A novel technique for the numerical extraction of equivalent circuits from physics-based device simulation is presented. The method is based on the partitioning of the device into functional regions, each corresponding to a circuit block. All the circuit elements have a clear physical interpretation. Element values are directly obtained from small-signal dc device simulation. The method generates equivalent circuits of a complexity similar to the traditional approach, with model generation times comparable with those of black-box and physics-based device models. Applications to one-dimensional pn junctions and bipolar transistors are presented, discussing the extraction algorithm in detail.