The quaternary interface technique in ECL integrated circuits

Abstract

The theory of differential current switches which applies to the design of multivalued ECL circuits is introduced. In this theory, the switching state of differential transistor pair and signal in ECL circuits are described by switching variables and quaternary signal variables, respectively. The connection operations between the two kinds of variables are introduced to describe the action process between switching element and signal in the circuits. Based on this theory, two kinds of interface circuits—2–4 encoder and 4-2 decoder are designed. The computer simulation for the designed circuits by using SPICE program confirms that both circuits have correct logic functions, desired DC transfer characteristics and transient characteristics. These interface circuits are compatible with binary circuits in the integrated process, the power supply equipment, the logic stage and the transient characteristic. Therefore, they can be used as inputoutput interface of the existing binary ECL integrated circuits so as to decrease the number of pins of a chip and the connections between chips.