1998-09-14 , E/IC-1043/64
Product News From Philips Semiconductors

Philips Semiconductors, the largest European semiconductor manufacturer, today announced the launch of its R.E.A.L. DSP (Reconfigurable Embedded DSP Architecture Low-cost/Low-power) technology, making it possible for designers to incorporate advanced digital signal processing functions into high-volume consumer products where cost and/or power consumption are critical design parameters. Fully proven in a range of telecom and audio applications, Philips Semiconductors' R.E.A.L. DSP design platform also meets the short time-to-market and IP (Intellectual Property) re-use requirements of fast-moving consumer markets.

"Real-time DSP algorithms such as those required in digital mobile phones are very computationally intensive, leading to excessive power dissipation when they are run on conventional DSP processors because of the high clock frequencies involved. For battery-powered equipment such as mobile phones, the goal is to keep the clock frequency as low as possible in order to minimise power dissipation, while at the same time keeping up functional performance," explained Rob Woudsma, head of Philips Semiconductors' Embedded Systems Technology Centre. "On top of that, however, you have to keep the silicon cost low by reducing the size of the embedded DSP core and program memory," he added.

Philips Semiconductors' R.E.A.L. DSP utilises a number of innovative techniques to achieve these objectives. Based on a dual Harvard architecture and an advanced dual multiplier/accumulator data computation unit (DCU) pioneered by Philips five years ago, R.E.A.L. DSP processes block-based algorithms such as FIR filters more than twice as fast as single multiplier/accumulator cores operating at the same clock frequency. Unlike fixed architecture DSP cores, however, R.E.A.L. DSP also adapts easily to less regular types of algorithm. Each of the processing blocks in the DCU, such as its multiplier, arithmetic logic unit and address computation units, can optionally be controlled in parallel by 96-bit user-defined Application Specific Instructions (ASIs). Stored in a look-up table and pointed to by standard 16-bit program code, these ASIs enable the programmer to select an instruction set that's specifically tailored to the application. Using these techniques, Philips Semiconductors' R.E.A.L. DSP core achieves a BDTImark™ benchmark score of 24 at 60 MIPS. **

R.E.A.L. DSP's reconfigurability isn't limited to instruction set tailoring. Users can also modify the hardware architecture of the core to suit the target application. The design platform allows parts of a DSP algorithm that would execute better on a hardware accelerator to be identified very early on in the design cycle. Application Specific Execution Units (AXUs) can then be incorporated into the data path or address calculation units of the core. VHDL descriptions of these AXUs can be merged with the VHDL description of the R.E.A.L. DSP core so that both are fully accounted for during simulation stages in the design process. Alternatively, the AXUs can be added at the placement and routing stage in the ASIC design flow.

R.E.A.L. DSP's powerful instruction and hardware customisation features, together with its highly flexible application development platform, enable interactive co-design of DSP algorithms and architectures so that an optimum hardware/software solution can be achieved before any silicon needs to be cast.

Above all, the R.E.A.L. DSP platform has been designed to meet the short time-to-market requirements of consumer product development. Fully defined and parameterised at VHDL level, existing R.E.A.L. DSP cores can be easily reconfigured to suit new applications - allowing the intellectual property and software development effort invested in one design to be transferred easily into new designs. A full suite of program development, simulation, emulation and debugging tools is already in place, including a C-compiler for generating much of the control code that surrounds DSP algorithms.

However, Philips Semiconductors is also aware that the availability of DSP oriented C compilers will be an important milestone, both in shortening the time-to-market for new designs and in making DSP technology readily accessible to a much larger number of users.

"Although 90% of the code for typical DSP applications can already take the form of compiled C programs, the time-critical inner loops of DSP algorithms that make up the remaining 10% of code yet account for 90% of the execution time, still have to be hand-optimised in assembler," said Rob Woudsma. "At best, you may be able to draw on a library of assembly language programs for standard DSP functions such as filters and FFTs, but what's ultimately needed is a C compiler that can really cope with the multiple memory spaces, complex register sets and high degree of parallelism inherent in DSP designs," he added.

To this end, Philips Semiconductors is using the CoSy compiler development platform from  ACE Associated Compiler Experts bv (Amsterdam, The Netherlands) to develop a fully DSP oriented compiler for R.E.A.L. DSP. As part of this work, it has collaborated with ACE in the development of DSP-C extensions to the ANSI-C programming language.

Philips Semiconductors' R.E.A.L. DSP technology is not primarily designed to produce stand-alone DSPs. It is intended to produce DSP cores that become integral parts of complete 'system-on-silicon' solutions. The R.E.A.L. DSP development platforms therefore integrate seamlessly into Philips Semiconductors' standardised ASIC design flow, enabling an extensive range of memory types, microcontrollers, peripherals and I/O sub-systems to be added to the final IC.

"Philips Semiconductors has more experience in consumer oriented DSP than just about anyone else," said Will Strauss, president of DSP market watcher Forward Concepts (Tempe, Arizona, USA). He went on to say, "The embodiment of this experience in its R.E.A.L. DSP technology should make a very significant impact on the consumer DSP market."

R.E.A.L. DSP is also a proven technology. Many of the reconfiguration techniques, for example, were used successfully in the development of Philips Semiconductors' previous EPICS family of DSP cores, which lie at the heart of the company's ABC DECT Baseband Controllers, its unique CAR DSP chips and its AC3/MPEG audio decoder ICs. A single multiplier/accumulator version of the R.E.A.L. DSP core is used in Philips Semiconductors' latest DTAM (Digital Telephone Answering Machine) IC, while an advanced dual multiplier/accumulator version powers the enhanced features of its latest baseband controller chip for GSM phones. This GSM baseband controller, which is an excellent example of R.E.A.L. DSP's reconfigurability, features AXUs in the form of a 40-bit barrel shifter, normalisation unit and division support unit, plus additional saturation units between the ALUs and accumulators for optimal support of GSM speech codec functions. It also makes extensive use of ASIs, both to support the AXUs and to fully exploit the parallel processing capabilities of the core.

Philips Semiconductors, a division of Koninklijke Philips Electronics NV, headquartered in Eindhoven, The Netherlands, is the ninth largest semiconductor supplier in the world and the third largest supplier of discretes in the world. Philips Semiconductors' innovations in digital audio, video, and mobile technology position the company as a leader in the consumer, multimedia and wireless communications markets. Sales offices are located in all major markets around the world and are supported by systems labs.

** Note: The R.E.A.L. DSP core has a BDTImark™ score of 24 at 60 MIPS. The BDTImark is a summary measure of DSP speed, distilled from a suite of DSP benchmarks developed by Berkeley Design Technology, Inc. (BDTI) and independently verified by BDTI for specific DSP processors. A higher BDTImark score indicates a faster processor. For a complete description of the BDTImark and underlying benchmarking methodology, as well as additional BDTImark scores, please visit  http://www.bdti.com

See also backgrounder Philips Semiconductors' R.E.A.L. DSP Core for Low-Cost Low-Power Telecommunication and Consumer Applications.