MULTISTATE ANALOG AND DIGITAL INTEGRATED CIRCUITS

Abstract

Several independent physical phenomena in unipolar and bipolar semiconductor pn junction devices and integrated structures lead to voltage and current-controlled negative resistance without the use of external feedback. These include avalanche breakdown, quantum mechanical tunneling, and minority carrier storage. Two complementary types of negative resistances may be utilized as a basis for generating multistable energy levels. The number of stable states and their relative spacings can be readily varied. Without negative resistance interaction, M+1 stable states can be generated where M is the number of negative resistance devices involved. With negative resistance interactions, additional multistability occurs, resulting in a total number of (M+1) + (M-1)!stable states. S-S, N-N, and S-N interactions are analyzed. In the latter case, complementary negative resistances can be made to annihilate each other. Multistate tunnel and avalanche negative resistances have been made to occur in single devices resulting in tristable, quadristable and higher order energy levels. Variable radix counters, oscillators, frequency dividers, and high density memory elements have been fabricated both as hybrid and monolithic integrated circuits.