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The results of waveform observations using the high-[T.sub.c] superconducting (HTS) sampler circuits with the commercial uni-travelling-carrier photodiode (UTC-PD) module and a custom-made integrated module is presented.

An output interface with a latching driver for single-flux-quantum (SFQ) circuits operating at 4.2 K is proposed. An optimum critical current density J(sub c) of the latching driver is discussed, and a multichip module (MCM) structure with SFQ circuits and latching drivers is proposed for 40-Gb/s operation.

A dc/SFQ converter, Josephson transmission lines (JTL) and a latching driver, formed using HTS junctions, are described and discussed.

A latching-type driver was developed using capacitively shunted high temperature superconductivity junctions.

We have fabricated a two-axis high-Tc planar gradiometer. Two gradiometers with planar gradiometric pickup coils lie diagonally on a square substrate. Therefore, they can measure field gradients, dBz/dx and dBz/dy at the same site. The two-axis gradiometer was fabricated on a 15 \times 15 mm MgO (100) substrate using an HTS multilayer process including crossovers, superconductive contacts and ramp-edge junctions. The width of the pickup coil and the baseline length are 6 mm and 8.5 mm, respectively. Voltage modulations in V-\Phi characteristics more than 20 \muV at 77 K were obtained for both the gradiometers. Parasitic effective areas measured by applying a uniform magnetic field were about 0.0001 mm^2. The gradiometer balance was estimated to be about 10^-2. The parasitic effective area was not due to the imbalance of the gradiometric pickup coil, but due to a sensitivity of SQUID itself. Flux noise level as low as 10 \mu\Phi0/Hz^{1/2} at frequencies down to 3 Hz and a cross-talk ratio less than 1/230 were obtained. [ABSTRACT FROM AUTHOR]

We developed a non-destructive testing (NOT) system utilizing multi-channel high-temperature superconductor (HTS) SQUID gradiometers in order to examine rare earth (RE)-123 coated conductors striated into multi-filamentary lines. The 5-channel HTS SQUID gradiometer array was composed of ramp-edge junctions with LaErBaCuO and SmBaCuO electrode layers, and fabricated by using an HTS multilayer fabrication technique. The parallel gradiometers detected the vertical element of magnetic field gradient induced around defects by an eddy current. It was demonstrated that we can detect macroscopic defects in each filamentary superconducting line at high speed up to 30 m/h. [ABSTRACT FROM AUTHOR]

We have fabricated high-temperature superconductor (HTS) dc superconducting quantum interference devices (SQUIDs) with a multilayer structure and ramp-edge Josephson junctions. For stable operation at 77 K, SmBa2 Cu3 Oy (SmBCO) and La0.1 - Er0.95Ba1.95Cu3Oy (La-ErBCO) films with a Tc above 90 K were employed as materials for the base-electrode and counter-electrode layers, respectively. Junctions were fabricated by employing a Cu-poor La-ErBCO layer as a precursor of the barrier. The fabricated parallel gradiometers with a baseline of 1-3 mm exhibited the field-induced modulation voltage of 20-50 μV at 77 K, and a clear modulation up to 86.8 K. Noise measurements at 77 K revealed a white flux noise of 4.5-10 μΦ0/Hz1/2 at 1 kHz. The magnetometer with an integrated 20-turn flux transformer and the effective area of about 1.8 mm2 exhibited a field noise of 25 fT/Hz1/2 or less at 1 kHz. [ABSTRACT FROM AUTHOR]

We have studied the effect of thermal noise and trigger jitter on the bandwidth of a high-Tc superconducting sampler by computer simulation and analytical calculation. Simulation results showed that the minimum IcRn product of the junctions required to obtain 100-GHz bandwidth is raised from 0.63 to 0.75 mV under the influence of the thermal noise at 40 K. On the other hand, the maximum trigger jitter for 100-GHz bandwidth is 1.87 ps when only an averaging effect is assumed. Considering both the effects of thermal noise and trigger jitter, we found, for example, that trigger jitter must be reduced down to 1 ps to realize the bandwidth above 100 GHz with an IcRn product of 1 mV at an operating temperature of 40 K. [ABSTRACT FROM AUTHOR]