Microstrip superconducting quantum interference device amplifier: Conditional stability
D. Kinion, John L. Clarke
The scattering parameters of an amplifier based on a dc superconducting quantum interference device are directly measured at 4.2 K as functions of the bias current and applied magnetic flux. These parameters are used to determine the stability of the amplifier with arbitrary source and output load impedances. It was found that the amplifier is conditionally stable, and that the stability is improved by decreasing the gain or adding negative feedback. With suitable bias selection, the amplifier is shown to be sufficiently stable to allow operation with a resonant source impedance.
Applied Physics Letters•Apr 26, 2010•6 citations