REDUNDANCY CIRCUIT USING ANTI-FUSE AND METHOD FOR RETRIEVING DEFECTIVE ADDRESS IN SEMICONDUCTOR MEMORY

摘要

PROBLEM TO BE SOLVED: To provide a redundancy circuit, in which a fuse program state is precisely discriminated without depending on variation of a destruction state of a fuse. SOLUTION: This redundancy circuit has first and second electric fuses, a differential amplifier, a storage circuit, and a switching circuit. Electric characteristics of the first and second electric fuses are varied by applying voltage of some level or more. The differential amplifier receives two signal voltages depending on difference between respective current characteristics of the first and second electric fuses, amplifies the difference of these signal voltages, and outputs it. The storage circuit stores an output from the differential amplifier. The switching circuit makes a state between the differential amplifier and the storage circuit either state of a connected state or a cut-off state.