An apparatus comprising a first circuit and a circuit. The first circuit may be configured to receive an input signal, split the input signal into component signals and present the component signals to a plurality of amplifiers. The second circuit may be configured to receive amplified component signals from the amplifiers and combine the amplified component signals into an output signal. The circuits may each comprise an outer conductor, an inner conductor, a cavity and a plurality of blades. Each of the blades may be arranged evenly spaced along a surface within the cavity and extend along a length of the surface with a shape. The shape of the blades may have a probe and the shape may gradually meet the surface and may be configured to provide a low-loss transition for propagation of a microwave signal. The output signal may be an amplified version of said input signal.

Amplifier circuitry is disclosed for receiving a differential signal and outputting a single-ended output signal. A travelling wave amplifier has a plurality of amplifier elements connected between an input transmission line and an output transmission line, each extending between first and second sides of the travelling wave amplifier. The input transmission line is configured to receive the first differential signal component at the first side and the output transmission line is configured to provide the single-ended output signal at the second side. A matched transmission line, which is configured to match at least some transmission properties of the input transmission line, receive the second differential signal component at the first end. A differential termination network is connected to both the input transmission line and matched and the matched transmission line and is configured to provide differential termination of signals received at the first and second termination inputs.

Amplifier circuitry is disclosed which has a travelling wave amplifier, with a plurality of amplifier elements connected between an input transmission line and an output transmission line, the transmission lines extending between first and second sides of the travelling wave amplifier. The input transmission line is configured to receive an input signal at the first side and the output transmission line is configured to output an output signal at the second side. The circuitry includes biasing circuitry for applying a DC bias to the output transmission line at at least one point upstream of a last amplifier element.

A traveling wave amplifier includes two input-side lines, two output-side lines, and amplification cells. The amplification cells each include a first input terminal, a second input terminal, a first transistor including a base connected to the first input terminal and a collector connected to one output-side line, a second transistor including a base connected to the second input terminal and a collector connected to the other output-side line, a current source connected to an emitter of each of the two transistors, a first series circuit connected between the collector of the second transistor and the base of the first transistor and including a capacitor and a resistor, and a second series of circuit connected between the collector of the first transistor and the base of the second transistor and including a capacitor and a resistor.

A distributed circuit includes: a first transmission line that has an input end to which an input signal is input; a second transmission line that has an output end from which an output signal is output; a plurality of unit cells that are disposed along the first and second transmission lines, the input terminals of the unit cells being connected to the first transmission line, the output terminals of the unit cells being connected to the second transmission line; two input termination resistors connected in parallel to an end of the first transmission line; and two output termination resistors connected in parallel to an end of the second transmission line. In the distributed circuit, at least one input termination resistor is a temperature-gradient resistor, and voltages at the two input termination resistors are changed symmetrically.

An amplifier circuit (200) for compensating an output signal provided at an output (212) of a circuit (210) is disclosed. The amplifier circuit (200) comprises an output transmission line (230) connected between the output (212) of the circuit (210) and an output port (240) and an amplifier (220). The amplifier (220) comprises multiple sub-amplifiers (221, 222, 223, 224), inputs of the multiple sub-amplifiers (221, 222, 223, 224) are coupled to an input transmission line (250) for receiving an error signal; and outputs of the multiple sub-amplifiers (221, 222, 223, 224) are coupled at respective places along the output transmission line (230) to inject a compensation signal to the output port (240). The error signal is derived from a reference input signal and the output signal of the circuit (210), and is amplified in the amplifier (220) into the compensation signal.

According to some aspects, a circuit is provided comprising a plurality of Josephson junctions arranged in series in a loop, at least one magnetic element producing magnetic flux through the loop, a plurality of superconducting resonators, each resonator coupled to the loop between a different neighboring pair of Josephson junctions of the plurality of Josephson junctions, a plurality of ports, each port coupled to at least one of the plurality of resonators at ends of the resonators opposite to ends at which the resonators are coupled to the loop, and at least one controller configured to provide input energy to each of the plurality of ports that causes the circuit to function as a circulator between the plurality of ports.

An amplifier circuit that includes a first amplifier that has a first input that receives an input signal, a second input and an output. The amplifier circuit also includes a second amplifier that has a first input that is coupled to the output of said the amplifier and a second input. The circuit further includes a first impedance network Z1, a second impedance network Z2, a third impedance network Z3 and a fourth impedance network Z4. The first impedance network Z1 is coupled to a load and the second input of the second amplifier, the second impedance Z2 is connected the output of the first amplifier and the second input of the first amplifier, the third impedance Z3 is connected to the output of the first amplifier and the load, the fourth impedance Z4 is connected the output of the second amplifier and the second input of said first amplifier.

A driver circuit includes a first termination resistor and a distributed amplifier comprising a plurality of pairs of input transistors and comprising inductors coupled between each pair of input transistors. The driver circuit also includes a distributed current-mode level shifter coupled to the first termination resistor. The distributed current-mode level shifter includes a first plurality of inductors coupled in series between the first termination resistor and the distributed amplifier and a first plurality of capacitive devices. Each capacitive device is coupled to a power supply node and to a node interconnecting two of the series-coupled inductors.

An amplifier arrangement comprises N amplifier stages comprising a main amplifier stage and a plurality of peaking amplifier stages. A transmission line comprises a varying impedance for transforming a load impedance to a higher impedance at the main amplifier stage, wherein the plurality of peaking amplifiers are coupled at intermediate locations to the transmission line. The amplifier arrangement is configured such that at least two of the peaking amplifiers are collectively driven with time delayed versions of substantially the same signal. The amplifier arrangement may be configured to operate with N2 or fewer transition points in a Doherty mode of operation. As such, the amplifier arrangement may comprise more amplifier stages than are necessarily required in a Doherty amplifier arrangement having the same number of transition points.