Adjoint transient sensitivity computation in piecewise linear simulation

This paper presents a general method for computing transient sensitivities using the adjoint method in event driven simulation algorithms that employ piecewise linear device models. Sensitivity information provides first order assessment of circuit variability with respect to design variables and parasitics. This information is particularly useful for noise stability analysis, timing rule generation, and circuit optimization. Techniques for incorporating adjoint transient sensitivity into ACES, a general piecewise linear simulator, are presented. Sensitivity computation includes algorithms to handle instantaneous charge redistribution due to the discontinuous conductance models of the piecewise linear elements, and the loss of simulation accuracy due to the non-monotonous responses in autonomous adjoint circuits with non-zero initial conditions. Results demonstrate the efficiency and accuracy of the proposed techniques.