MULTIPLE REPAIR SIZE REDUNDANCY

摘要

PURPOSE: A random access memory including a redundancy scheme is provided to reduce the number of fuses necessary for programming redundant memory array units without reducing chip yield and repairable defects. CONSTITUTION: In two patch redundancy selection circuits for selecting between lines in a pair of replacement lines(122) and one of four lines of a four line patch group(124), Programmed decoder(130) selects the pair of replacement lines and address line A0 selects individual lines of the pair by selecting the appropriate output of 1:2 demultiplexor(132). Programmed decoder(134) selects the group of four replacement lines and address lines A0 and A1 select individual lines of the group by driving the appropriate output of 2:4 demultiplexor(136). Accordingly, a group of 8 redundant elements is selected using an appropriate decoder and with A2, A1 and A0 selecting an appropriate output of a 3:8 demultiplexor.