DSP silicon takes many forms

The market for chips based on digital signal processing (DSP) technology is far greater than the "DSP chip" market. Forward Concepts estimates that the traditional DSP chip market is only a third of the total market for DSP-based silicon. Certainly, the general-purpose programmable DSP is the most visible product, since the newest versions represent state-of-the-art semiconductor technology in addition to novel architectures that make them the product of choice for most new DSP applications. And it is the great breadth and depth of development tools and software support that makes those traditional DSPs the first place to prove in new product concepts.

[For an in-depth review of traditional DSPs, see A Survey of Mainstream DSP Processors.]

However, there are a number of other chips based on DSP technology that people don't call DSP chips. For example, simple MP3 players are based on DSP technology, but most are based on RISC chips with added DSP hardware. That's feasible because the DSP "horsepower" demands for decoding MP3 music are relatively modest. And, because of the high volumes involved, MP3 player chips tend to be ASICs based on system-on-chip (SoC) solutions. All of the traditional RISC IP vendors like ARC, ARM, MIPS and Tensilica have added DSP capabilities to their product offerings.

But when more DSP horsepower is required, ASICs are often implemented using DSP cores, whether fabricated by one of the traditional DSP chip houses using their own cores or through licensed cores from companies offering DSP IP, like Ceva and VeriSilicon.

Field-Programmable Gate Arrays (FPGAs) are also popular for an increasing number of applications, not only because of their significant speed, but also because of their flexibility. FPGAs have been implemented as the fastest instances of DSP silicon. Truth be known, Altera and Xilinx are major vendors of DSP silicon, with DSP revenues that rival those of some traditional DSP chip suppliers.

"Hardwired" DSPs are often required for inexpensive high-speed computation like MPEG-4 or H.264 decoding and tend to be based largely on state machines and SIMD cores rather than conventional DSPs. MPUs (especially the PowerPC) and MCUs (like Freescale's ColdFire products) are also employed in DSP-specific products. Media processors and so-called "application processors" are special cases of DSP-capable RISC engines designed for audio/video applications.

A number of chip vendors employ their own proprietary DSP core. For example, Qualcomm, the second largest vendor of DSP silicon (not "DSP chips") employs theirs in a portfolio of cellphone baseband chips. Since the company sells no off-the-shelf programmable DSPs, their involvement in DSP technology often goes unnoticed. Other major vendors of DSP silicon that don't sell DSP chips include Marvell Semiconductor, Infineon and Broadcom.

To illustrate the variety of chips employed for DSP functions, the results from our latest survey of DSP professionals are presented in the accompanying chart. Note that programmable DSPs, in the forms of fixed-point and floating-point chips, were the most popular responses by our survey audience, but there were other computational platforms employed for DSP that were also cited. Note that multiple responses were allowed, and many respondents employ both general-purpose DSPs and one or more of the other platforms. For example, conventional DSPs coupled with FPGAs are popular for wireless base station applications.