In case you haven't noticed, an interesting trend is in the offing, and it all centers on one thing—programmable logic devices (PLDs) such as field-programmable gate arrays (FPGAs). In recent years, they've carved out a niche in the prototyping arena. They let designers get prototypes up and running in a few weeks, while an ASIC takes a few months. This process has become so popular, in fact, prototyping with an FPGA and moving to an ASIC for volume production has become a common procedure.
The ability to quickly deploy FPGAs isn't the only advantage traditional ASIC designers are eying. Consider for a moment that the programmable market is one of the fastest growing segments of the semiconductor industry today. Device density is unmistakably a large contributor to this growth.
"Xilinx has recently announced a new member of the Virtex family supporting up to two million gates," says Herman Beke, CEO of Frontier Design. "This is just the start of an unstoppable trend toward higher device density. We can expect the number of gates available on an FPGA to double every year for the next few years."
These high densities, coupled with new, inexpensive, high-quantity programmable devices, mean that FPGAs no longer are seen as just an alternative to the ASIC prototype. On the contrary, with benefits like faster time-to-market and the ability to handle changing design requirements, FPGAs are now themselves being used for volume production. For many designers, the line between ASICs and FPGAs has blurred (see "Look For The Signs," p. 74).
EDA vendors have stood up and taken notice of this upsurge in the use of FPGAs and similar devices. These companies are coming to the market with a host of new tools and enhanced design features to make it easier for the traditional ASIC designer to migrate to FPGAs. Additionally, tool vendors and device suppliers are forming alliances to promote designs based on programmable logic. This translates into more options for the designer. The only questions involve how designers will choose between FPGAs and ASICs, which tradeoffs will be associated with that decision, and what obstacles lay ahead for the programmable design space.
What's the big deal about programmable logic, you ask? After all, it's been around for a long time. Why should ASIC designers, or any other types of designers for that matter, want to use it now (see "The FPGA Migration Is On," p. 78)? It's a fair question that's relatively easy to answer.
Flexibility Increasing
Engineers are opting to use FPGAs rather than ASICs because they're flexible, quick to deploy, and much more affordable than they were in the past. Did you realize that in today's consumer-driven marketplace, the lifetime of a product is often shorter than its development cycle? Time-to-market pressures are even more stringent now than in the last few years. Dealing with this pressure means designers need greater design flexibility.
The flexibility in FPGAs stems from their inherent reprogrammable nature. As Phil Lewer, product marketing manager of Viewlogic, explains, "This allows additional functionality to be added to an end product that is actually deployed in the field without having to physically modify the board. In contrast, if you want to change the functionality of an ASIC, you would need to make a new ASIC, resulting in physical changes having to be made to the board."
Along with this flexibility comes a lower risk factor that many designers find desirable. With FPGAs, mistakes can be corrected and design revisions can be made simply by reprogramming them. By comparison, if the design is realized in an ASIC, any mistake will require a new set of masks and a new production run. This is a cost and time drain.
Such benefits have become increasingly advantageous for engineers designing consumer-based end products containing one or more standards. Take high-definition television (HDTV) consumer products. The standards governing the mechanism by which they deliver high-definition picture quality are in flux. In this case, the use of programmable technology would effectively enable the product configuration to be reprogrammed in the field, should the standard change after the set has been built and shipped to a customer.
It's not all that surprising, then, why ASIC designers might opt to use an FPGA instead of an ASIC for everything from prototyping to low-volume system production uses like beta testing and volume production. Nor is it any surprise that programmable logic tends to naturally lend itself to use in certain applications areas. It is, for instance, ideally suited for those applications where time-to-market is far more important than absolute performance or product cost, or where system performance is dictated by an interface speed. This is the case with networking and telecommunications applications.
Some designers might be surprised that this programmable-logic trend isn't limited to the traditional ASIC design community. Bill Wignall, president and chief operating officer of Electronics Workbench, points out that "PLDs/CPLDs (complex programmable-logic devices) are now sufficiently complex to handle pc boards. As a result, we now see designers putting what used to be on a board onto PLDs/CPLDs."