Describes a novel piecewise-linear simulation technique, which is classified between the previous switch-level simulation and the circuit (or timing) level one, for bipolar transistor circuits. In this method, a piecewise-linear model with a switch is adopted as a diode. Tracing the regions is carried out by the transition of the switch state patterns. First, the node voltages and the branch currents are obtained by solving the linear equation based on the modified nodal approach at each iteration. Based on these computation results, the switch state /sup z/k+1 at the next iteration is determined by the switch control which is defined as the consistent switching method. Iteration is repeated until /sup z/k+1=/sup z/k, namely, the switch state pattern converges. Since the plural switch states can alter simultaneously, efficient tracing can be performed. The authors apply the proposed algorithm to the DC analysis of bipolar digital circuits and show its availability.<<ETX>>