An amplification circuit includes an input terminal, an output terminal, a capacitor, a bias unit, an amplification unit, and an impedance unit. The input terminal receives a radio frequency signal. The capacitor is coupled to the input terminal and the bias unit. The bias unit includes a transistor for controlling the bias current. The transistor has a first terminal for receiving a system voltage, and a control terminal coupled to the reference voltage terminal. The amplification unit has an input terminal coupled to the capacitor and the bias unit, and an output terminal coupled to the output terminal of the amplification circuit. The impedance unit has a first terminal coupled to the bias unit, and a second terminal coupled to the input terminal of the amplification circuit and the capacitor. The impedance unit adjusts the amplifying linearity of the amplification circuit according to a selection signal.

A display driver includes an operational amplifier, a D/A conversion circuit, a resistance circuit, and a resistance element. The D/A conversion circuit includes first and second variable resistance circuits including one end to which first and second voltages are input and another end connected to an inverting input node. The resistance circuit is provided between the inverting input node and an output node. The resistor is provided between the output node and the inverting input node. A resistance value of the first variable resistance circuit is set based on upper bit data of display data. A resistance value of the second variable resistance circuit is set based on lower bit data of the display data.

An acoustic wave device includes a high-acoustic-velocity film, a piezoelectric layer provided directly or indirectly on the high-acoustic-velocity film, an IDT electrode provided on the piezoelectric layer, and a dielectric film provided on the piezoelectric layer to cover the IDT electrode. An acoustic velocity of bulk waves propagating through the high-acoustic-velocity film is higher than an acoustic velocity of acoustic waves propagating through the piezoelectric layer. The dielectric film includes a material including hydrogen atoms.

A multiple-path (e.g., Doherty) amplifier includes a semiconductor die, a radio frequency (RF) signal input terminal, a combining node structure integrally formed with the semiconductor die, first and second amplifiers (e.g., main and peaking amplifiers, or vice versa) integrally formed with the semiconductor die, and a shunt circuit electrically connected between an output of the first amplifier and a ground reference node. Inputs of the first and second amplifier are electrically coupled to the RF signal input terminal, and outputs of the first and second amplifier are electrically coupled to the combining node structure. The shunt circuit includes a shunt inductance and a shunt capacitance coupled in series between the output of the first amplifier and the ground reference node, and the shunt capacitance has a first terminal coupled to the shunt inductance, and a second terminal coupled to the ground reference node.

A multistage amplifier includes: N amplifiers (N2), a (k+1).sup.th amplifier cascaded to a k.sup.th amplifier (1kN1), and each amplifier being configured to amplify a multicarrier signal; and an extraction circuit including an input and an output, the input being connected to an output of a j.sup.th amplifier (1jN1), and the output providing a compensation signal to an input of a (j+1).sup.th amplifier or an output of the (j+1).sup.th amplifier. The extraction circuit includes a filter circuit connected to the output of the j.sup.th amplifier that extracts a distortion frequency component of n times a differential frequency f2f1 (n1), a phase shifter cascaded to the filter circuit that shifts a phase of the component, and a gain adjustment circuit cascaded to the phase shifter that adjusts an amplitude of the component and generates the compensation signal.

A communication unit includes a plurality of parallel radio frequency, RF, signal paths. Located between a first RF signal path of the plurality of parallel RF signal paths comprising at least one first RF amplifier and a second signal path comprising at least one second RF amplifier is one of a shared inductor or shared transformer. The at least one first RF amplifier is coupled to a supply voltage via a first switch and at least one second RF amplifier is coupled to the supply voltage via a second switch, and the first switch is closed that provides the supply voltage to the at least one second RF amplifier whilst the second switch is opened.

A power amplifier system is disclosed. The power amplifier system includes a power amplifier having a first signal input and a first signal output and a main bias circuitry configured to provide a first portion of a first bias signal to the power amplifier through a first bias output coupled to the first signal input. Further included is peak bias circuitry that is configured to provide a second portion of the first bias signal to the power amplifier through a second bias output coupled to the first signal input, wherein the first portion of the first bias signal is greater than the second portion of the first bias signal over a first input power range and the second portion of the first bias signal is greater than the first portion of the first bias signal over a second input power range that is greater than the first input power range.

An apparatus has advanced amplifier Classes and low pass filter technologies for using software generated ascending or level waveforms that are effective when applying cardiac defibrillation and cardioversion waveforms which significantly reduce damage to the heart muscle. The apparatus comprises a waveform energy control system for delivering software generated waveforms comprising differentially driven Class D and Class B amplifier sections, wherein the Class D amplifier section produces Phase 1 ascending waveforms and has a programmable lowpass filter (LPF) and wherein the Class B amplifier section delivers hard-switched Phase 2 waveforms.

Disclosed in the present invention are a radio frequency power amplifier based on current detection feedback and a chip. The radio frequency power amplifier comprises multiple stages of amplifier circuits and at least one current detection feedback circuit; the input end of the current detection feedback circuit is connected to the input end of a current stage of amplifier circuit among the multiple stages of amplifier circuits by means of a corresponding resistor, and the output end of the current detection feedback circuit is connected to the input end of at least one stage of amplifier circuit prior to the current stage of amplifier circuit. The current detection feedback circuit generates, according to the detected quiescent operating current of the current stage of amplifier circuit, a control voltage varying inversely with the quiescent operating current, so that the current detection feedback circuit outputs current varying positively with the control voltage.

A power amplifier, a radio remote unit (RRU), and a base station, where the power amplifier includes an envelope controller, a main power amplifier, and an auxiliary power amplifier. The main power amplifier and the auxiliary power amplifier both set an envelope voltage output by the envelope modulator as operating voltages, and because the operating voltages of the main power amplifier and the auxiliary power amplifier may be adjusted simultaneously, symmetry of the power amplifier is improved, and an efficiency loss occurring probability is low, thereby enhancing efficiency of the power amplifier.