A current control circuit controls a bias current that is supplied to an amplifier transistor that amplifies a radio-frequency signal and includes a node, a constant current source circuit that supplies a first current to the node, and a variable current source circuit that supplies a second current to the node, based on a result of comparison between a potential of the node and a reference potential. The node outputs a control current including the first current and the second current for controlling the bias current.

An amplifier including a P-channel transistor having current terminals coupled between a first node and a second node and having a control terminal coupled to a third node receiving an input voltage, an N-channel transistor having current terminals coupled between a fourth node developing an output voltage and a supply voltage reference and having a control terminal coupled to the second node, a first resistor coupled between the first node and a supply voltage, a second resistor coupled between the first and fourth nodes, and a current sink sinking current from the second node to the supply reference node. The amplifier may be converted to differential form for amplifying a differential input voltage. Current devices may be adjusted for common mode, and may be moved or added to improve headroom or to improve power supply rejection. Chopper circuits may be added to reduce 1/f noise.

A gallium nitride based monolithic microwave integrated circuit includes a substrate, a channel layer on the substrate and a barrier layer on the channel layer. A recess is provided in a top surface of the barrier layer. First gate, source and drain electrodes are provided on the barrier layer opposite the channel layer, with a bottom surface of the first gate electrode in direct contact with the barrier layer. Second gate, source and drain electrodes are also provided on the barrier layer opposite the channel layer. A gate insulating layer is provided in the recess in the barrier layer, and the second gate electrode is on the gate insulating layer opposite the barrier layer and extending into the recess. The first gate, source and drain electrodes comprise the electrodes of a depletion mode transistor, and the second gate, source and drain electrodes comprise the electrodes of an enhancement mode transistor.

An amplifier including a P-channel transistor having current terminals coupled between a first node and a second node and having a control terminal coupled to a third node receiving an input voltage, an N-channel transistor having current terminals coupled between a fourth node developing an output voltage and a supply voltage reference and having a control terminal coupled to the second node, a first resistor coupled between the first node and a supply voltage, a second resistor coupled between the first and fourth nodes, and a current sink sinking current from the second node to the supply reference node. The amplifier may be converted to differential form for amplifying a differential input voltage. Current devices may be adjusted for common mode, and may be moved or added to improve headroom or to improve power supply rejection. Chopper circuits may be added to reduce 1/f noise.

This disclosure relates generally to the field of wireless communication infrastructure, and more particularly to a method, apparatus and system for envelope tracking. The system for envelope tracking comprising: a transistor; an RF transistor; a driver; a switcher current source; and a subtracting network; wherein the system is configured such that when an envelope voltage is less than a predetermined voltage value, the RF transistor is configured for decreasing an amount of absorbed biasing current, and when the envelope voltage is greater than a predetermined voltage value, the RF transistor is configured for increasing an amount of absorbed biasing current. The goal of RF transistor sinking is to absorb the redundant biasing current generated by the envelope tracking supply modulator to eliminate distortions.

A transmission module includes n oscillator modules and a phase command signal generator. Each of the oscillator modules includes a voltage controlled oscillator and an amplification circuit. The voltage controlled oscillators output transmission high-frequency signals having the same frequency and synchronized among the n oscillator modules by synchronous control based on a common reference signal. The amplification circuits each perform power amplification for the transmission high-frequency signal from a corresponding one of the voltage controlled oscillators and output the resultant signal. Phases of the transmission high-frequency signals synchronized among the n oscillator modules and output from the voltage controlled oscillators are separately controlled according to respective n phase command signals from the phase command signal generator.

pHEMT-based circuits and methods of improving the linearity thereof. One example pHEMT circuit includes a pHEMT connected between an input terminal and a load and a non-linear resistance connected to the pHEMT. The pHEMT produces a first harmonic signal at the load responsive to being driven by an input signal of a fundamental frequency received at the input terminal, the first harmonic signal having a first phase. The non-linear resistance has a resistance selected to produce a second harmonic signal at the load having a second phase opposite to the first phase. Methods can include determining a first amplitude and a first phase of a first harmonic signal produced at the load by a pHEMT in an ON state, and tuning the non-linear resistance to produce at the load a second harmonic signal having a second amplitude and a second phase that minimizes a net harmonic signal at the load.

Power amplification system is disclosed. A power amplification system can include a Class-E push-pull amplifier including a transformer balun. The power amplification can further include a reactance compensation circuit coupled to the transformer balun. In some embodiments, the reactance compensation circuit is configured to reduce variation over frequency of a fundamental load impedance of the power amplification system.

Circuits, methods and devices are disclosed, related to fast turn-on of radio-frequency (RF) amplifiers. In some embodiments, an RF amplifier circuit includes an amplification path implemented to amplify an RF signal, where the amplification path includes a switch and an amplifier. In some embodiments, each of the switch and the amplifier are configured to be ON or OFF to thereby enable or disable the amplification path, respectively. In some embodiments, the RF amplifier circuit includes a compensation circuit coupled to the amplifier, where the compensation circuit is configured to compensate for a slow transition of the amplifier between its ON and OFF states resulting from a signal applied to the switch.

A switch element includes a source having a plurality of source fingers and a drain having a plurality of drain fingers interleaved with the source fingers. An active mesa region is defined between at least one of the plurality of source fingers and an adjacent at least one of the plurality of drain fingers. A plurality of gates are disposed between the at least one of the plurality of source fingers and the adjacent at least one of the plurality of drain fingers. At least one of gates extends into the active mesa region from outside of the active mesa region and terminates within the active mesa region.