Results from the ColdFlux Superconductor Integrated Circuit Design Tool Project

In five and a half years, the ColdFlux project under the IARPA SuperTools program pushed the boundaries of understanding the requirements for and the actual capabilities of digital and analog superconductor electronic design automation (S-EDA) tools. The SuperTools program demanded significant beyond-state-of-the-art deliverables in four main areas: RTL synthesis, architectures, and verification; analog design and layout synthesis; physical design and test; and technology CAD and cell library design. Through the work of academic groups scattered over four continents, the ColdFlux effort forged into a powerful set of open-source and commercial S-EDA tools unlike any before, rivaled only by a commercial toolchain from Synopsys under the same SuperTools umbrella. We present an overview of the tools from where we started to the eventual project deliverables before showcasing some of the most significant progress-catalyzed by the project's demands-beyond the original program goals. These include powerful and fast simulation and extraction engines, magnetic field and flux trapping analysis, advanced clocking methods, multi-chip interface extraction and verification, superconductor multi-port S-parameter extraction, unified multi-layer design-rule compliant track blocks for automated place and route of both rapid single flux quantum (RSFQ) and adiabatic quantum-flux-parametron (AQFP) cells, models and tools for validation and test, multi-bit single flux quantum (SFQ) cell design and their usage in architecture innovations for full CPU designs and more. Comprehensive RSFQ and AQFP cell libraries and a process design kit (PDK) were developed with the ColdFlux tools as part of the project. The AQFP cell library features a logically rich collection of 80+ cells, including 3- and 5-input logic gates, signal-driving boosters, and refined RSFQ-to-AQFP interfaces, while the RSFQ library has 30+ cells. We also discuss the efforts to make the tools work over multiple operating systems, maintain and disseminate open-source code, and simplify compilation and installation. We include links to all the code repositories. Finally, we discuss how the full toolchain enables and enhances the superconductor IC design process.