A digital predistortion (DPD) system includes an input configured to receive an input signal. In some examples, a first signal path configured to generate a first signal based on the input signal. In some examples, an error model provider configured to generate an error model signal modeled after a gate bias error voltage associated with the DPD system. In some examples, a first combiner configured to combine the first signal and the error model signal to generate a first intermediate signal, and the DPD system generates an output signal based at least on the first intermediate signal.

A radio frequency amplifier includes a first input terminal, a second input terminal, an output terminal, and first and second amplifiers. The first amplifier includes a first amplifier input coupled to the first input terminal, and a first amplifier output. The second amplifier includes a second amplifier input coupled to the second input terminal, and a second amplifier output coupled to the output terminal by an output inductive element. An output combiner circuit is coupled between the first amplifier output and the second amplifier output. The output combiner circuit includes a first inductive element, a capacitor, and a second inductive element. The first inductive element is coupled between the first amplifier output and a first terminal of the capacitor, and the second inductive element is coupled between the second amplifier output and the first terminal of the capacitor. A second terminal of the capacitor is coupled to ground.

A Doherty amplifier is configured in such a way that a phase adjustment circuit adjusts either the phase of a return signal going to a first auxiliary amplification element as a result of passage of a first signal amplified by a second main amplification element through a second auxiliary amplification element as the return signal, or the phase of the return signal going to the second auxiliary amplification element as a result of reflection of the return signal by the first auxiliary amplification element, at a time of a backoff operation of the second auxiliary amplification element, in such a way that the sum of the phase of the return signal going to the first auxiliary amplification element and the phase of the return signal going to the second auxiliary amplification element is not equal to 0 degrees in the operating frequency band of the first signal.

A voltage dividing capacitor circuit includes first capacitor through third capacitor dividers and first through fourth load capacitors. The first capacitor divider includes a first flying capacitor and a plurality of first switches connected in series between a first voltage node and a ground node, and is connected to a second voltage node. The second capacitor divider is connected to the first voltage node, the second voltage node, and a first intermediate voltage node. The third capacitor divider is connected to the second voltage node, the ground voltage node, and a second intermediate voltage node. The first through fourth load capacitors are connected in series between the first voltage node and the ground node. The second capacitor divider includes a second flying capacitor and a plurality of second switches connected in series between the first voltage node and the second voltage node.

A radio frequency apparatus includes a power amplifier circuit, a signal coupling circuit, an extraction circuit, and a harmonic filter circuit. The power amplifier circuit is configured to amplify a differential signal to output a to-be-filtered signal. The signal coupling circuit includes a primary side inductor and a secondary side inductor. The signal coupling circuit is configured to convert the to-be-filtered signal received by the primary side inductor into a single-ended signal outputted from the secondary side inductor. The extraction circuit has a center tap. The extraction circuit is configured to inductively couple to the primary side inductor and output a common mode signal from the center tap. The harmonic filter circuit is configured to perform a harmonic filtering on the single-ended signal according to the common mode signal, such that the secondary side inductor of the signal coupling circuit outputs a filtered signal.

Aspects of the disclosure relate to a local oscillator frequency divider for a receiver or transmitter. In this regard a frequency divider has a first frequency input coupled to a first oscillator frequency output, a second frequency input coupled to a complementary second oscillator frequency output, a first in-phase/quadrature (I/Q) divided frequency output, and a complementary second I/Q divided frequency output. The frequency divider further has a first alternating current (AC) coupling capacitor between the first frequency input and the first oscillator frequency output and a second AC coupling capacitor between the second frequency input and the second oscillator frequency output.

A power amplifying circuit includes a first input terminal applied with a first bias voltage, a first amplifying circuit generating a first output signal and a second output signal according to an input signal and a first matching circuit combining the first output signal and the second output signal to generate an output signal. The first amplifying circuit includes a first transistor having a first electrode coupled to the first input terminal and a second electrode applied with a second bias voltage and a second transistor having a first electrode s coupled to the first input terminal and a second electrode applied with a third bias voltage. The first transistor generates the first output signal according to the first bias voltage and the second bias voltage. The second transistor generates the second output signal according to the first bias voltage and the third bias voltage.

A transceiver interface circuit, comprising a driver amplifier (DA), a load line impedance modulation circuit coupled to the DA; and multiple selectable output ports coupled to the load line impedance modulation circuit, an impedance presented by the load line impedance modulation circuit being adjustable dependent on at least a number of output ports coupled to the load line impedance modulation circuit.

Power amplifier supply networks with harmonic terminations are disclosed. In certain embodiments, a power amplifier system includes a first power amplifier that amplifies a first radio frequency (RF) signal of a first fundamental frequency, a second power amplifier that amplifies a second RF signal of a second fundamental frequency, and a power amplifier supply network that distributes a power amplifier supply voltage to the first power amplifier at a first distribution node and to the second power amplifier at a second distribution node. The power amplifier supply network includes a first harmonic termination circuit connected to the first distribution node that provide an open circuit at about twice the first fundamental frequency, and a second harmonic termination circuit connected to the second distribution node and that provides an open circuit at about twice the fundamental frequency.

A circuit module (e.g., an amplifier module) includes a module substrate, a thermal dissipation structure, a semiconductor die, encapsulant material, and an interposer. The module substrate has a mounting surface and a plurality of conductive pads at the mounting surface. The thermal dissipation structure extends through the module substrate, and a surface of the thermal dissipation structure is exposed at the mounting surface of the module substrate. The semiconductor die is coupled to the surface of the thermal dissipation structure. The encapsulant material covers the mounting surface of the module substrate and the semiconductor die, and a surface of the encapsulant material defines a contact surface of the circuit module. The interposer is embedded within the encapsulant material. The interposer includes a conductive terminal with a proximal end coupled to a conductive pad of the module substrate, and a distal end exposed at the contact surface of the circuit module.