Non-volatile semiconductor memory device conducting read operation using a reference cell

摘要

A spare reference cell is provided for a reference cell which is compared to a selected memory cell in read operation. A data read circuit reads storage data of a selected memory cell based on access to the selected memory cell and access to a selected one of the reference cell and the spare reference cell. Selection of the reference cell and the spare reference cell is not fixed according to the result of operation test conducted before a device is used, but can be switched according to various conditions.