As we approach year-end, it seems fitting to look back at developments and trends in DSP processors. And it’s an opportune time to do so, since my colleagues and I just completed the latest iteration of our exhaustive (and exhausting) study of leading DSPs. It has been three years since we published the previous edition, and in reviewing the new version I am struck by one of the key changes in our industry.
Back in 2000, telecom was the DSP killer app. Most DSP architectural innovations were happening in 16-bit fixed-point processors, the mainstays of telecom. At that time, we wondered about the future of floating-point DSPs. They were rarely used in telecom, and were coming under competitive pressure from CPUs in their traditional markets of military, medical, and imaging equipment. The two key floating-point architectures, Analog Devices’ SHARC and Texas Instruments’ ’C67x, seemed to be stagnating.
But the telecom industry has had a rough couple of years. Although telecom is still a formidable force driving DSPs, it is starting to share the spotlight with a significant new market: consumer audio and video. This market includes DVD players, home theater equipment, digital cameras, MP3 players, and car audio. Programmable processors are an attractive choice for these applications, because they enable OEMs to differentiate their products with features like proprietary effects processing. Most portable products use fixed-point processors to minimize cost and power, but car and home audio systems often tolerate somewhat higher cost and power in exchange for better-sounding audio. This is where floating-point DSPs have found a new sweet spot.
Floating-point DSPs have been used in professional audio products for years, primarily because their 32-bit floating-point data format offers better signal fidelity than is afforded by most fixed-point processors. The floating-point format also makes it easier to implement proprietary signal processing algorithms. These advantages make floating-point DSPs a natural choice for the burgeoning consumer audio market, thus breathing fresh life into the two aging architectures. TI now offers ’C67x chips with audio-oriented I/O ports, and this month, ADI announced four new members of its SHARC family that pair aggressively increased clock speeds (up to 300 MHz) with specialized, audio-oriented on-chip peripherals.
To paraphrase Mark Twain, reports of the demise of floating-point DSPs appear to have been somewhat exaggerated. We wouldn’t be surprised if some of the most interesting DSP developments in 2004 are in the realm of floating-point DSPs.
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