Improved algorithm for computing all the DC operating points of diode-transistor circuits

The paper deals with the circuits containing diodes and bipolar transistors, having multiple DC solutions. A method for finding bounds on the location of all the solutions is developed. The method exploits some monotonic operators and generates two sequences bounding the solutions from below and above. The sequences are convergent and their limits are the bounds on all the DC solutions. The method has been implemented as a preliminary procedure of an earlier developed algorithm for finding all the solutions, based on the idea of successive contraction, division and elimination of some hyperrectangular regions, where the solutions are sought. Numerical examples show that the proposed approach is efficient and improves the analysis of transistor circuits having multiple DC solutions. It is illustrated via two numerical examples.