Exact and approximate estimation for maximum instantaneous current of CMOS circuits

We present an integer-linear-programming-based approach for estimating the maximum instantaneous current through the power supply lines for CMOS circuits. It produces the exact solutions for the maximum instantaneous current for small circuits, and tight upper bounds for large circuits. We formulate the maximum instantaneous current estimation problem as an integer linear programming (ILP) problem, and solve the corresponding ILP formulae to obtain the exact solution. For large circuits we propose to partition the circuits, and apply our ILP-based approach for each sub-circuit. The sum of the exact solutions of all sub-circuits provides an upper bound of the exact solution for the entire circuit. Our experimental results show that the upper bounds produced by our approach combined with the lower bounds produced by a genetic-algorithm-based approach confine the exact solution to a small range.