Some two-transistor circuits possess more than three operating points

It has long been held that no more than three operating points can be possessed by any two-transistor circuit. This belief is based on a result proved for bipolar transistors that has been assumed to hold for field-effect transistors as well. In this paper a counterexample is given: A simple circuit containing two MOSFETs with realistic models that possesses five operating points is presented. The existence of such a circuit is justified by showing how the result mentioned above breaks down in the case of FETs