A power amplifier has a number n of power cells A.sub.i, a number n of output transmission lines TL.sub.1i for combining output powers from the power cells, and a number n of impedance transformation network ITN.sub.i, where i=1, . . . n. The number n of output transmission lines are connected in series. The output terminal of each power cells is connected to its output transmission line via its impedance transformation network. Each impedance transformation network is an upward impedance transformation network for transforming an output impedance of each power cell at the input terminal of the impedance transformation network into a higher impedance at the output terminal of the impedance transformation network. A number n of input transmission lines TL.sub.0i (i=1, 2 . . . n)=connected in series. The input terminal of the i-th power cell is connected to the second terminal of the i-th transmission line via a capacitor, where i=1, . . . n.

The present invention discloses an amplifier. The bias amplifier includes a signal input end, for inputting an input signal; a voltage input end, for inputting a source voltage; an amplifying circuit, for generating an amplified input signal according to the input signal, and the amplified input signal comprises a fundamental signal, a first harmonic signal and a second harmonic signal, wherein the first harmonic signal is a second order harmonic of the fundamental signal, and the second harmonic signal is a third order harmonic of the fundamental signal; a harmonic filter, coupled between the voltage input end and the amplifying circuit, for filtering the first harmonic signal and the second harmonic signal; and a signal output end, coupled to the harmonic filter, for outputting an output signal according to the amplified input signal.

The disclosure relates to a pre-5.sup.th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4.sup.th-Generation (4G) communication system, such as long term evolution (LTE). A transformer is provided. The transformer includes a first primary inductor, a second primary inductor, and a secondary inductor. The secondary inductor may be disposed between the first primary inductor and the second primary inductor. The secondary inductor may be disposed spaced apart from the first primary inductor and the second primary inductor.

Systems and apparatuses are disclosed that include an RF generator configured to generate RF signals having a wavelength. Amplifiers are configured to receive and amplify the RF signals from the RF generator and are separated from each other by a separation distance in a range between about 0.2 times the wavelength and about 10.0 times the wavelength. A power management system is configured to control one or more of the amplifiers based on information received that is associated with the RF signals.

Apparatus and methods for providing hot-switching immunity for radio frequency switching circuits are disclosed. A radio frequency switching circuit may include both a mechanical switch and a solid-state switch. The mechanical switch may be configurable to couple an output path of a power amplifier to a subsequent component in its transmission path when in a first mechanical switch state and to decouple the output path of the power amplifier from the subsequent component when in a second mechanical switch state. The solid-state switch may be configurable to operatively decouple the mechanical switch from a radio frequency power source when in a first solid-state switch state but not when in a second solid-state switch state. The solid-state switch may be in the first solid-state switch state during transitions of the mechanical switch between the first and second mechanical switch states.

An amplifier is formed in a wiring layer. A semiconductor device includes a second layer over a first layer with a metal oxide therebetween. The first layer includes a first transistor including a first semiconductor layer containing silicon. The second layer includes an impedance matching circuit, and the impedance matching circuit includes a second transistor including a second semiconductor layer containing gallium. The first transistor forms first coupling capacitance between the first transistor and the metal oxide, and the impedance matching circuit forms second coupling capacitance between the impedance matching circuit and the metal oxide. The impedance matching circuit is electrically connected to the metal oxide through the second coupling capacitance. The metal oxide inhibits the influence of first radiation noise emitted from the impedance matching circuit on the operation of the first transistor.

An amplifier is formed in a wiring layer. A semiconductor device includes a second layer over a first layer with a metal oxide therebetween. The first layer includes a first transistor including a first semiconductor layer containing silicon. The second layer includes an impedance matching circuit, and the impedance matching circuit includes a second transistor including a second semiconductor layer containing gallium. The first transistor forms first coupling capacitance between the first transistor and the metal oxide, and the impedance matching circuit forms second coupling capacitance between the impedance matching circuit and the metal oxide. The impedance matching circuit is electrically connected to the metal oxide through the second coupling capacitance. The metal oxide inhibits the influence of first radiation noise emitted from the impedance matching circuit on the operation of the first transistor.

Methods and apparatus are provided. In an example aspect, an amplifier protection circuit is provided. The amplifier protection circuit comprises an input for receiving a signal from a first amplifier, and an isolation circuit between the input and an output of the amplifier protection circuit. The isolation circuit is configured to sense a backward signal propagating from the output of the amplifier protection circuit towards the input to provide a sensed signal, and to provide at least one cancellation signal based on the sensed signal to at least partially cancel the backward signal.

A first primary line has a first node at one end and a third node at another end and transmits a radio-frequency signal between the first node and the third node. A second primary line has a second node at one end and a fourth node at another end and transmits a radio-frequency signal between the second node and the fourth node. A first secondary line has a portion connected to the second node and is electromagnetically coupled to the first primary line. The second secondary line has a portion connected to the first node and has another end connected to a portion of the first secondary line. The second secondary line is electromagnetically coupled to the second primary line. A first capacitor is connected in parallel to a portion of the second primary line or a portion of the second secondary line.

Disclosed is an electronic device comprising: a wireless communication circuit for generating an RF signal, an amplifier circuit electrically connected to the wireless communication circuit and configured to amplify the RF signal, and an antenna connected to the amplifier circuit. The amplifier circuit may comprise: a first amplifier; a second amplifier; a first transmission path connected to an output terminal of the first amplifier and the antenna; a second transmission path connected to an output terminal of the second amplifier and the first transmission path; a first variable impedance circuit located on the first transmission path and configured to change an electrical length of the first transmission path based on the frequency of the RF signal; and a second variable impedance circuit located on the second transmission path and configured to change the electrical length based on a power mode.