Timing-Driven Nonuniform Depopulation-Based Clustering

Abstract

Low-cost FPGAs have comparable number of Configurable Logic Blocks (CLBs) with respect to resource-rich FPGAs but have much less routing tracks. For CAD tools, this situation increases the difficulty of successfully mapping a circuit into the lowcost FPGAs. Instead of switching to resource-rich FPGAs, the designers could employ depopulation-based clustering techniques which underuse CLBs, hence improve routability by spreading the logic over the architecture. However, all depopulation-based clustering algorithms to this date increase critical path delay. In this paper, we present a timing-driven nonuniform depopulationbased clustering technique, T-NDPack, that targets critical path delay and channel width constraints simultaneously. T-NDPack adjusts the CLB capacity based on the criticality of the Basic Logic Element (BLE). Results show that T-NDPack reduces minimum channel width by 11.07% while increasing the number of CLBs by 13.28% compared to T-VPack. More importantly, T-NDPack decreases critical path delay by 2.89%.

MogaMap and DynPack

“…A timing-driven non-uniform depopulation based clustering named T-NDPACK is introduced in [8]. The technique targets achieve better channel width by spreading strongly connected CLBs over a large area on the FPGA.…”

K-way partitioning based packing for FPGA logic blocks without input bandwidth constraint

“…Other packing approaches based on seed selection and BLE attraction are proposed in the literature: RPack [7], which improves routability by including a routability factor into cost function and its results are close to that of T-VPack; P-TVPack [18], which improves power by including switch activity factor into the cost function; MO-Pack [15], which improves multiple objectives by incorporating multiple cost factors in the cost function; T-NDPack [16] and Un/DoPack [17], which use depopulation to improve routability.…”