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DSPs face new competition

Posted: 16 Jun 2003 ?? ?Print Version ?Bookmark and Share

Keywords:dsp? digital signal processing? fpga? asic? general-purpose processor?

In the last few years, signal processing has become important in an ever-expanding range of applications, from digital still cameras to engine controllers. This rapid growth of signal processing has been a boon for DSP vendors. Cellphones, for example, will consume hundreds of millions of DSP cores this year. But as signal processing expands into new applications, DSPs are increasingly placed in direct competition with other types of chips--and DSPs sometimes lose in these showdowns.

In the hot growth area of consumer electronics, for example, DSPs face increasing competition from embedded general purpose processors. Even without signal-processing-specific features, many general purpose processors can handle low to moderate signal-processing tasks. Moreover, designers of general purpose processors are adding signal-processing features to their architectures, enabling the processors to handle tougher signal-processing applications. The ARM processor core family, one of the most popular general purpose architectures for consumer electronics, illustrates this trend. The recently announced ARM11 core includes a sum-of-absolute-differences instruction, a specialized instruction that is useful mainly for video compression algorithms.

As embedded general purpose processors gain more signal-processing capabilities, factors other than performance increasingly determine whether a DSP or a general purpose processor is used for a signal-processing application. For instance, the extent and quality of the development tools and off-the-shelf software components are often critical factors in selecting a processor. Today, embedded general purpose processors often offer superior development tools and off-the-shelf software components for developers of non-signal-processing tasks like user interfaces. DSPs, in contrast, typically provide superior development support for signal-processing tasks like audio processing. If non-signal-processing software--particularly the choice of operating system--is the system designer's top concern, general purpose processors usually come out ahead.

DSPs also face increasing competition from FPGAs. Since the signal processing workloads of advanced communications infrastructure applications are outpacing the capabilities of DSPs, there are opportunities for new types of devices in these applications. FPGA vendors have responded to these opportunities by adding signal-processing features to their chips.

Until recently, FPGAs were thought to be too expensive to compete with DSPs. BDTI recently tested this assumption using a new communications receiver benchmark. The results of this study were stunning--a typical member of Altera's Stratix FPGA family could handle dozens of receiver channels on the benchmark, while high-end DSPs could not support even one channel. And even though FPGAs can be more expensive, they can also beat DSPs in terms of cost-per-channel in some applications.

But FPGAs also face significant challenges. Most engineers with expertise in signal-processing applications understand software development methods, but do not understand the hardware development methods used in FPGAs. And the signal-processing-oriented tools and IP blocks available for FPGAs are not nearly as good as the tools and software available for established DSPs. These complications create a huge disadvantage: BDTI's analysis suggests that optimizing a complex signal-processing function for an FPGA can take over five times as long as for a DSP. Despite this disadvantage, the huge performance advantages of FPGAs are making them the technology of choice for some high-end signal-processing applications.

With competitors squeezing them from the top and bottom, DSPs may seem to have a bleak future. But DSP vendors are continuing to innovate, and to make their devices attractive in a wider range of applications. For example, Analog Devices recently announced plans to support Linux on its Blackfin DSPs--a step that will make these more competitive with general purpose processors. Motorola also announced that it will combine its DSPs with reconfigurable hardware, countering the advancements in FPGAs. As signal processing continues to spread, DSPs are likely to continue borrowing features from competing technologies. Five years from now, it may be hard to take DSPs, general purpose processors and FPGAs apart.

- Jeff Bier

General Manager

Kenton Williston

Technology Analyst

Berkeley Design Technology Inc.

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