BUILT IN SELF TEST AND BUILT IN SELF REPAIR SYSTEM

摘要

A RAM test and fail repair system is provided to test a RAM with an automatically generated test pattern by adding a BIST(Built In Self Test) and a BISR(Built In Self Repair) circuit in a device and to repair fail bits into normal bits. According to a RAM(Random Access Memory) test and fail repair system, a first operating part(100) includes a RAM(110), an internal register(120) and a fail treatment part(130). The RAM comprises a main RAM and a redundancy cell. The internal register stores a fail address and a good redundancy address. The fail treatment part stores fail address and good redundancy address in the internal register by comparing a test pattern written in the RAM with a test pattern through an internal comparator. A second operating part(200) comprises a RAM address counter(210) generated addresses to access a RAM cell and a comparator(220) comparing the address generated in the RAM address counter with a fail address.