An amplifier includes amplification stages connected in parallel between an input point and an output point and a feedback circuit, wherein the amplification stages each include a transistor configured to amplify a signal supplied from the input point, a harmonic processing unit configured to process harmonics present in an amplified signal output from an output node of the transistor, a connection point between the output node and the harmonic processing unit, and a transmission line connecting the connection point and the output point, wherein the feedback circuit feeds back a signal at the output point or a midway point of the transmission line of a given one of the amplification stages to a first end of a resistor connected to the connection point of the given one of the amplification stages, a second end of the resistor being connected to the connection point of another one of the amplification stages.

A Wilkinson power divider includes: -type LPFs connected to an input terminal; a T-type HPF having one end connected to one of the -type LPFs and having another end connected to a carrier amplifier; another T-type HPF having one end connected to another one of the -type LPFs and having another end connected to a /4 line; and an isolation resistor connected to connection points.

Embodiments of the present disclosure include a harmonic power amplifying circuit with high efficiency and high bandwidth and a radio-frequency power amplifier. The circuit comprises an input matching network (11), a transistor (M), and an output matching network (12); a gate of the transistor (M) connected to an output end of the input matching network (11), a drain thereof connected to an input end of the output matching network (12), and a source thereof being grounded; wherein the output matching network (12) enables a lower sideband of the harmonic power amplifying circuit to work in a continuous inverse F amplification mode and an upper sideband of the harmonic power amplifying circuit to work in a continuous F amplification mode; wherein the output matching network (12) and a parasitic network of the transistor (M) form a low pass filter. By transitioning from the continuous inverse F power amplifier working mode to the continuous F power amplifier working mode, the efficiency of a continuous harmonic control power amplifier is effectively improved to be higher than 60%, a relative bandwidth is improved to be higher than 80%, and the harmonic impedance is simple to match and easy to realize.

An RF amplifier includes an amplifier chip on a flange having an input and an output comprising a parasitic capacitance and a parasitic inductance, a first chip capacitor coupled to the output of the output of the amplifier by a first plurality of bond wires, and a second chip capacitor coupled to the first chip capacitor by a second plurality of bond wires, and an output impedance matching network having an input coupled to the output of the second chip capacitor by a third plurality of bond wires, and an output, and a phase shift between the input and the output of less than 90 degrees, wherein the phase shift from the output of the amplifier chip to the output of the output impedance matching network is 180 degrees.

An amplifier package may include a transistor, an output impedance matching circuit and one or more radial stub harmonic traps coupled to a control terminal of the transistor or to an output terminal of the transistor. The output impedance matching circuit and the radial stub harmonic traps may be formed on a single substrate or separate substrates, which may be formed from gallium nitride. Each radial stub harmonic trap may provide a low resistance path to ground for signal energy above a fundamental operating frequency of the amplifier, such as harmonic frequencies thereof.

An amplifier may include a transistor and input and output matching networks. One or more harmonic trap circuits may be electrically connected to a node located between the input matching network and a gate terminal of the transistor or to a node located between the output matching network and a drain terminal of the transistor. Each harmonic trap may provide a low resistance path to ground for signal energy above a fundamental operating frequency of the amplifier, such as harmonic frequencies thereof. The output matching network may act as an impedance inverter that provides a 90 degree insertion phase between the input of the output matching network and the load. A variable length drain feeder may connect a voltage source to an output of the output matching network.

A power amplifier includes a first amplifier configured to amplify a first high-frequency signal, a second amplifier configured to amplify a second high-frequency signal delayed with respect to the first high-frequency signal by at least 90 degrees, a hybrid coupler including a first transmission line and a second transmission line, a first power-supply circuit for the first amplifier, a second power-supply circuit for the second amplifier, and an output matching network. The hybrid coupler is connected to an output end of the first amplifier at a first end of the first transmission line. The first transmission line is connected to the first power-supply circuit and the output matching network at a second end. The second transmission line is connected to an output end of the second amplifier at a first end. The second transmission line is connected to the second power-supply circuit at a second end.

A Doherty amplifier including: a first transistor for main amplifier having a source-to-drain parasitic capacitance and operating in class AB; a transmission line whose input end is connected to an output end of the first transistor and whose output end is connected to a composite point; a second transistor for auxiliary amplifier having a source-to-drain parasitic capacitance and operating in class C; a series capacitor whose input end is connected to an output end of the second transistor and whose output end is connected to the composite point, and to reduce the capacitance value of impedance seen from the composite point toward the output end of the second transistor at the time of a backoff operation; and an output matching circuit connected between the composite point and a point of connection to an output load, to match the impedance of the composite point to the impedance of the output load.

Embodiments of radio frequency (RF) systems include a transmit/receive switch integrated with one or more power amplifiers and/or other components. The power amplifiers can have transformer-based architectures, and a power amplifier and switch can be integrated onto a single complementary metal oxide semiconductor die.

A cooler including a first surface on which a first high-frequency amplifier is installed in intimate contact therewith and a second surface which is opposite to the first surface and on which a second high-frequency amplifier is installed in intimate contact therewith. The first high-frequency amplifier amplifies a high-frequency signal and outputs an amplified high-frequency signal from an output terminal thereof. The second high-frequency amplifier amplifies a high-frequency signal and outputs an amplified high-frequency signal from an output terminal thereof. The cooler includes, on a third surface thereof, a first cooler terminal through which refrigerant flows into the cooler and a second cooler terminal through which the refrigerant flows out of the cooler. The third surface intersects the first surface and the second surface