Stratix IV FPGAs: The World's Biggest 40-nm FPGA
At the 40-nm process node, Stratix® IV FPGAs provide unmatched resources for integrating your next-generation, high-performance designs. Figure 1 compares the largest device in the Stratix IV FPGA family to that of the nearest competitor.
Figure 1. Stratix IV Resources Compared to Nearest Competing FPGA
The Stratix IV FPGA family two device variants:
- Stratix IV E (enhanced) FPGAs: Up to 680K LEs, 22.4-Mbit RAM, 1,360 18 x 18-bit multipliers
- Stratix IV GX (enhanced with transceivers) FPGAs: Up to 530K logic elements (LEs) and 48 full-duplex CDR-based transceivers at up to 8.5 Gbps
Logic Efficiency
The core fabric of Stratix IV FPGAs is built from innovative logic units known as adaptive logic modules (ALMs). ALMs are extremely efficient in implementing logic because of their fracturability. Figure 2 shows the results of benchmarks done on a set of 65 customer designs. The horizontal black line at the 1 mark indicates a point at which the number of logic elements for Virtex-5 (LUT-FF pair) and Stratix IV (ALMs) are the same. The results show that:
- On average, the ALM can pack 1.8x more logic than the Virtex-5 LUT-FF pair. For an equivalent sized part, Stratix IV FPGAs can implement more logic than the nearest competing device. Hence, a Stratix IV EP4SE680 (with 272440K ALMs) has 2.4x more logic capacity than Virtex-5 XC5VLX330 (207,360 LUT-FF pairs).
Figure 2. Stratix IV ALM vs. Virtex-5 LUT-FF Pair Logic Density Benchmark
ALM fracturability allows two independent smaller functions to be implemented in one ALM, instead of partially filling two LEs and wasting the unutilized resources. Altera’s Quartus® II software automatically takes advantage of this and packs the design efficiently, minimizing under-utilized resources. This opens the door for fitting the design into smaller devices and reducing logic levels to increase fMAX.
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