Simulation of a ring oscillator operation during γ-ray irradiation using the TID response model of MOSFETs and its experimental verification

The response of N-type MOSFET characteristics to TID (Total Ionizing Dose) effects caused by γ -ray irradiation was modeled as a sum of two exponential functions which expresses the charge accumulation of the oxide traps and the interface traps respectively. This model was applied to the circuit simulation of a ring oscillator operation. It was shown that the simulation result reproduces the variation in the measured oscillation frequency experimentally. The simulation also showed that there is an optimum size ratio between N-type MOSFET and P-type MOSFET which can minimize the variation in oscillation frequency due to TID effects. These obtained results verified that the proposed method can be applied to the prediction of response in a dynamic operation circuit to TID effects.