Compact modeling of environmentally induced radiation effects on electrical devices

This paper presents the feasibility of formalizing a compact modeling methodology for environmentally induced radiation effects, and of implementing that methodology into the Paragon compact modeling tool. For demonstration purposes, the paper focuses on two specific radiation effects implemented in a MOSFET device model. These two effects were chosen in order to illustrate two differing forms of model development. The first form takes existing device models and modifies the equations and/or variables already existing within that model to achieve the required results (behavioral modification). The second form adds completely new equations and variables to existing device models (behavioral augmentation). The MOSFET (1) threshold voltage shift due to total ionizing dosage (TID) and (2) leakage current increase due to TID, are two major device effects that fulfill both of these requirements. Voltage shift and leakage current are critical design issues in rad-hard electronics and space environments. The threshold voltage shift effects are implemented through the modification of device model equations, while leakage current increases are implemented with added behavioral macros to the model topology, thus fulfilling the second requirement. The use of the modified compact MOSFET model is illustrated in the simulation of an op-amp based filter. Gain and frequency shifts can be observed and compared as the circuit absorbs differing amounts of TID.