A power amplifier module includes an amplifier transistor and a bias circuit. A first power supply voltage based on a first operation mode or a second power supply voltage based on a second operation mode is supplied to the amplifier transistor. The amplifier transistor receives a first signal and outputs a second signal obtained by amplifying the first signal. The bias circuit supplies a bias current to the amplifier transistor. The bias circuit includes first and second resistors and first and second transistors. The first transistor is connected in series with the first resistor and is turned ON by a first bias control voltage which is supplied when the first operation mode is used. The second transistor is connected in series with the second resistor and is turned ON by a second bias control voltage which is supplied when the second operation mode is used.

An electromagnetic wave radiator may include: a first metal layer; a plurality of metal side walls vertically protruding along an edge of the first metal layer; and a second metal layer suspended over the first metal layer. The second metal layer includes a plurality of ports radially extending from edges of the second metal layer and a plurality of slots penetrating the second metal layer in a radial direction.

A gallium nitride (GaN) power amplifier having a plurality of amplifier stages integrated into a monolithic integrated circuit is disclosed. The plurality of amplifier stages is coupled together between a radio frequency signal input and a radio frequency signal output, wherein at least one of the plurality of amplifier stages includes a first GaN transistor that is configured to have a first breakdown voltage that is no more than 75% of a second breakdown voltage of a second GaN transistor included in a different one of the plurality of amplifier stages.

A power amplifier circuit includes a power amplification circuit and a diode assembly. The diode assembly is connected in series with a transistor amplification circuit of the power amplification circuit, and the transistor amplification circuit is configured to, when load of power amplifier is mismatched, turn the diode assembly on, so as to divide current voltage to at least two electrodes of the transistor amplification circuit.

A power amplifier module includes a first amplifier that amplifies an input signal to generate a first amplified signal and outputs the first amplified signal, a second amplifier that amplifies the first amplified signal to generate a second amplified signal and outputs the second amplified signal, and a matching network disposed between an output terminal of the first amplifier and an input terminal of the second amplifier. The first amplifier is provided on a first chip, and the second amplifier is provided on a second chip. The matching network has an impedance transformation characteristic adjustable in accordance with a control signal.

Embodiments of a multiple-path amplifier (e.g., a Doherty amplifier) and a module housing the amplifier include a first amplifier (or first power transistor die) with a first output terminal, a second amplifier (or second power transistor die) with a second output terminal, and an impedance inverter line assembly electrically connected between the first and second output terminals. The impedance inverter line assembly includes a first transmission line and a surface mount component connected in series between the first and second output terminals. In various embodiments, the surface mount component is selected from a fixed-value capacitor, a fixed-value inductor, a tunable capacitor, a tunable inductor, and a tunable passive component network.

Temperature compensation circuits and methods for adjusting one or more circuit parameters of a power amplifier (PA) to maintain approximately constant Gain versus time during pulsed operation sufficient to substantially offset self-heating of the PA. Some embodiments compensate for PA Gain droop due to self-heating using a Sample and Hold (S&H) circuit. The S&H circuit samples and holds an initial temperature of the PA at commencement of a pulse. Thereafter, the S&H circuit generates a continuous measurement that corresponds to the temperature of the PA during the remainder of the pulse. A Gain Control signal is generated that is a function of the difference between the initial temperature and the operating temperature of the PA as the PA self-heats for the duration of the pulse. The Gain Control signal is applied to one or more adjustable or tunable circuits within a PA to offset the Gain droop of the PA.

In an example apparatus, a first transistor has a base terminal, a first current terminal and a second current terminal. The base terminal is coupled to an input voltage node. A second transistor has a control terminal, a third current terminal and a fourth current terminal. The third current terminal is coupled to the second current terminal. The fourth current terminal is coupled to a first resistor. A second resistor is coupled to the control terminal. An inductor is coupled between the first resistor and a ground terminal.

A radio-frequency power amplification circuit includes: a power amplification sub-circuit and an output matching sub-circuit, wherein the power amplification sub-circuit is used for selecting, according to a received control signal corresponding to a radio-frequency mode, a power amplification parameter corresponding to the radio-frequency mode to amplify a received radio-frequency signal, and outputting the amplified radio-frequency signal; the output matching sub-circuit is connected to the power amplification sub-circuit and is used for receiving the amplified radio-frequency signal, and transmitting, according to the control signal, the amplified radio-frequency signal by using an impedance corresponding to the radio-frequency mode.

A first stabilizing circuit (7a) is disposed between a first transistor (5a) and a first output matching circuit (10a) in a first stage. A second stabilizing circuit (7b) is disposed between a second transistor (5b) and a second output matching circuit (10b) in a second stage. The first stabilizing circuit (7a) includes a first band-pass filter and a first resistor (103a) connected in parallel. The first band-pass filter allows a signal of a frequency f1 lower than a central frequency fc of the operation frequencies as an amplifier to pass through. The second stabilizing circuit (7b) includes a second band-pass filter and a second resistor (103b) connected in parallel. The second band-pass filter allows a signal of a frequency f2 higher than the central frequency fc to pass through.