A Method for Measuring Process Variations in the FPGA Chip Considering the Effect of Wire Delay

Abstract

FPGAs are integrated circuits that can be implemented arbitrary logic functions. In FPGAs, it is important to measure process variations with high accuracy because process variations have become noticeable. A ring oscillator is widely used as a process monitor circuit. In FPGA design, a design tool automatically determines logic blocks in the chip on which a circuit is implemented and wires between the logic blocks. Designers can manually redesign/modify logic block parts, but not wire parts. Therefore, in order to measure process variations with high accuracy, it is necessary to clarify the effect of wire delay on an oscillation frequency. In this paper, ring oscillators with different wires between logic blocks are implemented on the FPGA chip and a method for measuring process variations with less effect of wire delay is considered.