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.

Circuits, devices and methods related to multi-mode power amplifiers. A power amplifier (PA) assembly can include a radio-frequency (RF) amplification path having a first stage and a second stage, with each stage including a transistor. The PA assembly can further include a biasing circuit having a first bias path between a supply node and the base of a corresponding transistor. The PA assembly can further include a linearizing circuit implemented as either or both of a second bias path and a coupling path relative to the first bias path. The second bias path can be configured to provide an additional base bias current to the base under a selected condition. The coupling path can be configured to improve linearity of the corresponding transistor operating in a first mode while allowing a ballast resistance to be sufficiently robust for the corresponding transistor operating in a second mode.

Power amplifier bias circuit. A power amplifier bias circuit can include an emitter follower device and an emitter follower mirror device coupled to form a mirror configuration. The emitter follower device can be configured to provide a bias signal for a power amplifier at an output port. The power amplifier bias circuit can include a reference device configured to mirror an amplifying device of the power amplifier. The emitter follower mirror device can be configured to provide a mirror bias signal to the reference device.

Power amplifier bias circuit. A power amplifier bias circuit can include an emitter follower device and an emitter follower mirror device coupled to form a mirror configuration. The emitter follower device can be configured to provide a bias signal for a power amplifier at an output port. The power amplifier bias circuit can include a reference device configured to mirror an amplifying device of the power amplifier. The emitter follower mirror device can be configured to provide a mirror bias signal to the reference device.

A Doherty power amplifier includes a carrier amplifier, a peaking amplifier, and a peaking amplifier bias circuit coupled to the peaking amplifier and configured to provide a peaking amplifier bias signal to the peaking amplifier based on a saturation level of the carrier amplifier.

A Doherty power amplifier includes a carrier amplifier, a peaking amplifier, and a peaking amplifier bias circuit coupled to the peaking amplifier and configured to provide a peaking amplifier bias signal to the peaking amplifier based on a saturation level of the carrier amplifier.

A quasi-differential amplifier with an input port and an output port. The amplifier has a phase shifter network with a first port connected to the input port, a second port, and a third port. A first amplifier has an input connected to the second port of the phase shifter network, and an output, and a second amplifier has an input connected to the third port of the phase shifter network, and an output. A balun circuit includes a first differential port connected to an output of the first amplifier, a second differential port connected to an output of the second amplifier, and a single-ended port. An output matching network is connected to the single-ended port of the balun circuit and to the output port.

A quasi-differential amplifier with an input port and an output port. The amplifier has a phase shifter network with a first port connected to the input port, a second port, and a third port. A first amplifier has an input connected to the second port of the phase shifter network, and an output, and a second amplifier has an input connected to the third port of the phase shifter network, and an output. A balun circuit includes a first differential port connected to an output of the first amplifier, a second differential port connected to an output of the second amplifier, and a single-ended port. An output matching network is connected to the single-ended port of the balun circuit and to the output port.

An active device and circuits utilized therewith are disclosed. In an aspect, the active device comprises an n-type transistor having a drain, gate and bulk and a p-type transistor having a drain, gate and bulk. The n-type transistor and the p-type transistor include a common source. The device includes a first capacitor coupled between the gate of the n-type transistor and the gate of the p-type transistor, a second capacitor coupled between the drain of the n-type transistor and the drain of p-type transistor and a third capacitor coupled between the bulk of the n-type transistor and the bulk of p-type transistor. The active device has a high breakdown voltage, is memory less and traps even harmonic signals.

A power amplifier circuit includes N (N is an integer equal to or greater than 2) power amplifier circuit cores, which in operation, amplify power of an input signal, N inductors, which in operation, are connected to the N power amplifier circuit cores, and ring-oscillator-type transconductance (gm) generation circuitry, which in operation, generates transconductance (gm) for compensating power loss of the N inductors.