Logic Design for Array-Based Circuits

by Donnamaie E. White

Copyright © 1996, 2001, 2002 Donnamaie E. White



Last Edit July 22, 2001

Demand And Supply

The number of designers who can successfully complete the design of an array-based circuit through design submission and prototype acceptance is limited. Some estimates as of 1998 are as low as 50,000 engineers in the USA. The demand for array-based circuit designers is already predicted by the periodicals to exceed the supply of trained engineers.

The demand for designers capable of fast, efficient and successful design with ASICs is exceeding the supply and the predictions for the future show a projected shortage. In addition to adding engineers to meet the demand, the productivity of each designer will need to be drastically increased.

Designers must choose from a complex array of new products, new technologies, changing standards, a wide range of support, changes in packaging, varied design tools, and changing design rules, while evaluating cost-effectiveness of the final product. Workstations are evolving, changing platforms, expanding features, and moving from device to board to system level capabilites.

Note: While this book was being written, Daisy went from one of the leading vendors to nothing, Valid transferred to the SUN platform, obsoleting the SCALD system, hardware emulators were beginning to be interesting, virtual memory was recognized as probably useful for the big designs, the average array speed went from 280MHz to over 1.2Ghz, the ASIC array size went from 1000 gates to over 100,000 gates (30,000 useable), and design rules for the newer arrays were rated as four times more complicated then before. In the time since, we have reached successful 750,000 gate designs and higher, have reduced technology from 0.35 to 0.18 micron and switched from schematic capture to Verilog or VHDL input. Design tools have advanced to pick up the intermediate steps between the larger packages and tools to remove manual operations and make on-screen design a reality. Array vendors start as many FPGAs and ASICs and are outsourcing their libraries. EDA houses are supplying libraries alsog with a full design flow tools set, usually with the intention of being the sole vendor for all of the array designer's needs.

With the size, simulations became longer and 4K vectors were no longer a reasonable limit for test vectors, packaging was pushed to its limits and beyond, simulators were faced with the need for hardware-assist, timing verifiers became non-unique in the design cycle, frameworks began to be spoken of if not heavily used, behavioral languages (HDL, VHDL) were accepted in marketing vocabulary and then supported - and are now the accepted design start. These changes are only some of the ongoing evolution made over the past five years.

Pick up any magazine or newspaper devoted to ASIC and at least one article will decry the monumental task facing the design engineer in the 90's and forward. There is a constant need to acquire new skills, understand and master new tools and accept new array design restrictions and features. And not only is the designer faced with the choice of which vendor and what product, but also with the management of the design once started. The design tools that do exist may not work together making design management a complex and error-prone process.

As with any new technology, the engineer can choose to study the product and its support from the design manuals, datasheets and reading literature. ASIC array vendors provide design manuals to assist the designer in completing a successful design submission, that point of transfer between the design and the vendor.

Vendors maintain applications support engineers to answer questions and to guide the customer-designer through the submission process. This "earn while you learn" is acceptable in some cases, where design schedules will allow the weeks or months it takes for the engineer to "get up to speed" and to redo those design phases that failed due to misunderstanding of the technology and its limits.


Copyright @ 2001, 2002 Donnamaie E. White, White Enterprises
For problems or questions on these pages, contact dew@Donnamaie.com