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Spartan-3A DSP

Greg Brown, Sr. Manager, IC Marketing, Processing Solutions Group, Xilinx, Inc.

The latest addition to the XtremeDSP Platform portfolio takes price/performance to a new level.

The search for the best DSP solution for a given application usually leads a designer
into a maze of price, performance and power consumption tradeoffs, often requiring a
compromise of one to accommodate the other two. With the introduction of Spartan-3A DSP,
the latest addition to the XtremeDSP Platform portfolio and the first Spartan FPGA to be
optimized, Xilinx has broken through the maze to deliver the most efficient combination of
these three critical values for a host of applications, including wireless basestations,
mobile defense communications systems, surveillance
networks, automotive, and medical imaging technologies.

Spartan-3A DSP delivers up to 32 GMAC/s or more (32 billion Multiply-Accumulate
operations per second) and 2200 Mbps memory bandwidth at a volume price of sub -$40. This
represents an unprecedented price/performance breakthrough that hits the mark for price
and power-sensitive applications
like the digital front-end (DFE) and baseband solutions in a single-channel picocell
wireless basestation, military mobile software-defined radios (SDRs), ultrasound systems,
driver assistance/media systems and Smart IP cameras.

Moreover, with up to 53,712 logic cells, 2268 kbits of Block RAM, 373 kbits of
distributed RAM,, and newly developed hibernate/suspend power management features,
Spartan-3 DSP offers enough integration capacity and memory bandwidth to drive
price-performance-power ratios even lower. Add to this the inherent benefits afforded by
FPGA-based DSP solutions—lower risk through design flexibility and faster time to
market—and the value of the Spartan-3 DSP platform becomes increasingly apparent (see
Table 1).

DSP-Optimized Spartan FPGAs

At the heart of the Spartan-3A DSP is a modified version of the DSP48 slice—the
DSP48A. Initially introduced with the release of Virtex-4 FPGAs, the DSP48 slice is an
Application Specific Modular Block (ASMBL™) that powers the DSP functions in Virtex-4
and Virtex-5 devices. These help designers implement solutions to complex challenges,
i.e., hundreds of IF-to-baseband down-conversion channels, 128X chip-rate processing for
3G spreadspectrum systems, high-definition H.264 and MPEG-4 encode/decode algorithms.

A DSP48 Slice (also called an XtremeDSP Slice ) contains two DSP48 slices to form the
basis of a versatile, coarse-grained DSP architecture. The DSP48 slices support many
independent functions, including multiplier, multiplier-accumulator (MACC), multiplier
followed by an adder, three-input adder, barrel shifter, wide bus multiplexers, magnitude
comparator, or wide counter. The architecture also supports connecting multiple DSP48
slices to form wide math functions, DSP filters, and complex arithmetic
functions without the use of general FPGA fabric, thereby reducing power consumption while
delivering very high performance
and efficient silicon utilization.

Spartan-3A DSP is the first member of the Spartan generation FPGA to incorporate a
DSP48 slice, or more specifically, the DSP48A slice. This new DSP block (see Figure 1) is
similar to the DSP48 slice, with two essential
differences: the use of a two-input 48-bit adder at the output of the 18X18 multiplier
(rather than the three-input adder used in the DSP48) and the addition of a pre-adder at
the input of the slice. This enables further slice optimization, for functions such as FIR
filters.

Application Impact

The price/performance/power efficiency made possible by Spartan-3A DSP devices, a
single Spartan-3A DSP 1800A can dramatically
reduce system cost in a Smart IP camera application, absorbing the entire video pipeline
section in the process. For high-volume consumer applications such as the Smart IP camera,
this represents tremendous value to the manufacturer that goes directly to the bottom
line. Add to this the savings in power, footprint and bill of materials (BOM) and the
impact that Spartan-3A DSP can have on profitability, reliability and product migration is
unparalleled.

In some cases such as the SDR for mobile defense communications, the Spartan-3A DSP can
serve as a reconfigurable co-processor
to a discrete DSP, providing both the aforementioned price/performance/power economies as
well as eliminating the need for duplicate circuitry to support multiple waveforms.

Clearly, in every application for which Spartan-3A DSP is an appropriate solution, the
result is greater efficiency in performance,
power and price. Although by no means exhaustive.

XtremeDSP Solutions

The fundamental goal of this on-going initiative is to create and continuously evolve a
range of application-optimized DSP solutions that keep pace with the high-performance DSP
demands of the communications,
MVI and defense industries. The top-level deliverables for XtremeDSP Solutions
include:

A continuously expanding portfolio of high-performance devices for DSP designs
Development boards, reference designs and Intellectual Property (IP)
Design and development tools for varied approaches to DSP system design
Complementary programmable logic and embedded processing functions
Strategic industry and university partnerships
for training and support

Summary

In the DSP marketplace, it’s not always the fastest, the most inexpensive or the most
power-efficient processor that wins, but the one that provides the best fit in
application. For a large and growing number of applications,
Spartan-3A DSP provides the most efficient combination of price, performance and power
consumption, backed by a robust set of tools, IP and support infrastructure. If your next
DSP design needs extreme efficiency,
you may need the latest XtremeDSP Solution from Xilinx.