Portable Behavioral Modeling of TID Degradation of Voltage Feedback Op-Amps

Abstract

Presently the tools available for predicting the effect of radiation on microelectronic circuits rely on SPICE models to simulate post-irradiation parameter and performance changes. However, modeling complex integrated circuits with SPICE simulations requires large amounts of engineering and computer simulation time. Also, repetitive simulations are needed with SPICE to simulate the evolution of degradation in the circuit parameters with total dose. Behavioral modeling technique provides an excellent alternative. Simplified behavioral models of a circuit or a sub-circuit could replace the SPICE-based circuits. The behavioral models describe the electrical circuit behavior and its dependence on the radiation dose with a high degree of accuracy. A single continuous simulation could ideally cover the entire circuit response from normal electrical operation (pre-irradiation or pre-rad) to post-irradiation performance at different exposure levels to assess system failure or to qualify radiation tolerance. This thesis describes a generic modeling technique to create TID aware behavioral models of voltage feedback op-amps without creation of underlying SPICE micro-model. The op amp behaviors dependence on supply voltage, input voltage and total dose are captured in the model. The model accurately predicts TID response of board-level designs without expensive fabrication runs. The behavioral model runs at least 79 times faster than SPICE in the case of Schmitt trigger oscillator circuit while maintaining accuracy to within 5% of SPICE values.