A COMPLETE RADIATION RELIABILITY SOFTWARE SIMULATOR

In this paper we describe a simulator which can be used to study the e ffects on circuit behavior of two radiation phenomena: Single Event Up set (SEU) and total-dose radiation effects. Using this simulator the u ser can predict the error rate in large circuits due to single event u pset. The error rate model described here uses a well established meth odology, but for the first time a different choice is made on picking up the sensitive nodes, enabling a quick prediction even for very comp lex circuits. The simulator predicts circuit behavior after total-dose irradiation using as inputs: the dose rate and the total dose, parame ter sets that characterize-the transistor response to radiation, and t he circuit netlist. The total-dose simulator is based on physical mode ls of the changes in the MOSFET caused by radiation. We quantify the d egradation of each MOSFET in a circuit with two parameters and determi ne the change in the MOSFET characteristics from preirradiation MOSFET data. Using the ''irradiated'' MOSFET parameters, we can simulate cir cuit behavior using an ordinary circuit simulator such as SPICE. With this simulator, one can study how resistant a circuit is to changes du e to irradiation and design circuits to be functionally radiation ''ha rd''. The ''double-kink'' in the MOSFET subthreshold region due to the parasitic effect of the edge transistors can be simulated and the use r is advised when leakage current unacceptably large. The speed degrad ation of a ring oscillator was simulated and the results compared with actual measured data.