METHOD OF MAKING A MEMORY FAULT-TOLERANT USING A VARIABLE SIZE REDUNDANCY REPLACEMENT CONFIGURATION

摘要

A method of making a memory fault-tolerant through the use of a variable sizeredundancy replacement (VSRR) circuit arrangement. A redundancy array supportingthe primary arrays forming the memory includes a plurality of variable size redundancyunits (RUs), each of which encompassing a plurality of redundant elements (REs). Theredundant units (RUs) used for repairing faults in the memory are independentlycontrolled. All the redundancy elements (REs) within a repair unit are preferablyreplaced simultaneously. The redundancy elements (REs) in the redundancy unit (RU)are controlled by decoding address lines. The variable size that characterizes thisconfiguration makes it possible to choose the most effective redundancy unit (RU), andin particular, the one most closely fitting the size of the cluster of failures to be replaced.This method significantly reduces the overhead created by added redundancy elements(REs) and control circuitry, while improving the access speed and reducing powerconsumption.Fig. 4a