VHDL-AMS Modeling of Total Ionizing Dose Radiation Effects on CMOS Mixed Signal Circuits

A hierarchical method for total dose effects simulation of large mixed signal circuits using VHDL-AMS is described. Simplified behavioral models (or macro-models) of small sub-circuits replace SPICE-level circuits. The behavioral models describe the electrical circuit behavior and its dependence on the radiation dose. The behavioral models of sub-circuits can be assembled into complex mixed signal circuits. As a result, the computational cost is reduced significantly compared to conventional SPICE-based methods. The VHDL-AMS method also allows bias-dependent total dose degradation to be coupled to the circuit and operational conditions. Simulation accuracy remains sufficient to determine critical performance metrics of the circuit as the circuit performance degrades with dose.