System for testing a group of functionally independent memories and for replacing failing memory words
View Patent ↗System for testing a group of functionally independent memories ( 102 ) and for replacing failing memory words of the group of functionally independent memories ( 102 ) by redundant memory words, comprising: redundancy means 108 ) including at least one array of redundant memory words ( 108 a ) and address registers ( 108 b ) connected to at least one array of redundant memory words ( 108 a ); a test means ( 114 ); a group of first multiplexers ( 110 ) following the test means ( 114 ) and preceding the memories ( 102 ) and the at least one array of redundant memory words ( 108 a ); and a group of second multiplexers ( 112 ) following the memories ( 102 ) and the at least one array of redundant memory words ( 108 a ), wherein each second multiplexer ( 112 ) is connectable to the test means ( 114 ).
1. System for testing a group of functionally independent memories and for replacing failing memory words of said group of functionally independent memories by redundant memory words, comprising:
(a) a redundancy means including at least one array of redundant memory words and address registers connected to said at least one array of redundant memory words for storing and retrieving addresses of failing memory words;
(b) a test means including a test data output, a test address output, and a read/write output for providing test data, test addresses and read/write signals to each memory of said group of functionally independent memories;
(c) a group of first multiplexers for respectively either connecting said test data output, said test address output, and said read/write output of said test means or a respective functional data/address/read/write input to a respective data/address/read/write input of an associated memory and to a respective data/address/read/write input of said at least one array of redundant memory words; and
(d) a group of second multiplexers for respectively either connecting a respective memory data output of an associated memory or a respective redundancy data output of said at least one array of redundant memory words to a data output of a respective second multiplexer, wherein said data output of each second multiplexer is connectable to a data input of said test means for receiving data from each memory of said group of functionally independent memories.
2. System according to claim 1 , wherein said test means including a test controller for at least generating test data and test address data, and an address transcoder for decoding test addresses of a test address space generated by said test controller into addresses of said memories.
3. System according to claim 1 , wherein said system includes a data multiplexer comprising a plurality of data inputs respectively connected to said data outputs of said group of second multiplexers, and a data output connected to said data input of said test means.
4. System according to claim 1 , wherein said redundancy means comprises plural arrays of redundant memory words, wherein each array is spatially and functionally associated to a respective memory of said group of functionally independent memories.
5. System according to claim 1 , wherein said address registers of said redundancy means are connected to fuse boxes comprising fuses to permanently store the addresses of failing memory words.
6. System according to claim 1 , wherein said group of functionally independent memories is a group of static random access memories (SRAM).
7. System according to claim 1 , wherein said test means is a built-in self test means.