``The SFRA: A Corner-Turn FPGA Architecture''
Proceedings of the 2004 ACM/SIGDA 12th International Symposium on
Field-Programmable Gate Arrays
(FPGA '04, February 22-24, 2004),
FPGAs normally operate at whatever clock rate is appropriate for the loaded
When FPGAs are used as computational devices in a larger system, however, it
is better to employ fixed-frequency FPGAs operating at a high clock
Such fixed-frequency arrays require pipelined interconnect structures, which
are difficult to support in a traditional FPGA architecture.
We have developed a novel approach, called a ``corner-turn'' interconnect,
based on a Manhattan array of logically depopulated S-boxes
with full connectivity but limited routability.
This interconnect supports new polynomial-time routing techniques while
maintaining conventional placement and other upstream toolflow.
We have used the corner-turn interconnect to define a fixed-frequency FPGA
architecture, the SFRA, that is largely compatible with the Xilinx Virtex
while providing higher speed, pipelined operation.
Our tools automatically repipeline designs to operate at the SFRA's
intrinsic clock frequency.
Since the arrays are largely compatible, we directly compare the SFRA with
the Virtex on four benchmark designs.
On these benchmarks, the SFRA offers higher throughput and competitive
throughput per area.
The SFRA routing and retiming tools also run one to two orders of magnitude
faster than their Xilinx counterparts.
2004 August 5