White Paper
Cyclone vs. Spartan-3 Performance Analysis
Introduction
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™
The Altera Cyclone FPGA family is the low-cost FPGA performance leader, outperforming the Xilinx
Spartan-3 family by an average of 70.2% when comparing the fastest speed-grade devices for both
families. Even the slowest speed-grade Cyclone devices have an average of 29.6% performance advantage
over the fastest speed-grade Spartan-3 devices, according to our benchmark results, clearly making the
Cyclone FPGA family the performance leader.
This white paper demonstrates the Cyclone family performance leadership by presenting complete
benchmark data and a detailed analysis.
Benchmark Methodology
The benchmark was conducted using 49 designs collected from various customers in different market
segments. Designs that include heavy use of multipliers represent a significant part of the benchmarked
designs. The total number of designs in the low-cost FPGA benchmark suite (Cyclone vs. Spartan-3) is
smaller than the number of designs in high-performance FPGA benchmark suite
™
(Stratix vs. Virtex-II Pro) because the density range for low-cost devices is narrower than the density
range for high-performance devices.
For design synthesis, two independent experiments were exercised to obtain the results from commercially
available synthesis software (i.e., Synplify from Synplicity) and the synthesis tools integrated in Altera and
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Xilinx software. The place-and-route and timing analysis for each design are completed in Altera Quartus
II software and Xilinx ISE software.
Both the fastest and slowest speed-grade Cyclone devices were used to compare with the fastest speedgrade Spartan-3 devices.
Table 1 provides the basic information about the software and devices used in the benchmark. Refer to the
FPGA Performance Benchmark Methodology white paper [3] for detailed benchmark methodology
discussions.
Table 1. Benchmark Setup
Vendor
Altera
Xilinx
FPGA
Family
Speed-Grade
Cyclone
Family
Spartan-3
Family
Fastest (-6) and
Slowest (-8)
Fastest (-5)
April 2004, ver. 1.0
WP-CYCSPTN3PA-1.0
Synthesis Tool
3rd party
Integrated Tool
Synplify 7.5.0
Quartus Integrated
Synthesis (QIS)
Xilinx Synthesis
Technology (XST)
Synplify 7.5.0
Place-and Route Tool
Quartus II version 4.0
Service Pack 1
ISE 6.2i Service Pack 1
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Cyclone vs. Spartan-3 Performance Analysis
Altera Corporation
Benchmarking Results
The benchmark data include the results from using the commercial synthesis tool, Synplify, and the
synthesis tools integrated in Quartus II and ISE software. For performance ratios in figures shown in this
section, the followings apply:
●
●
●
performance ratio > 1 : Cyclone device outperforms Spartan-3 device
performance ratio = 1 : Cyclone and Spartan-3 devices show the same performance
performance ratio < 1 : Spartan-3 device outperforms Cyclone device
Benchmark Results Using Synpilfy
Based on the benchmark data, comparing the fastest speed-grade devices for both Cyclone and Spartan-3
families, 130-nm Cyclone devices show a stunning 70.2% performance advantage over 90-nm Spartan-3
devices. The Cyclone family outperforms Spartan-3 in 48 of the 49 design – an outstanding 98% winning
rate. Figure 1 shows the benchmark data comparing the performance of the fastest devices for both
Cyclone and Spartan-3 families.
Figure 1. Fastest Speed-Grade Cyclone Devices vs. Fastest Speed-Grade Spartan-3 Devices
Performance Comparison
Note:
(1) Data are collected using best effort software settings. Refer to FPGA Performance Benchmarking Methodology white paper.
The Cyclone performance advantage is so pronounced that even the slowest speed-grade Cyclone device
outperforms the fastest speed-grade devices by an average of 29.6%. The slowest speed-grade Cyclone
product outperforms the fastest speed-grade Spartan-3 family in 43 of the 49 designs. Figure 2 shows the
results for slowest speed-grade Cyclone devices vs. fastest speed-grade Spartan-3 devices.
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Cyclone vs. Spartan-3 Performance Analysis
Figure 2. Slowest Speed-Grade Cyclone Devices vs. Fastest Speed-Grade Spartan-3 Devices
Performance Comparison
Note:
(1) Data are collected using best effort software settings. Refer to FPGA Performance Benchmarking Methodology white paper.
Benchmark Results Using QIS and XST
To simulate the user experience for using low-cost FPGAs and lowest-cost FPGA tools, Altera compared
Cyclone and Spartan-3 performance using synthesis tools integrated with the FPGA vendors’ software.
This experiment uses Quartus Integrated Synthesis (QIS) in the Quartus II software for Cyclone devices
and Xilinx Synthesis Technology (XST) in ISE software for Spartan-3 devices. This experiment uses the
fastest speed-grade Cyclone and Spartan-3 devices and there are 33 designs; the design count reduction is
mainly attributed to issues with the XST tool where the designs cannot pass through the XST.
The benchmark results show that Cyclone devices outperform Spartan-3 by an average of 103.1%. The
Cyclone family wins all 33 designs. Figure 3 shows the results for this benchmark.
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Cyclone vs. Spartan-3 Performance Analysis
Altera Corporation
Figure 3. Cyclone-QIS vs. Spartan-3-XST Performance Comparison
Notes:
(1) Data are collected using least effort software settings. Refer to FPGA Performance Benchmarking Methodology white paper.
(2) The lower number of designs in the QIS and XST flow is mainly attributed to the designs that cannot pass through XST.
Cyclone FPGA Advantages
The combination of the industry leading Quartus II place-and-route engine and the outstanding
performance of the Cyclone architecture enable the Cyclone FPGA family to be the performance leader in
the low-cost FPGA space.
Advanced EDA Tool - The Quartus II Software
The Quartus II software technology leadership produces optimal performance results for the Cyclone
device family.
Xilinx collateral [6] refers to the UCLA study, “Optimality and Stability Study of Timing-Driven
Placement Algorithms,” [1] which finds that the Xilinx ISE placer was 4.1% from optimal. The same
research shows that Quartus II software is only 3.0% away from the optimal, setting the Quartus II
software as the most optimal FPGA place-and-route software in the industry. Xilinx collateral omits this
point and incorrectly suggests that Xilinx tools outperform other tools in the industry [6].
In addition to the leadership in the place-and-route engine, the Quartus II software timing analyzer
performs thorough timing analysis and handles many timing analysis pitfalls [4] to reduce the risk of
design failure due to improper analysis. The Design Space Explorer (DSE) and integrated physical
synthesis technology further strengthen the Quartus II leadership in the timing closure technology,
allowing designers an automated mechanism for obtaining the best performance for their systems in an
FPGA.
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Altera Corporation
Cyclone vs. Spartan-3 Performance Analysis
Look-up Table and Routing Resource Performance
The performance of an FPGA is determined by a combination of the silicon fabrication process, logic and
routing structure, dedicated features, I/O support, and the maturity of the EDA tool. By examining the
equivalent micro timing parameters such as the look-up table (LUT), routing segments, and dedicated
features, they serve as indicators of how one FPGA architecture compares against another.
The Cyclone LUT distinct attribute allows different propagation delay depending on which input is taken
(See Figure 4). The Quartus II software automatically takes full advantage of this ability and rotates inputs
to the LUT such that the critical path of a design enjoys the fast path through the LUT. However, the
delay of the Spartan-3 LUT is modeled to be the same for each of its input in the Xilinx ISE 6.2i software.
When the fastest LUT path is taken, Cyclone LUT provides over 6x performance gain over a Spartan-3
LUT. Even when the LUT path with the most delay is used, Cyclone LUT still provides a 43%
performance improvement over the Spartan-3 LUT.
Figure 4. Cyclone LUT vs. Spartan-3 LUT and Dedicated Multiplexer Delay Comparison
Similar to the Virtex-II Pro family, the Spartan-3 family includes dedicated multiplexers (MUXF) as
function expanders. These dedicated multiplexers in both the Virtex-II Pro and Spartan-3 families are often
assumed capable of increasing large logic function performance [7]. Figure 5 shows the delay of the
Spartan-3 LUT and MUXF. The delay of the Spartan-3 MUXF is about the same as a LUT, consequently,
MUXFs provide no real improvement in logic performance. Furthermore, with the excessive delay from
the MUXFs, each MUXF should be considered a distinct logic level, contrary to the Xilinx white paper
WP206 [6] which only considers LUTs as logic levels.
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Cyclone vs. Spartan-3 Performance Analysis
Altera Corporation
Figure 5. Cyclone vs. Spartan-3 Logic Delay Comparison
Routing delay is also a reference point for determining the overall FPGA performance. The Cyclone family
consistently provides better performance than Spartan-3 as shown in Figure 6. On average, for each
increment in LUT distance, the Cyclone path delay increases by 5.8ps versus 9.5ps in Spartan-3. Cyclone
routing resources offer an average of 39% faster performance per incremental LUT distance.
Figure 6. Path Delay vs. Distance Profile for Cyclone and Spartan-3 Devices
Notes:
(1) Cyclone EP1C20 -6 speed-grade and Spartan-3 XC3S5000 -5 speed-grade are used.
(2) Cyclone and Spartan-3 data are extracted from Quartus II version 4.0 service pack 1 and ISE 6.2i service pack 1, respectively.
(3) Delay is measured for the path between two registers without logic components (such as LUT, dedicated multiplexers, etc.).
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Altera Corporation
Cyclone vs. Spartan-3 Performance Analysis
To further analyze the performance differences between the Cyclone and Spartan-3 families, a set of 46
design building blocks in 18 categories has been benchmarked. These building blocks, ranging from
counters to wide logic functions to multiplexers and parity checkers, are commonly found in any design.
The Cyclone family outperforms Spartan-3 in all 18 design categories and is on average 61% faster. Figure
7 shows the Cyclone and Spartan-3 performance comparison in each category.
Figure 7. Design Building Block Performance Comparison between Cyclone and Spartan-3
Notes:
(1) Cyclone -6 speed-grade and Spartan-3 -5 speed-grade devices are used.
(2) Designs are synthesized by Quartus Integrated Synthesis and Xilinx Synthesis Technology (XST) for Cyclone and Spartan-3,
respectively.
(3) Quartus II version 4.0 service pack 1 and ISE 6.2i service pack 1 are used for place-and-route and timing analysis for Cyclone and
Spartan-3, respectively.
Conclusion
Low-cost FPGA performance is critical in allowing designers to comfortably meet system performance
goals and accelerate time-to-market for their systems. The Cyclone FPGA family outperforms the
Spartan-3 family by an average of 70.2% based on the benchmark results using real customer designs.
Even the slowest speed-grade Cyclone devices are 29.6% faster than the fastest speed-grade Spartan-3
devices, clearly making the Cyclone device family the low-cost FPGA performance leader.
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Cyclone vs. Spartan-3 Performance Analysis
Altera Corporation
References
[1]
Cong J., Romesis M., and Xie M. Optimality and Stability Study of Timing-Driven Placement
Algorithms, UCLA Technical Report 030030. (http://cadlab.cs.ucla.edu/~michail/tpeko.pdf)
[2]
Altera Cyclone Handbook
[3]
Altera white paper, “FPGA Performance Benchmarking Methodology”
[4]
Altera white paper, “Performing Equivalent Timing Analysis Between the Altera Quartus II
Software and Xilinx ISE”
[5]
Xilinx Data Sheet, DS099, “Spartan-3 FPGAs Complete Data Sheet,” March 4, 2004
[6]
Xilinx white paper, WP206, “The 40% Performance Advantage of Virtex-II Pro FPGAs over
Competitive PLDs,” version 1.2, March 1, 2004
[7]
Xilinx white paper, WP209, “Virtex Variable-Input LUT Architecture,” version 1.0, January 12,
2004
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Cyclone vs. Spartan-3 Performance Analysis
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