of the current in the cascode reference circuit, based on a device scaling factor representing the relative sizes of the transistor devices in the cascode amplifier and in the cascode reference circuit.

A power amplifier module includes an amplifier that amplifies an input signal and outputs the amplified signal, a harmonic termination circuit that is disposed subsequent to the amplifier and that attenuates a harmonic component of the amplified signal, the harmonic termination circuit including at least one field effect transistor (FET), and a control circuit that controls a gate voltage of the at least one FET to adjust a capacitance value of a parasitic capacitance of the at least one FET. The control circuit adjusts the capacitance value of the parasitic capacitance of the at least one FET, and thereby a resonance frequency of the harmonic termination circuit is adjusted.

Embodiments of RF amplifiers and RF amplifier devices include a transistor, a multiple-section bandpass filter circuit, and a harmonic termination circuit. The bandpass filter circuit includes a first connection node coupled to the amplifier input, a first inductive element coupled between the first connection node and a ground reference node, a first capacitance coupled between the first connection node and a second connection node, a second capacitance coupled between the second connection node and the ground reference node, and a second inductive element coupled between the second connection node and the transistor input. The harmonic termination circuit includes a third inductive element and a third capacitance connected in series between the transistor input and the ground reference node. The harmonic termination circuit resonates at a harmonic frequency of a fundamental frequency of operation of the RF amplifier.

A Wilkinson Combiner circuit is disclosed. The circuit includes first and second input ports, and a resistive-capacitive (RC) network coupled there between. The circuit further includes an amplifier having an amplifier input node, and a coupled inductor. The coupled inductor includes first, second, and third terminals, coupled to the first input port, the second input port, and the amplifier input node, respectively. Signals conveyed from the first and second input ports are passed through the corresponding portions of the coupled inductor, are combined into a composite signal and amplified by the amplifier.

A Wilkinson Combiner circuit is disclosed. The circuit includes first and second input ports, and a resistive-capacitive (RC) network coupled there between. The circuit further includes an amplifier having an amplifier input node, and a coupled inductor. The coupled inductor includes first, second, and third terminals, coupled to the first input port, the second input port, and the amplifier input node, respectively. Signals conveyed from the first and second input ports are passed through the corresponding portions of the coupled inductor, are combined into a composite signal and amplified by the amplifier.