Wideband power combiners and splitters are provided herein. In certain embodiments, a power combiner/splitter is implemented with a first coil connecting a first port and a second port, and a second coil connecting a third port and a fourth port. The first coil and the second coil are inductively coupled to one another. For example, the first coil and the second coil can be formed using adjacent conductive layers of a semiconductor chip, an integrated passive device, or a laminate. The power combiner/splitter further includes a fifth port tapping a center of the first coil and a sixth port tapping a center of the second coil. The fifth port and the sixth port serve to connect capacitors and/or other impedance to the center of the coils to thereby provide wideband operation.

Apparatus and methods for oscillation suppression of cascode power amplifiers are provided herein. In certain implementations, a power amplifier system includes a cascode power amplifier including a plurality of transconductance devices that operate in combination with a plurality of cascode devices to amplify a radio frequency input signal. The power amplifier system further includes a bias circuit that biases the plurality of cascode devices with two or more bias voltages that are decoupled from one another at radio frequency to thereby inhibit the cascode power amplifier from oscillating.

A control circuit includes a first output unit configured to output a constant bias current for setting an electrical bias state of a bias circuit to the bias circuit; a second output unit configured to output a bias control current or constant voltage for controlling the electrical bias state of the bias circuit to the bias circuit; a resistor having one end connected to a reference potential; and a switch provided between another end of the resistor and an output terminal of the second output unit.

A radio frequency (RF) power combiner includes a first port with a first inverting input and a first non-inverting input, a second port with a second inverting input and a second non-inverting input, a first stabilization line coupled between the first non-inverting input and second non-inverting input, and a second stabilization line coupled between the first inverting input and the second inverting input.

A distributed power amplifier includes radio frequency (RF) input and output terminals. A first field effect transistor (FET) is coupled at a first gate terminal to the RF input terminal and at a first drain terminal to the RF output terminal. The first FET has a first periphery and a first source terminal electrically connected to ground potential. A second FET has a second periphery smaller than the first periphery. The second FET has a second gate terminal electrically coupled to the first gate terminal through a first inductor, a second drain terminal electrically coupled to the first drain terminal through a second inductor, and a second source terminal electrically connected to the ground potential. A drain voltage terminal, which excludes a resistive element, is electrically coupled to a drain bias network through which a drain bias voltage is applied to the first drain terminal and the second drain terminal.

A multistage power amplifier comprises a first amplification circuit which receives a first bias current; a second amplification circuit which receives a second bias current; an envelope detection circuit which outputs a direct current (DC) detection voltage based on an envelope of an input radio frequency (RF) signal; and a bias compensation circuit which compensates for the first bias current based on the second bias current in response to the DC detection voltage.

A loudspeaker power amplifier comprising a digital amplifier is provided. The amplifier has a negative input and a positive input as well as a negative output and a positive output. The power amplifier further comprises a first feedback circuit from the positive output to the negative input, and a second feedback circuit from the negative output to the positive input. The first and the second feedback circuit each have a first and a second amplification circuit.

A multi-voltage generation circuit and related envelope tracking (ET) amplifier apparatus is provided. In one aspect, a multi-voltage generation circuit is configured to generate a number of ET target voltages based on an analog voltage signal. In another aspect, a multi-amplifier ET circuit can be configured to include a number of amplifier circuits for amplifying concurrently a radio frequency (RF) signal based on a number of ET voltages. The multi-amplifier ET circuit also includes a number of driver circuits configured to generate the ET voltages base on a number of ET target voltages. In this regard, the multi-voltage generation circuit can be provided in the multi-amplifier ET circuit to generate the ET target voltages based on the analog voltage signal that corresponds to the RF signal. In examples discussed herein, the driver circuits are co-located with the amplifier circuits to help improve efficiency and maintain linearity in the amplifier circuits.

A particle accelerator system including a particle accelerator that accelerates charged particles, a signal source that outputs high frequency power for accelerating the charged particles in the particle accelerator, an amplifying unit that amplifies the high frequency power from the signal source, and supplies the high frequency power to the particle accelerator, the amplifying unit including a plurality of semiconductor amplifiers using a semiconductor, and a control unit that controls an operation of the amplifying unit. The control unit controls output of at least one of the plurality of semiconductor amplifiers.

The disclosure provides an amplifying apparatus including a plurality of amplifying circuits and an adjusting circuit. The input terminals of the amplifying circuits are coupled to a first common node. The output terminals of the amplifying circuits are coupled to a second common node. The adjusting circuit adjusts an input signal to generate an adjusted signal to the first common node; the adjusting circuit adjusts the signal of the second common node; or the adjusting circuit adjusts the input signal to generate the adjusted signal to the first common node and adjusts the signal of the second common node. The first control signal and the second control signal respectively control the amplifying circuits and the adjusting circuit to determine the gain, the linear power, and the output current of the amplifying apparatus.