An embodiment is a distributed amplifier including amplifier blocks, each of the amplifier blocks including a first transmission line to receive input of a signal to an input end, a second transmission line to output a signal from an output end, a first termination resistor having a first end connected to a terminal end of the first transmission line, a second termination resistor having a first end connected to an input end of the second transmission line, and unit cells arranged along the first and second transmission lines, each of the unit cells having an input terminal connected to the first transmission line and an output terminal connected to the second transmission line, the amplifier blocks are connected in cascade such that a terminal end of the second transmission line of one of the amplifier blocks is connected to the first transmission line of a subsequent amplifier block.

Certain aspects of the present disclosure are directed to an amplifier. The amplifier may include a transistor coupled to an output of the amplifier, and a resonator coupled between the output of the amplifier and a reference potential node, a resonant frequency of the resonator being set to be at a subharmonic of a fundamental frequency of the amplifier, and an impedance of the resonator being greater than a load impedance of the amplifier at the fundamental frequency of the amplifier.

Certain aspects of the present disclosure are directed to an amplifier. The amplifier may include a transistor coupled to an output of the amplifier, and a resonator coupled between the output of the amplifier and a reference potential node, a resonant frequency of the resonator being set to be at a subharmonic of a fundamental frequency of the amplifier, and an impedance of the resonator being greater than a load impedance of the amplifier at the fundamental frequency of the amplifier.

A harmonic processing circuit includes: a feeder line configured to feed power to an amplifying device; and a harmonic processing unit connected to the feeder line, and configured to perform harmonic processing to a harmonic of a signal outputted from the amplifying device. The feeder line is connected to a fundamental wave matching circuit that is connected to the amplifying device and performs matching with respect to a fundamental wave of the signal.

An electromagnetic wave radiator may include: a first metal layer; a plurality of metal side walls vertically protruding along an edge of the first metal layer; and a second metal layer suspended over the first metal layer. The second metal layer includes a plurality of ports radially extending from edges of the second metal layer and a plurality of slots penetrating the second metal layer in a radial direction.

An electromagnetic wave radiator may include: a first metal layer; a plurality of metal side walls vertically protruding along an edge of the first metal layer; and a second metal layer suspended over the first metal layer. The second metal layer includes a plurality of ports radially extending from edges of the second metal layer and a plurality of slots penetrating the second metal layer in a radial direction.

An embodiment is a multiplexer including a first distributed amplifier with an impedance matched to 50Ω, the first distributed amplifier configured to receive a first signal and output a first amplified signal, a second distributed amplifier with an impedance matched to 50Ω, the second distributed amplifier configured to receive a second signal and output a second amplified signal, and a passive multiplexer configured to multiplex the first amplified signal and the second amplified signal, and output a multiplexed signal to a signal output terminal, the passive multiplexer including a first resistor having a first end to receive the first amplified signal, a second resistor having a first end to receive the second amplified signal, and a third resistor having a first end connected to second ends of the first and second resistors and a second end connected to the signal output terminal.

A method for isolating transmission lines of a radio frequency power amplifier and a transmission structure of the radio frequency power amplifier are provided. The method includes steps of setting a distance between adjacent two of transmission lines on a chip substrate to be greater than 2.5 times a width of each of the transmission lines, and disposing shielding lines at an inner side of each of the transmission lines and an outer side of each of the transmission lines opposite to the inner side; wrapping a permalloy layer on an outer wall of each of the transmission lines; and wrapping an aluminum layer on an outer wall of the permalloy layer, defining a plurality of grooves on an outer wall of the aluminum layer at intervals, where the plurality of the grooves are recessed inward and in an inverted triangular structure.

A method for isolating transmission lines of a radio frequency power amplifier and a transmission structure of the radio frequency power amplifier are provided. The method includes steps of setting a distance between adjacent two of transmission lines on a chip substrate to be greater than 2.5 times a width of each of the transmission lines, and disposing shielding lines at an inner side of each of the transmission lines and an outer side of each of the transmission lines opposite to the inner side; wrapping a permalloy layer on an outer wall of each of the transmission lines; and wrapping an aluminum layer on an outer wall of the permalloy layer, defining a plurality of grooves on an outer wall of the aluminum layer at intervals, where the plurality of the grooves are recessed inward and in an inverted triangular structure.

A distributed amplifier includes a first transmission line for input, a second transmission line for output, an input termination resistor connecting a line end of the first transmission line and a power supply voltage, an output termination resistor connecting an input end of the second transmission line and a ground, unit cells having input terminals connected to the first transmission line and output terminals connected to the second transmission line, and a bias tee configured to supply a bias voltage to an input transistor of each of the unit cells. An emitter or source resistor of the input transistor of each of the unit cells is set to a different resistance value from each other in order for a collector or drain current flowing through the input transistor of each of the unit cells to have a uniform value.