Changes in Analog Design

Electronic News, Oct 23, 2000 by Michael Brunolli

RECRUTING PROFESSIONALS tell us that a good analog design engineer is a rare find. Has the changing role of the mixed signal designer contributed to this apparent shortage?

The role of the analog engineer in system design has undergone a significant change in the last decade. The emphasis on digital processing advances affected the supply and demand for analog engineers until the recent system-on-a-chip (SOC) revolution. The SOC advance has transformed the mixed signal engineer from a designer of commodity components to an essential member of the system-integration team. As a result, the demand for and challenges facing analog professionals never have been higher.

During the 1960s, '70s and '80s, the role of analog design engineers was to provide standalone building blocks that could be used by system implementers to satisfy customer needs. They focused on increasing performance and lowering cost through the use of custom analog IC processes, specialized packaging techniques and often controlled environments.

Over the course of those decades, IC fabrication processes continued to rapidly improve in speed and density, as described by Moore's Law. The industry also witnessed steady and significant progress in DSP architecture, analysis methods and EDA tools. These two factors brought about a stunning increase in digital processing capabilities. Educational institutions supported this progress by focusing engineering coursework on digital design while slowly reducing the emphasis on analog training. Thus, the supply of new analog engineers has declined at the same time that veteran designers are moving up the corporate ladder.

Next came the SOC era, changing the role of the analog designer forever. Analog engineers, recast as mixed signal designers, find themselves on the hot seat with a host of new challenges. Their designs have to achieve performance similar to that of stand-alone devices, while using standard digital IC fabrication in a high-noise environment with reduced power supply voltages. Mixed signal engineers now realize that they must be involved at the chip level in every aspect of the design.

The most severe problem they face, however, is the acceleration in power-supply voltage scaling. The relentless scaling of features has broken down the reluctance to shrink supply voltages so that even within a single generation, there may be three different voltage options. These low voltages result in higher sensitivity to noise, smaller operating ranges and limitations on architectural choices. Many of the best-performing circuits are not applicable at low-supply voltages. Thus, the analog designer must come up with new inventions for every process generation. This constant change has limited the development of useful productivity tools for mixed signal designers. It has also hampered the growth of the analog intellectual property industry, further limiting the design leverage that could be realized in a less dynamic situation.

Where once the system architects could specify analog functions from a broad spectrum of suppliers, they must now work with a set of limited implementations suitable for SOC integration. As a result, system designers have now identified the performance of the analog function as the limiting factor in an SOC, restricting the achievable design margins and function. This awareness of the importance of analog expertise to SOC design has sent companies scrambling for talented engineers in the field, only to find the shortage in supply created by the previous success of the digital world. To remain competitive, companies must get the most from the analog expertise already in house with better training and analog design tools, and make the recruitment of qualified individuals a top priority.

Michael Brunolli is chief technical officer at NurLogic in San Diego.