An amplifier includes an amplifying device and a bias circuit for providing a bias voltage for the amplifying device. The bias circuit is configured to provide the bias voltage in dependence of an output signal of an optical coupling arrangement which provides for electrical isolation.

The present disclosure relates to a kinetic inductance parametric amplifier that comprises an input port arranged to receive a pump tone, a DC bias and input signal; an output port arranged to provide an amplified version of the input signal; a tunable stepped-impedance assembly arranged to attenuate and/or filter predetermined frequency bands; and a high kinetic inductance line. The tunable stepped-impedance assembly is tuned at a frequency that allows for the amplifier to resonate at a predetermined frequency and a pump tone with a frequency higher than the input signal and a DC biasing signal to be transmitted to the high kinetic inductance line.

A current Iin is separated into currents I1 and I2. When I1 flows in a light emitting diode D1, the diode D1 emits light and the current path of a phototransistor Q1 becomes conductive. At that time, current Iout flows in a light emitting diode D2. When the diode D2 emits light, the current path of a phototransistor Q2 becomes conductive, and I2 flows. If the value of the current Iout is large, the light emitting strength of the diode D2 is large. A large current I2 flows in the phototransistor Q2, which decreases the value of the current I1 flowing in the diode D1. As a result, the light emitting strength of the diode D1 becomes small, and the value of the current Iout decreases. In this manner, since a photocoupler P2 functions as a negative feedback circuit, linearity of the current Iin and the current Iout improves.

An isolation amplifier includes an input circuit at high voltage potential with an input for a measurement signal to be transmitted, an input circuit configuration providing a coupling section signal representing the measurement signal, and a high-voltage-side control unit for driving the input circuit, a galvanically isolating coupling section for the potential-free transmission of the coupling section signal to an output circuit at low-voltage potential with an output circuit configuration for generating an output signal from the transmitted coupling section signal, an output for the output signal and at least one low-voltage-side control unit for generating control signals, input elements for inputting control commands and/or parameters into the high-voltage-side control unit, a low-voltage-side arrangement of all the input elements provided for the parameterization of the high-voltage-side control unit, exclusively in a low-voltage circuit, and a galvanically isolating control channel for transmitting the parameters for driving the input circuit.