Abstract: A parallel analog to digital converter which uses a dual-rank arrangement of flash converters. The flash converters have Josephson junctions and act as a sample and hold circuit. The dual-rank arrangement allows a smaller number of comparators to be used than in a pure parallel conversion scheme, which also makes encoding the outputs of the flash converters less complex. The analog to digital converter includes an encoder which controls its output interferometers based on the net flux generated by combinations of input currents into the encoder.

Abstract: A flexible transfer line for delivering coolant from a storage dewar to cool superconducting circuitry is provided with a delivery capillary coupled to the storage dewar, this capillary being thermally isolated from ambient temperatures. The transfer line has an outer flexible support coaxial with the delivery capillary, and an inner flexible shield between the delivery capillary and the outer flexible support. Heat in the shield is continuously removed to thereby provide the thermal isolation of the delivery capillary. The thermal isolation allows a low-flow rate of coolant through the delivery capillary since inefficiences due to thermal conduction and radiation are substantially eliminated.

Abstract: In a time domain reflectometer a first step generator may include two branches of elements which are current sensitive and will produce a gap voltage if the current exceeds a specific threshold. Each branch may include either Josephson junction devices or tunnel diodes. When a trigger signal plus a bias current exceed a threshold value a first one of the elements in a first branch produces a gap voltage and diverts current to the second branch. The current causes all of the elements in the second branch to produce gap voltages and the current is diverted back to the first branch to switch the states of the remaining elements of the first branch. Once all of the elements in both branches produce gap voltages, the total signal produced by these elements is transmitted to a third output branch. The circuit produces a fast step signal and lends itself to expansibility whereby the amplitude of the step signal can be varied by varying the number of elements in the branches of the circuit.

Abstract: A connector provides electrical and mechanical connection between the inner conductors of a pair of coaxial lines. The connector avoids the use of a slotted female conductor by either providing a slotted male conductor or by providing slotless conductors. The configuration allows a two layer construction of the connector so that the construction is simple and so that signals of higher frequency can be transmitted without severe signal degradation. In addition, the connector provides an electrical contact which is close to the interface between the two inner conductors so that the resonant frequency of the connector is sufficiently high as to avoid degradation of the electrical performance of the connector.

Abstract: Miniature soft probes are used to provide a high speed connection to circuits on a wafer. The probe contains a co-planar line on a soft substrate which provides a flexibility for secure contacts. A miniature coaxial line is directly connected to the coplanar line with a zero degree angle. This configuration makes the probe very small and result in high performance. A planar link between two ground planes eliminates any unwanted odd mode. The probes have high speed and wideband transmission lines with interfaces which have speed in the picoseconds and bandwidths in the hundreds of gigahertz. The probes have multi-functional capabilities, such as high impedance buffering and DC blocking, due to printed circuits which constitute a portion of the probe. The printed circuits are produced by a thin film photolithic process. These probes are best suited for on-wafer tests, diagnostics and measurements as well as interfacing on-wafer circuits with other electronic or electro-optical systems.

Abstract: A circuit is provided for sampling and accurately reproducing unknown signals which could be electrical, optical, x-ray, gamma ray or particle signals with picosecond resolution. The circuit comprises a superconductive sampling gate having at least two states which are distinguishable from one another and switching circuitry to switch the state of the sampling gate. The switching circuitry includes a sampling pulse source and a bias current source which are combined with the unknown signal to change the state of the monitor gate. A step generator utilizing Josephson junction technology is connected to the source of the unknown signal and sends a signal to the source of the unknown signal in order to initiate the outputting of the unknown signal and thus the sampling. Timing circuitry, also utilizing Josephson junction technology, provides an adjustable delay between the step signal generation and the sampling pulse generation.

Abstract: An ultrafast analog to digital converter is provided which uses Josephson devices. The converter has a plurality of Josephson junction interferometers. The output of each interferometer is a bit that forms part of a digital representation of a sampled analog signal. Each of the interferometers has an offset, with each offset being different. The bits output by the interferometers are weighted by the offsetting. The weighting of bits by offsetting rather than periodicity allows the use of interferometers which do not need to maintain periodicity over a great number of periods, and can therefore have lower internal inductance and better high speed properties.

Abstract: A circuit is provided for sampling and accurately reproducing unknown signals, which could be electrical, optical, X-ray, gamma ray or particle signals, with picosecond resolution. The circuit comprises a superconductive sampling gate having at least two states which are distinguishable from one another and switching circuitry to switch the state of the sampling gate. The switching circuitry includes a sampling pulse source and a bias current source which are combined with the unknown signal to change the state of the monitor gate. A step generator utilizing Josephson junction technology is connected to the source of the unknown signal and sends a signal to the source of the unknown signal in order to initiate the outputting of the unknown signal and thus the sampling. Timing circuitry, also utilizing Josephson junction technology, provides an adjustable delay between the step signal generation and the sampling pulse generation.