Thesis for a degree 【 display / non-display 】

Thesis for a degree 【 display / non-display 】

• The development and characterisation of a parameterised RSFQ cell library for layout synthesis

  Lieze Schindler

  Stellenbosch University   2021.3

  Doctoral Thesis   Single Work    [Reviewed]

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  Other Link： https://scholar.sun.ac.za/handle/10019.1/109815

Papers 【 display / non-display 】

Papers 【 display / non-display 】

• Application of Phase-Based Circuit Theory to RSFQ Logic Design

  Lieze Schindler; Coenrad J. Fourie

  IEEE Transactions on Applied Superconductivity   32 ( 3 )   2022.4  [Reviewed]

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  Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE   Single Work  

  In contrast to transistor-based semiconductor circuits, there is currently no widely accepted formalized circuit theory or design methodology for superconductor rapid single flux quantum (RSFQ) logic circuits. Experienced designers intuitively consider flux loops, nodal phase, and branch currents when making design choices, but the lack of a formalized design process makes it difficult for inexperienced RSFQ circuit designers to construct a functioning logic cell without a reference. This results in new circuit designers, mostly recycling templates from published circuit designs without fully understanding why the circuits function as they do. Inexperienced RSFQ circuit designers often follow an iterative process where cell parameter values are adjusted, and the cell is run through electronic simulation engines until the desired functionality is reached. We propose the development of a formalized circuit design theory for RSFQ logic from first principles using phase-based circuit analysis. The circuit is designed using dc analysis to establish the dc operating point of the circuit. Phase-based analysis and simulation are then used to verify the dynamic circuit functionality. To demonstrate this method, we discuss examples for well-known RSFQ cells. We analyze the initial operating margins of these designs and discuss design accuracy and efficiency. Methods for current regulation to minimize current leakage between cells are discussed. We also present how this design methodology can be used to design new circuits such as an RSFQ XNOR cell. We investigate how an inverting (NOT) cell can be combined with other logic cells to minimize cell latency.

  Other Link： https://ieeexplore.ieee.org/document/9681154

• The ColdFlux RSFQ Cell Library for MIT-LL SFQ5ee Fabrication Process

  Lieze Schindler; Johannes A. Delport; Coenrad J. Fourie

  IEEE Transactions on Applied Superconductivity   32 ( 2 )   2022.3  [Reviewed]

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  Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE   Joint Work  

  The ColdFlux project, within the IARPA SuperTools program, aims to develop an open-source EDA tool suite for superconductor circuits, with focus on Rapid single flux quantum (RSFQ) and Adiabatic quantum-flux-parametron (AQFP) logic. The functionality of the ColdFlux tool suite is validated through the development of ready-to-use cell libraries. The process of establishing the open-source ColdFlux RSFQ cell library is documented, along with the set of EDA tools developed within the project required for each step. This includes the initial cell design using phase-based equations, circuit simulation, operating margin analysis, and cell parameter optimization. The row-based layout architecture for the RSFQ cell library is also presented. Several of the designed RSFQ cells are placed within test circuits and fabricated through the MIT-LL SFQ5ee fabrication process. We present the measured results for these test circuits and discuss design efficiency, potential improvements, and future work.

  Other Link： https://ieeexplore.ieee.org/document/9653858

• Adopting a Standard Track Routing Architecture for Next-Generation Hybrid AC/DC-Biased Logic Circuits

  L. Schindler, C. L. Ayala, K. Jackman, C. J. Fourie and N. Yoshikawa

  IEEE Transactions on Applied Superconductivity   33 ( 5 )   2023.8  [Reviewed]

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  Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Single Work  

• Design and Characterization of Track Routing Architecture for RSFQ and AQFP Circuits in a Multilayer Process

  Coenrad Johann Fourie; Christopher Lawrence Ayala; Lieze Schindler; Tomoyuki Tanaka; Nobuyuki Yoshi … Show more authors

  IEEE Transactions on Applied Superconductivity   30 ( 6 )   2020.9  [Reviewed]

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  Language：English   Publishing type：Research paper (scientific journal)   Joint Work  

  Other Link： https://ieeexplore.ieee.org/document/9072514

• Impedance Matching of Passive Transmission Line Receivers to Improve Reflections Between RSFQ Logic Cells

  Lieze Schindler; Paul le Roux; Coenrad J. Fourie

  IEEE Transactions on Applied Superconductivity   30 ( 2 )   2020.3  [Reviewed]

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  Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE   Single Work  

  Devices used for rapid single flux quantum (RSFQ) cell interconnects include passive transmission lines (PTLs) and Josephson transmission lines. In this article, we demonstrate software analysis methods with which reflections on PTLs can be improved through impedance matching without compromising the margins of the connected RSFQ logic cells. RSFQ cells are typically designed to connect to PTL transmitters and receivers before attaching the PTL interconnects. These transmitters and receivers are used as matching and buffer stages between the cell and the PTL; and can be adjusted to minimize impedance mismatching. We integrate PTL transmitters and receivers within the RSFQ cell to decrease the amount of Josephson junctions required to incorporate PTL interconnect functionality. Frequency domain analysis on each cell provides equivalent impedance characteristics used for impedance matching.

  Other Link： https://ieeexplore.ieee.org/document/8951137

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Presentations 【 display / non-display 】

Presentations 【 display / non-display 】

• Cell design methodology and circuit theory of RSFQ logic

  Lieze Schindler

  European Conference on Applied Superconductivity (EUCAS)  2019.9 

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  Event date： 2019.9

  Language：English   Presentation type：Oral presentation (general)  

  Venue：Glasgow, UK  

• Standard cell layout synthesis for row-based placement and routing of RSFQ and AQFP logic families

  Lieze Schindler

  International Superconductive Electronics Conference (ISEC)  2019.8  IEEE-CSC

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  Event date： 2019.7 - 2019.8

  Language：English   Presentation type：Oral presentation (general)  

  Venue：Riverside, CA, USA  

• Moat Design and Analysis for AQFP Circuits

  Lieze Schindler

  East Asia Symposium on Superconductor Electronics 

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  Event date： 2023.3

  Language：English   Presentation type：Oral presentation (general)  

• Adopting a Standard Track Routing Architecture for Next-Generation Hybrid AC/DC-Biased Logic Circuits

  Lieze Schindler

  Applied Superconductivity Conference (ASC) 

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  Event date： 2022.10

  Language：English   Presentation type：Poster presentation  

• Adopting a standard track routing architecture for next-generation hybrid ac/dc-biased logic circuits

  Lieze Schinder

  JSPS 146th Committee International Symposium on Superconductor Electronics 

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  Event date： 2022.9

  Language：English   Presentation type：Poster presentation  

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