Analysis of diode-transistor circuits having multiple DC solutions

The paper deals with circuits containing diodes and the Ebers-Moll modeled bipolar transistors. The basic and still open question of finding multiple DC solutions is discussed. To find all the DC solutions the diodes are considered as ideal and a method having combinatorial nature is applied. The main achievements of the paper are new algorithms enabling us to discard a huge number of combinations of the diodes states immediately, without any solving of equations, or by performing a considerably reduced amount of computation. The method guarantees finding all the DC solutions of the idealized diode-transistor circuits. Next each of the obtained solutions is corrected by means of a controlled SPICE simulation. A numerical example of transistor circuit is presented showing the efficiency of the proposed approach.