A power amplifier comprises a first amplification stage having an input terminal receiving a radio frequency (RF) signal to be amplified and having a first coupling unit, a second amplification stage outputting an amplified radio frequency signal and having a second coupling unit and a third coupling unit providing RF feedback to the input terminal of the first amplification stage through an RF feedback path, the second coupling unit being coupled to the first coupling unit, and the third coupling unit being coupled to the first coupling unit.

An amplifier (T1) amplifies an input signal. A harmonic matching circuit (3) is connected to an output end of the amplifier (T1) via a first wire (W1). The harmonic matching circuit (3) includes a first inductor (L1) connected to the first wire (W1), a first capacitor (C1) connected in series to the first inductor (L1), a second inductor (L2) connected in parallel with the first inductor (L1), and a second capacitor (C2) connected in series to the second inductor (L2). The first inductor (L1) and the second inductor (L2) form a subtractive-polarity coupler which presents mutual inductance having subtractive polarity.

A high frequency circuit includes a transistor amplifying a high frequency signal, and having an input electrode and an output electrode, a line that is connected to any one of the input electrode and the output electrode, and transmits a high frequency signal or an amplified high frequency signal, a bias terminal to which a bias voltage is supplied, a bias circuit that has a first end connected to a first node and a second end connected to the bias terminal, and suppresses a high frequency signal having a frequency within an operating frequency band of the transistor from passing from the first node to the bias terminal, and a resonance circuit that is connected between a reference potential and a second node provided between the bias terminal and the bias circuit, and minimizes an impedance between the second node and the reference potential at a resonance frequency.

A radio frequency power amplifier and a device are disclosed. A first microstrip line and a second microstrip line are coupled, one end of the second microstrip line is an open stub and another end of the second microstrip line is grounded; and the first microstrip line having a first width is connected to a first transmission line having a second width which is wider than the first width. Therefore, some harmonic bands suppression can be implemented independently. Furthermore, the harmonic termination is independent and may not impact one or more fundamental components during matching a network. In addition, it may not take up more space and is sufficiently compact. Furthermore, sufficient wide harmonic response bandwidth can be provided.

A radio frequency power amplifier and a device are disclosed. A first microstrip line and a second microstrip line are coupled, one end of the second microstrip line is an open stub and another end of the second microstrip line is grounded; and the first microstrip line having a first width is connected to a first transmission line having a second width which is wider than the first width. Therefore, some harmonic bands suppression can be implemented independently. Furthermore, the harmonic termination is independent and may not impact one or more fundamental components during matching a network. In addition, it may not take up more space and is sufficiently compact. Furthermore, sufficient wide harmonic response bandwidth can be provided.

A high-efficiency amplifier is configured so that short stubs are provided in a line between a first substrate end and a second substrate end of a substrate, and among the short stubs, short stubs provided at locations other than both ends of the line include two short stubs and which are adjacent to each other, and which are provided at locations at which the two short stubs are to be electromagnetically coupled to each other.

A high-efficiency amplifier is configured so that short stubs are provided in a line between a first substrate end and a second substrate end of a substrate, and among the short stubs, short stubs provided at locations other than both ends of the line include two short stubs and which are adjacent to each other, and which are provided at locations at which the two short stubs are to be electromagnetically coupled to each other.

A system, in an active reflector device, adjusts a first amplification gain of each of a plurality of radio frequency (RF) signals received at a receiver front-end from a first equipment via a first radio path of an NLOS radio path. A first phase shift is performed on each of the plurality of RF signals with the adjusted first amplification gain. A combination of the plurality of first phase-shifted RF signals is split at a transmitter front-end. A second phase shift on each of the split first plurality of first phase-shifted RF signals is performed. The plurality of RF signals as a directed beam is transmitted to a second equipment via a second radio path of the NLOS radio path.

An amplifier that is configured to amplify an RF signal includes a power combiner circuit. The power combiner circuit includes a first branch connected between a first RF input port and a summing node and a second branch connected between a second RF input port and the summing node. Each of the first and second branches includes an impedance inverter. The Chireix combiner is configured to present a Chireix load modulated impedance response to the first and second RF input ports. The power combiner circuit further includes compensation elements being configured to at least partially compensate for a reactance of the Chireix combiner circuit in a Doherty amplifier mode in which a signal is applied to the first RF input port and the second RF input port is electrically open.

A directional coupler disclosed herein may include a main line provided on a substrate, the main line having a first end connected to an input port and a second end connected to an output port. The coupler may include a coupled line disposed on the substrate, the coupled line having a first end connected to a coupled port and a second end to an isolated port. The main line is electrically isolated from the coupled line. The coupled line includes multiple turns forming a winding, and a portion of the winding overlaps with the main line. The coupled line forms a plurality of windings inductively coupled with the main line. The main line and the coupled line are routed to propagate electric signals on both lines in a same direction, and enhance inductive coupling by mutual inductance.