Techniques for fast electro-thermal simulation of ICs

An approach to electrothermal simulation in which SPICE3 provides a framework as the nonlinear electrical simulator is described. For long-term reliability determinations in which DC and steady-state simulations are appropriate, the proposed thermal simulator uses the iterative incomplete Coleski/conjugate gradient (ICCG) optimization technique. For determining electrothermal interactions in which transient thermal simulation is appropriate, the simulator uses a macromodeling technique. Since SPICE3 uses modified nodal analysis, an admittance (Y-) parameter representation for the macromodel of the thermal circuit is formed. The speed advantages gained using these thermal and electrical thermal simulation techniques depend on the total number of thermal nodes in the circuit. Two orders improvement are obtained with circuits of about 10000 nodes.<>