Low-Power Low-Leakage FPGA Design Using Zigzag Power Gating, Dual-VTH/VDD and Micro-VDD-Hopping

Canh Quang TRAN  Hiroshi KAWAGUCHI  Takayasu SAKURAI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E89-C   No.3   pp.280-286
Publication Date: 2006/03/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.3.280
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on VLSI Design Technology in the Sub-100 nm Era)
Category: Low Power Techniques
Keyword: 
FPGA,  low power,  low leakage,  VDD hopping,  Zigzag power-gating,  

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Summary: 
A low-power FPGA design approach is proposed based on a fine-grain VDD control scheme called micro-VDD-hopping. Four configurable logic blocks (CLBs) are grouped into one block where VDD is shared. In the micro-VDD-hopping scheme, VDD in each block is changed between VDDH (high VDD) and VDDL (low VDD) spatially and temporally in order to achieve lower power without performance degraded. A low-power level shifter that has less contention is also proposed for low-swing inter-block signals. The FPGA incorporates the Zigzag power-gating scheme, in which special care has been taken to cope with a sneak leakage-path problem. A test chip was fabricated using a 0.35-µm CMOS technology, together with the conventional fixed-VDD FPGA for comparison. Measurement results show that dynamic power in the proposed scheme can be reduced by 86% when a frequency is half of the maximum one. Simulation using a 90-nm CMOS technology shows that leakage power can be reduced by 97%, when the proposed method is used. The area overhead of the proposed FPGA is 2%.