A Conceptual Level Design Approach to Complex Systems

David B. Lidsky,  Ph.D. 1998 (advisors: Jan Rabaey, Paul Wright, Richard Newton)..

The complexity of electronic circuits has grown dramatically over the past several decades. Circuits with more than 1 million gates, combined with gigabit memories, clocked at 1000s of MHz are emerging. In addition, heterogeneity has become the norm, with analog, digital, and mixed-signal circuitry commonly included in the same design. Circuit design is further complicated by a number of new trends. For example migration toward sub-micron line widths necessitates that aspects of the design (e.g., subthreshold noise, inductive effects) need to be considered much earlier in the design process than previously necessary. System complexity is rapidly outgrowing current CAD tools ability to aid in design. An important aspect of the design process is to be able to evaluate and modify designs during the conception of a system. Furthermore, throughout the design process, it is necessary to be able to abstract key properties in order to analyze large, highly heterogeneous systems. The work in this thesis addresses the evaluation of increasingly complex systems both 1) at the crucial early stages of the design process when code and netlists have yet to be specified and 2) throughout the design process when design  specifications and tools are distributed amongst people, computer systems and physical locations. This thesis focuses on methodologies and tools for complex-system design. In particular, it formalizes the use of a higher level of abstraction, the conceptual-level, in the context of electronic systems. A prototype design system focused on conceptual-level design, PowerPlay, was created to demonstrate the requirements of a CAD tool for complex systems. The most important features of PowerPlay is the use of object-oriented macromodels and the creation and use of hyperlinked spreadsheets. Addressing the increasing size of design teams, PowerPlay was created to leverage off of the capabilities of the WWW. Hence a number of techniques for networked design are presented. The work concludes with a number of systems created with PowerPlay as part of the design flow and a roadmap for future WWW-based, complex-system CAD environments.