An RF amplifier includes an amplifier input, a transistor die with a transistor and a transistor input terminal, a fundamental frequency impedance matching circuit coupled between the amplifier input and the transistor input terminal, and a harmonic frequency termination circuit coupled between the transistor input terminal and a ground reference node. The harmonic frequency termination circuit includes a first inductance coupled between the transistor input terminal and a first node, and a tank circuit coupled between the first node and the ground reference node. The tank circuit includes a first capacitance coupled between the first node and the ground reference node, and a second inductance coupled between the first node and the ground reference node. The tank circuit is configured to shunt signal energy at or near a second harmonic frequency, while appearing as an open circuit to signal energy at a fundamental frequency of operation of the RF amplifier.

A power amplifier circuit includes an input-stage power amplifier configured to receive a radio-frequency input signal, an output-stage power amplifier configured to output an amplified radio-frequency output signal, and an intermediate-stage power amplifier disposed between the input-stage power amplifier and the output-stage power amplifier. The intermediate-stage power amplifier includes a first transistor, a second transistor, and a capacitor having a first end connected to an emitter of the first transistor and a second end connected to a collector of the second transistor. The intermediate-stage power amplifier receives a signal at a base of the second transistor thereof and outputs an amplified signal from a collector of the first transistor thereof.

An amplifier includes an input matching network; at least one transistor; an input lead coupled to the at least one transistor; a ground terminal coupled to the transistor; an output lead coupled to the at least one transistor; an output matching circuit coupled to the output lead and to the at least one transistor; and a baseband impedance enhancement circuit having at least one reactive element coupled to the input matching network. The baseband impedance enhancement circuit is configured to reduce resonances of a baseband termination.

An amplifier includes a semiconductor die and a substrate that is distinct from the semiconductor die. The semiconductor die includes a III-V semiconductor substrate, a first RF signal input terminal, a first RF signal output terminal, and a transistor (e.g., a GaN FET). The transistor has a control terminal electrically coupled to the first RF signal input terminal, and a current-carrying terminal electrically coupled to the first RF signal output terminal. The substrate includes a second RF signal input terminal, a second RF signal output terminal, circuitry coupled between the second RF signal input terminal and the second RF signal output terminal, and an electrostatic discharge (ESD) protection circuit. The amplifier also includes a connection electrically coupled between the ESD protection circuit and the control terminal of the transistor. The substrate may be another semiconductor die (e.g., with a driver transistor and/or impedance matching circuitry) or an integrated passive device.

Amplifier circuits, radio communication circuits, radio communication devices, and methods provided in this disclosure provide an amplifier circuit. The amplifier circuit may include an amplifier configured to amplify an input signal to provide an output signal. The amplifier circuit may further include an amplifier stack including a first transistor coupled to the amplifier. The amplifier stack may be configured to receive the output signal to amplify the output signal. The amplifier stack may be configured to receive an input control signal to control the first transistor based on an envelope of the input signal.

Methods and devices used in mobile receiver front end to support multiple paths and multiple frequency bands are described. The presented devices and methods provide benefits of scalability, frequency band agility, as well as size reduction by using one low noise amplifier per simultaneous outputs. Based on the disclosed teachings, variable gain amplification of multiband signals is also presented.

A harmonic processing circuit includes a first inductor having a first end connected to a connection line connected between an amplifier and an impedance matching circuit, and a second end connected to a first node, a first transmission line having a third end connected to the first node and a fourth end connected to a second node, and a parallel resonant circuit having a fifth end connected to the second node and a sixth end connected to a reference potential, wherein a second inductor and a first capacitor are connected in parallel between the fifth end and the sixth end, wherein when the first inductor is viewed from the connection line, an impedance at a frequency of a fundamental wave amplified by the amplifier is larger than an impedance at a frequency of a second harmonic having twice the frequency of the fundamental wave.

A radio frequency power amplifier with harmonic control circuit as well as method for manufacturing the same are disclosed. According to an embodiment, a radio frequency power amplifier includes: a planar dielectric substrate, a first conductive layer and a second conducting layer. The first conductive layer is disposed on a first side of the planar dielectric substrate. The second conducting layer is disposed on a second side of the planar dielectric substrate. The first conductive layer has a pattern comprising one or more harmonic control circuits. The second conductive layer acts as a ground plane. The second side of the planar dielectric substrate is opposite to the first side of the planar dielectric substrate.

Disclosed herein are signal amplifiers having a plurality of amplifier cores. Individual amplifier cores can be designed to enhance particular advantages while reducing other disadvantages. The signal amplifier can then switch between amplifier cores in a particular gain mode to achieve desired performance characteristics (e.g., improving noise figure or linearity). Examples of signal amplifiers disclosed herein include amplifier architectures with a low noise figure amplifier core that reduces the noise figure and a linearity boost amplifier core that increases linearity. The disclosed signal amplifiers can switch between a first active core and a second active core for a single or particular gain mode to achieve desired signal characteristics during different time periods.

A device for controlling wireless charging output power based on a PWM integrating circuit includes a magnetic-resonance transmitting module and a magnetic-resonance receiving module. The magnetic-resonance transmitting module includes a wireless charging base, a Bluetooth master circuit, a DC/DC regulator circuit, a PWM integrating circuit, a radio-frequency power amplifier source, a radio-frequency current sampling circuit and a magnetic-resonance transmitting antenna. Both the radio-frequency power amplifier source and the magnetic-resonance transmitting antenna are mounted at the wireless charging base. The magnetic-resonance transmitting antenna is connected to the magnetic-resonance receiving module. The magnetic-resonance receiving module includes a cooling fin, a magnetic-resonance receiving antenna, a Bluetooth slave circuit, a receiving rectifier and regulator circuit and a charging control circuit. The magnetic-resonance receiving antenna, the receiving rectifier and regulator circuit and the charging control circuit are connected successively. The magnetic-resonance receiving antenna is arranged directly above the magnetic-resonance transmitting antenna.