An amplification circuit includes a first amplifier provided between an input terminal and an output terminal and a second amplifier connected in parallel with the first amplifier between the input terminal and the output terminal. The first amplifier includes a transistor and a transistor, which are cascode connected with each other. The second amplifier includes a transistor. The transistor has a gate connected to the input terminal, a source connected to ground, and a drain. The transistor has a gate, a source connected to the drain of the transistor, and a drain connected to the output terminal. The transistor has a gate connected to the input terminal, a source connected to ground, and a drain connected to the output terminal.

A sound system includes a sound source having an analogue audio signal output and a sound volume control; signal amplifier apparatus (10) comprising an analogue signal input (12) configured to be coupled to the analogue audio signal output of the sound source, an analogue signal output (18) and an amplifier module (62) coupled between the signal input and the signal output. The amplifier module (62) has a fixed amplification gain within a range of 10 to 12 decibels. Control of the audio signal is effected solely by the sound volume control of the sound source. The amplifier module (64) also provides a fixed gain bass boost of 6 decibels. The system provides linear amplification and allows a user to reduce the volume of the sound source, which significantly reduces signal distortion. Volume control is at the sound source and not at the amplifier module, which optimises amplification quality and reduces the power requirement of the amplifier apparatus (10).

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.

Provided is a power amplifier circuit that reduces the effect of intermodulation distortion without necessarily increase in the circuit size. The power amplifier circuit includes a first amplifier that amplifies a first signal and output a second signal, an extraction circuit that extracts a second-harmonic wave included in the second signal, a phase adjustment circuit that adjusts the phase of the extracted second-harmonic wave, and a power combiner that combines the second-harmonic wave of the adjusted phase with a third signal and output the first signal.

A power amplifier is disclosed for amplifying an input signal and providing an amplified signal to a load at a junction node. The power amplifier comprises a splitter network, a carrier amplifier path and a peaking amplifier path. The peaking amplifier path comprises a first impedance transformer coupled between a peaking output matching network and the junction node to enhance the off-state impedance of the peaking amplifier. The carrier amplifier path comprises a second impedance transformer coupled between a carrier output matching network and the junction node.

A signal processing method and system includes a baseband signal baseband signal processing module configured to perform slow envelope processing on a first signal, to obtain an envelope value E(n) of the first signal on which the slow envelope processing has been performed, obtain a phase value θ(n) based on E(n), where θ(n) and E(n) are in a linear relationship, and separate the first signal into a second signal and a third signal based on θ(n), where a phase difference between the second signal and the third signal is 2 θ(n), an amplifier configured to amplify the second signal and the third signal, and a synthesizer is configured to combine the amplified second signal and third signal to obtain a fourth signal.

A first power amplifier amplifies first transmission signals in a first frequency band and outputs the resultant signals. A first matching circuit includes a plurality of first inductor portions and is connected to an output pad electrode of the first power amplifier. A second power amplifier amplifies second transmission signals in a second frequency band higher than the first frequency band and outputs the resultant signals. A second matching circuit includes at least one second inductor portion and is connected to an output side of the second power amplifier. A multilayer substrate has a first main surface and a second main surface located opposite to each other and is provided with the first and second power amplifiers and the first and second matching circuits. The first inductor portion closer than the other first inductor portions to the output pad electrode includes an inner-layer inductor portion located in the multilayer substrate.

A circuit and method for providing high-voltage radio-frequency (RF) energy to an instrument at multiple frequencies includes a plurality of inputs each configured to receive an RF voltage signal oscillating at a corresponding frequency, and a step-up circuit for generating magnified RF voltage signals based on the received RF voltage signals. The step-up circuit includes an LC network operable to isolate the RF voltage signals at the plurality inputs from one another while preserving a voltage magnification from each input to a common output at each of the corresponding frequencies.

A radio frequency module includes: a module board that includes a first principal surface and a second principal surface on opposite sides of the module board; a power amplifier configured to amplify a transmission signal; a first circuit component; and a power amplifier (PA) control circuit configured to control the power amplifier. The power amplifier and the PA control circuit are stacked on the first principal surface, and the first circuit component is disposed on the second principal surface.

A power amplifier circuit includes a first amplifier including two amplifiers connected in series with a matching circuit interposed therebetween, a first power supply circuit that supplies a first power supply voltage to a former amplifier of the first amplifier, and a second power supply circuit that supplies a second power supply voltage to a latter amplifier of the first amplifier.