Modeling and Simulation of a Microstrip-SQUID Amplifier

TL;DR

This paper models a microstrip-SQUID amplifier using a lumped-circuit approach, analyzing how voltage gain and noise depend on parameters across different regimes, revealing a critical gain limit and noise effects.

Contribution

It introduces a simple lumped-circuit model to study the amplifier's gain and noise characteristics across various operational regimes.

Findings

Voltage gain cannot exceed a critical value that decreases with input power.

Spectrum of voltage gain is significantly affected by Johnson noise.

Gain behavior varies across linear, quasi-linear, and nonlinear regimes.

Abstract

Using a simple lumped-circuit model, we numerically study the dependence of the voltage gain and noise on the amplifier's parameters. Linear, quasi-linear, and nonlinear regimes are studied. We have shown that the voltage gain of the amplifier cannot exceed a characteristic critical value, which decreases with the increase of the input power. We have also shown that the spectrum of the voltage gain depends significantly on the level of the Johnson noise generated by the SQUID resistors.