Radiation-degradation Analysis and a Circuit Performance Improvement Method for Optoelectronic Field Programmable Gate Array

A radiation-hardened optoelectronic field programmable gate array (FPGA) consisting of a holographic memory, a laser array, and a standard CMOS process programmable gate array VLSI has already been developed. The optoelectronic FPGA provides soft-error tolerance and can withstand an over 1 Grad total-ionizing-dose. However, the degradation of the optoelectronic FPGA is not small and cannot be neglected. Propagation delay and power consumption increase along with increasing total-ionizing-dose. This paper presents the degradation measurement results of an optoelectronic radiation-hardened FPGA and a method to improve its performance.

I. Introduction

Currently, damaged reactors and melted nuclear fuel at the Fukushima Daiichi nuclear power plant emit intense gamma radiation persistently. The maximum radiation intensity is reported to be 1000 Sv/h. Therefore, devices that are more radiation-hardened than space-grade VLSIs are necessary for the decommissioning of reactors and for the moving of melted nuclear fuel at the Fukushima Daiichi nuclear power plant [1],[2J. The total-ionizing-dose tolerances of currently available radiation-hardened VLSIs are insufficient for decommissioning and dismantlement operations [3]– [6]. In fact, the working durations of current radiation-hardened devices are limited to 10 hr.