A microwave amplifier including: a bias circuit that includes a line having an electrical length of one quarter the wavelength at the frequency configured to be amplified by the microwave amplifier and being connected between the output terminal of an amplifier and a bias voltage source, and a capacitor connected between a terminal where the line is connected to the bias voltage source and a ground that defines the reference potential of the microwave amplifier; and a resonant circuit that includes a resistor and a capacitor connected in series between the ground and the terminal where the line is connected to the bias voltage source.

Optimization methods via various circuital arrangements for amplifier with variable supply power are presented. In one embodiment, a switch can be controlled to include or exclude a feedback network in a feedback path to the amplifier to adjust a response of the amplifier dependent on a region of operation of the amplifier arrangement (e.g. linear region or compression region).

Optimization methods via various circuital arrangements for amplifier with variable supply power are presented. In one embodiment, a switch can be controlled to include or exclude a feedback network in a feedback path to the amplifier to adjust a response of the amplifier dependent on a region of operation of the amplifier arrangement (e.g. linear region or compression region).

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.

Systems and methods for controlling a power amplifier includes combining a digital modulated data signal with a digital bias signal to generate a combined digital signal, the digital bias signal generated based on an envelope for the modulated data signal; converting, by a digital-to-analog converter, the combined digital signal into a combined analog signal, the combined analog signal comprising an analog modulated data signal and an analog envelope bias signal; and separating the analog modulated data signal and the analog bias signal onto separate signal paths, wherein the converting is performed using a single digital-to-analog converter.

An output matching circuit includes: a converter electrically connected to an output end of a power amplifier element to convert an impedance of the output end to an impedance higher than the impedance of the output end by magnetic coupling; and a first filter circuit electrically connected between the output end of the power amplifier element and the converter to make a short circuit in a frequency band different from a predetermined transmission frequency band.

Power amplification system with adjustable common base bias. A power amplification system can include a cascode amplifier coupled to a radio-frequency input signal and coupled to a radio-frequency output. The power amplification system can further include a biasing component configured to apply one or more biasing signals to the cascode amplifier, the biasing component including a bias controller and one or more bias components. Each respective bias component may be coupled to a respective bias transistor.

Power amplification system with adjustable common base bias. A power amplification system can include a cascode amplifier coupled to a radio-frequency input signal and coupled to a radio-frequency output. The power amplification system can further include a biasing component configured to apply one or more biasing signals to the cascode amplifier, the biasing component including a bias controller and one or more bias components. Each respective bias component may be coupled to a respective bias transistor.

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.

Methods and apparatus to determine automated gain control parameters for an automated gain control protocol are disclosed. An example apparatus includes a first tuner to amplify an audio signal. Disclosed example apparatus also include a second tuner to amplify the audio signal. Disclosed example apparatus also include a first controller to tune the first tuner to apply a first gain representative of a first range of gains to the audio signal to determine a first amplified audio signal and tune the second tuner to apply a second gain representative a second range of gains to the audio signal to determine a second amplified audio signal, the second range of gains lower than the first range of gains. Disclosed example apparatus also include a second controller to select the first range of gains to be utilized in an automated gain control protocol when the first gain results in clipping of the first amplified audio signal and the second gain does not result in clipping of the second amplified audio signal.