Reliability- and Variation-Aware Placement for Field-Programmable Gate Arrays

Abstract

Field-programmable gate arrays (FPGAs) have the potential to address scaling challenges in CMOS technology because of their regular structures and the flexibility they possess by being re-configurable after fabrication. One of the potential approaches in attacking scaling challenges, such as negative-bias temperature instability (NBTI) and process variation (PV), is by using placement techniques that are aware of these problems. Such techniques aim at placing a circuit in an FPGA such that the critical path delay is improved compared to the expected worst case. This can be achieved by placing NBTI-critical blocks of a circuit in areas with fast transistors in an FPGA chip.

In this thesis, we present a detailed research effort that addresses the joint effect of NBTI and PV in FPGAs. We follow an experimental methodology in that we use actual PV data that we measure from 15 FPGA chips. The measured data is used to study the joint effect of NBTI and PV on the timing performance of circuits that are placed and routed in FPGAs. Enhancements are made to a well-known FPGA placement algorithm, T-VPlace, in order to make the placement process aware of the joint effect of NBTI and PV. Results are given for the placement and routing of Microelectronics Center of North Carolina (MCNC) benchmark circuits to show the effectiveness of the proposed techniques in addressing scaling challenges in FPGAs.