Experimental study of the RSFQ logic elements

The speed of Josephson circuits such as those required for Rapid Single Flux Quantum logic is limited by the Josephson plasma frequency, p , which (with few exceptions) increases monotonically with increasing critical current density, J c . Here we describe a new technique for directly measuring p , using the current-voltage characteristics of a simple structure based on externally-shunted, series-connected tunnel junctions. We present both experimental and theoretical demonstrations of the technique and describe its application to the determination of the junction capacitance, a property poorly characterized for high-J c junctions.

Section: Description Of Experimentsmentioning

confidence: 80%

“…1 using the PARTS process [3]. We measured I-V characteristics of JJs with a significant range of junction sizes (0.5-3 ), shunt resistances (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), and critical current densities (0. ).…”

Section: Description Of Experimentsmentioning

confidence: 99%

Direct Measurement of the Josephson Plasma Resonance Frequency From I-V Characteristics

Kleinsasser

Johnson

Delin

2005

“…The escape junctions J1 and J3 shield the SFQ pulse sources from the back reaction in the case of a double set or reset pulse. The pulse stretcher is based on the same concept but now a dc-squid containing junctions J5 and J6 is coupled to the flip-flop [7], [8]. When a signal is applied to the set input, the flip-flop switches to state 1 and the junction J6 is providing a finite dc voltage at the output.…”

Section: A Description Of the Pulse Stretcher Behaviormentioning

confidence: 99%

HTS Pulse-Stretcher and Second Order Modulator: Design and First Results

Roussy

Karthikeyan

Oomen

et al. 2005

Abstract-One of the remaining challenges in the application of superconducting electronics is the interfacing between superconducting and semiconducting environments. The voltage and speed mismatch between RSFQ pulses and semiconducting read-out electronics makes it necessary to amplify as well as stretch the RSFQ pulses. Moreover, circuits based on HTS (High Temperature Superconductor) technology are very attractive since they can operate under considerably relaxed cooling effort, which is one of the main problems with LTS (Low Temperature Superconductor) circuits.Within the European project SuperADC, a HTS second order sigma delta modulator and a pulse stretcher, used as an interface between the modulator and the first semi-conducting amplifier stage, have been designed at Twente University and will be presented here.Index Terms-HTS superconductors, Josephson junctions, rapid single flux quantum, superconducting/semiconducting interface circuits.

“…Now we have extended our experimental setup to evaluate basic RSFQ circuits. The circuit under test (CUT), we used throughout our experiment, was a chain consisting of a DC/SFQ converter, a Josephson transmission line (JTL), and an SFQ/DC converter [10]. Instead of the reduction of critical currents an alternative measure for the performance degradation of complex circuits has to be used, which we term error rate.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Effect of Flux Trapping on the Operation of RSFQ Circuits

Ebert

Ortlepp

Uhlmann

2009

This paper investigates the robustness of different ground plane configurations of superconducting circuits against magnetic flux trapping. The robustness of the circuit is determined by the change of the error rate at a specific operating point under the influence of an external magnetic field. A large number of thermocycles are used to determine the statistic properties of the error rate. The proposed measurement setup allows a fast scan of a two-dimensional operating area.