Redundancy circuit for use in a semiconductor memory device

摘要

In order to replace defective cells, use is made of a normal decoder 20 and a redundant decoder containing address program devices RAPDO0 - RAPD1, RAPDi - RAPDi+1. The number of address program devices is made greater by 1 than that of the number of input address bits for selecting a row or a normal column. The input signals of the extra program device are complementary to those of one of the other program devices. Programs of the program devices include two steps for repairing defective cells. To increase the reliability of the redundancy, use is made in the program devices of a retentive memory element which is a retentive memory device of FLOTOX type with four bridge-connected cells. <IMAGE>