In thk paper, the anafysis of GGAS MESFET distributed amplifiers and a systematic approach to their design are presented. The analysis focuses on fundamental design considerations and afso establishes the maximum gain-bandwidth product of the amplifier. The design approach presented enables one to examine the tradeoffs between the variables, such as the device, the number of devices, and the impedances and cutoff freqnency of the lines, and arrive at a design which gives the desired frequency response. Excellent agreement is shown when the theoretically predicted response of a typicaf amplifier is compared with computer-aided anafysis results, and good agreement is shown with previously published experimental results. 1.

Using various size rectangular mesas formed by photolithographically patterning and etching on single-crystal Bi2Sr2Ca1Cu2Ox superconductors, we have obtained c-axis volt-ampere characteristics as a function of magnetic field applied parallel to the a-b planes. Enhanced sensitivity with field perpendicular to the long side was observed even in mesas with dimensions smaller than the magnetic penetration depth λc. This can be explained in terms of viscous flow of Josephson vortices. The measurements are in good quantitative agreement with theoretical models for Josephson vortex motion in layered superconductors. Vortex flow coexists with the multiple hysteretic structure previously presented as evidence that this material behaves as a stack of underdamped intrinsic Josephson junctions.

We have investigated three-terminal single-layer thin-film superconducting devices made of YBaCuO and Nb. The devices incorporate regions of weak superconductivity in multiple parallel links that are influenced by current in a separate control line. These experiments were designed to study the possible application of this device as an rf amplifier. With the device biased, rf power was applied to the control line and the transmission coefficient, S21, was measured. The reverse transmission coefficient, S12, was also measured for comparison. Upon biasing into a flux flow state, the S21 of the device at rf frequencies was found to increase 10–15 dB over the zero bias value and over the reverse feed (S12 ) value. The device behaved linearly up to power inputs of +5 dBm (1-dB compression point). The bandwidth was limited only by the impedance transformer.

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