Computer simulation of magnetic bubble logic devices

Abstract

Operation margins for a dual-conductor current access magnetic bubble AND/OR gate, a one-bit full adder and a string comparator were simulated by a computer program. These gates employ bubble-bubble interaction to perform logic functions. A bubble replicator using a third layer conductor was also simulated. For the same lithographic feature size, the comparator requires 4.5% the area of the same function implemented in silicon. The simulation procedure is based on the Hayashi method where the bubble domain wall is divided into 18 to 72 wall segments which move according to the total effective field at the center of each wall segment. The field at every point is calculated by a finite difference routine. The logic functions simulated exhibited a 40-Oe bias margin when the drive current is 1.6 mA/μm.