A distributed amplification device with p inputs, p outputs, p amplification paths comprises a redundant reservoir of n amplifiers including n-p back-up amplifiers, an input redundancy ring and an output redundancy ring formed by rotary switches, the input and output redundancy rings sharing the same technology. The internal amplification pathways associated with the n-p back-up amplifiers frame in an interlaced manner the internal amplification pathways associated with the p nominal amplifiers and the amplification paths of the routing configurations each pass through at least five rotary switches. The input and output redundancy rings are topologically and geometrically configured and the family of the routing configurations is chosen such that the electrical lengths of all the paths of one and the same routing configuration of the family are equal.

An amplifier circuit includes: plural transistors; plural first transmission lines respectively connected between input terminals of the plural transistors; plural second transmission lines respectively connected between output terminals of the plural transistors; an input node connected to the input terminal of a first stage transistor among the plural transistors; an output node connected to the output terminal of a final stage transistor among the plural transistors; and a capacitance connected to the output terminal of the first stage transistor via a third transmission line.

A technique relates to a qubit readout system. A cavity-qubit system has a qubit and a readout resonator and outputs a readout signal. A lossless superconducting circulator is configured to receive the microwave readout signal from the cavity-qubit system and transmit the microwave readout signal according to a rotation. A quantum limited directional amplifier amplifies the readout signal. A directional coupler is connected to and biases the amplifier to set a working point. A microwave bandpass filter transmits in a microwave frequency band by passing the readout signal while blocking electromagnetic radiation outside of the microwave frequency band. A low-loss infrared filter has a distributed Bragg reflector integrated into a transmission line. The low-loss filter is configured to block infrared electromagnetic radiation while passing the microwave readout signal. The low-loss infrared filter is connected to the microwave bandpass filter to receive input of the microwave readout signal.

A technique relates to a qubit readout system. A cavity-qubit system has a qubit and a readout resonator and outputs a readout signal. A lossless superconducting circulator is configured to receive the microwave readout signal from the cavity-qubit system and transmit the microwave readout signal according to a rotation. A quantum limited directional amplifier amplifies the readout signal. A directional coupler is connected to and biases the amplifier to set a working point. A microwave bandpass filter transmits in a microwave frequency band by passing the readout signal while blocking electromagnetic radiation outside of the microwave frequency band. A low-loss infrared filter has a distributed Bragg reflector integrated into a transmission line. The low-loss filter is configured to block infrared electromagnetic radiation while passing the microwave readout signal. The low-loss infrared filter is connected to the microwave bandpass filter to receive input of the microwave readout signal.

A distributed amplifier includes a plurality of transistors, a first line connecting gate electrodes of the transistors to each other, and a second line connecting drain electrodes of the transistors to each other, wherein the first line and the second line are electromagnetically coupled to each other at a position situated between immediately adjacent transistors among the plurality of transistors.

An amplifier with switchable and tunable harmonic terminations and a variable impedance matching network is presented. The amplifier can adapt to different modes and different frequency bands of operation by appropriate switching and/or tuning of the harmonic terminations and/or the variable impedance matching network.

A technique relates to a qubit readout system. A cavity-qubit system has a qubit and a readout resonator and outputs a readout signal. A lossless superconducting circulator is configured to receive the microwave readout signal from the cavity-qubit system and transmit the microwave readout signal according to a rotation. A quantum limited directional amplifier amplifies the readout signal. A directional coupler is connected to and biases the amplifier to set a working point. A microwave bandpass filter transmits in a microwave frequency band by passing the readout signal while blocking electromagnetic radiation outside of the microwave frequency band. A low-loss infrared filter has a distributed Bragg reflector integrated into a transmission line. The low-loss filter is configured to block infrared electromagnetic radiation while passing the microwave readout signal. The low-loss infrared filter is connected to the microwave bandpass filter to receive input of the microwave readout signal.

A distributed amplifier with improved stabilization includes an input transmission circuit, an output transmission circuit, at least one cascode amplifier coupled between said input and output transmission circuits. Each cascode amplifier includes a common-gate configured transistor coupled to the output transmission circuit, and a common-source configured transistor coupled between the input transmission circuit and the common-gate configured transistor. The distributed amplifier also includes a non-parasitic resistance and capacitance coupled in series between a drain and a gate of at least one of the common-gate configured transistors for increasing the amplifier stability.

An amplifier (100) adapted for noise suppression comprises a first input (102) for receiving a first input signal and a second input (104) for receiving a second input signal, the first and second input signals constituting a differential pair. A first output (106) delivers a first output signal and a second output (108) delivers a second output signal, the first and second output signals constituting a differential pair. A first transistor (M.sub.CG1) has a first drain (110) coupled to the first output (106) such that all signal current, except parasitic losses, flowing through the first drain (110) flows through the first output (106), and the first transistor (M.sub.CG1) further having a first source (112) coupled to the first input (102). A second transistor (M.sub.CS1) has a second gate (116) coupled to the first input (102), a second drain (118) coupled to the second output (108) such that all signal current, except parasitic losses, flowing through the second drain (118) flows through the second output (108), and the second transistor (M.sub.CS1) further having a second source (120) coupled to a first voltage rail (122). A third transistor (M.sub.CS2) has a third gate (124) coupled to the second input (104), a third drain (126) coupled to the first output (106) such that all signal current, except parasitic losses, flowing through the third drain (126) flows through the first output (106), and the third transistor (M.sub.CS2) further having a third source (128) coupled to the first voltage rail (122). A fourth transistor (M.sub.CG2) has a fourth drain (130) coupled to the second output (108) such that all signal current, except parasitic losses, flowing through the fourth drain (130) flows through the second output (108), and the fourth transistor (M.sub.CG2) further having a fourth source (132) coupled to the second input (104). A first load (Z.sub.L1) is coupled between the first output (106) and a second voltage rail (136). A second load (Z.sub.L2) is coupled between the second output (108) and the second voltage rail (136). A first inductive element (L.sub.1) is coupled between the first input (102) and a third voltage rail (138), and a second inductive element (L.sub.2) is coupled between the second input (104) and the third voltage rail (138). Transconductance of the first transistor (M.sub.CG1) is substantially equal to transconductance of the fourth transistor

An amplifier circuit includes: first and second nodes configured to receive input of differential signals; third and fourth nodes; a plurality of first inductors configured to be connected in series between the first and second nodes; a plurality of second inductors configured to be connected in series between the third and fourth nodes; a plurality of field effect transistors configured to have gates each configured to be connected between the plurality of first inductors, sources each configured to be connected to a reference potential node, and drains each configured to be connected between the plurality of second inductors; and a synthesizing unit configured to synthesize signals at the third and fourth nodes.