Discontinuities In System-Level Design

Electronic News, July 2, 2001 by Walden C. Rhines

The following is third in a series off our executive viewpoints authorea by Walden C. Rhines, chairman and CEO of Mentor Graphics Corp., on behalf of Electronic News, on the most critical challenges that are currently facing designers and EDA vendors alike.

One of the most unexpected shifts in design methodologies is happening in PCB design. Several business and technology trends have converged, impacting the PCB portion of the design process and driving the need for new tools. Today the industry is witnessing a veritable rebirth in PCB design.

The PCB design segment of the EDA industry has been marked by slow to zero growth for many years. According to San Jose-based Gartner Dataquest research, the PCB design software market grew 0 percent to 5 percent annually during the early 1990s. Recently, this situation has changed dramatically. In the last four quarters alone the PCB design market has grown more quickly than the EDA industry overall.

What's driving this seemingly sudden shift in focus back to the PCB? Impacted by several converging factors, the PCB designer is now faced with the types of challenges that have long been familiar to the IC designer: increasing complexity and performance requirements along with ever greater time-to-market pressures. As a result, the PCB is now back on the critical path.

In the late 1980s and early 1990s, a typical PCB included multiple large ASICs; the cycle time-to-market was driven by the typical design time of the ASICs, which averaged 12 months. By comparison, the typical time required for board design -- about seven days to lay out the board, send it out and make changes -- was inconsequential to the overall design time.

Since then, PCB design has been impacted in several ways by multiple changes within the electronics industry. Trends such as the increased use of standard components, the growing use of field-programmable logic instead of ASICs and the high demand for mixed signal designs from the fast-growing telecommunications segment have all impacted the requirements for the PCB.

For example, the move from ICs to field-programmable logic devices has shortened the design cycle considerably. While previously the IC design was the deciding factor in finalizing a design, manufacturers found that with increased use of field-programmable logic devices, the board began holding things up. These programmable logic devices are not only faster and cheaper to design, but they also complicate the board layout with difficult staggered pin connectors and new speed requirements.

At the same time, the complexity of the boards has also continued to increase, impacted by some of these same trends. For example, in addition to shortening the overall design time, the move to FPGAs with staggered pin connectors has also impacted board design. Today, leading system designers in cutting edge industries such as telecommunications are designing 20-layer boards with 20-mil traces and blind and buried vias.

The typical PCB now is likely to include several standard components and off-the-shelf chips, along with programmable logic and support for multiple communications standards. In addition, the use of new packaging technologies such as BGA has added to the challenges for board designers. The use of SOC designs has further increased the overall circuit density requiring advanced board design techniques. High-speed design, with high-speed nets over the 50MHz threshold, now accounts for more than 60 percent of all PCB design, posing additional challenges to the PCB designer.

In addition to these technology issues, the human factors involved have brought other changes to the way PCB design is done. Today's global companies have design teams working together from various worldwide locations. It has also become fairly common to outsource various portions of the process, from design to manufacture. All of these changes necessitate a system design solution that requires that more people have access to component design data, mechanical system information, manufacturing constraints and other details. This in turn necessitates a leap in design data management.

Companies that are able to foresee these discontinuities and anticipate the impact of changes in the industry will be able to adopt new tools and methodologies in advance, allowing them to turn out better, faster and cheaper products than their competitors. By encouraging designers and EDA companies to communicate, we can avoid a gap between today's methodology and the next shift in technology.

The final installment in Rhines' Executive Viewpoints will focus on changes in the area of physical verification with the advent of sub wavelength manufacturability and one expected technology breakdown that simply didn't happen.