Non-volatile semiconductor memory device conducting read operation using a reference cell
AssigneeRenesas Technology Corp.
InventorTsukasa Ooishi
Life of this patent
Estimating the term…
Abstract
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.
Claims15
A non-volatile semiconductor memory device, comprising:
- a plurality of memory cells each storing data in a non-volatile manner;
- a reference cell which is compared with a selected memory cell of said plurality of memory cells in read operation;
- a spare reference cell having same characteristics as those of said reference cell, and provided as a spare of said reference cell;
- a reference cell selecting section for selecting one of said reference cell and said spare reference cell in said read operation;
- and
- a data read circuit for reading storage data of said selected memory cell based on access to said one of said reference cell and said spare reference cell which is selected by said reference cell selecting section and access to said selected memory cell, wherein said reference cell selecting section is capable of switching selection of said reference cell and said spare reference cell according to conditions.
A non-volatile semiconductor memory device, comprising:
- a plurality of memory cells each storing data in a non-volatile manner;
- a plurality of reference cells which are compared with a selected memory cell of said plurality of memory cells in read operation;
- and
- a data read circuit for reading storage data of said selected memory cell based on access to said selected memory cell and access to at least two of said plurality of reference cells in said read operation.
A non-volatile semiconductor memory device, comprising:
- a plurality of memory cells each storing data in a non-volatile manner;
- a reference cell which is compared with a selected memory cell of said plurality of memory cells in read operation;
- a data read circuit for reading storage data of said selected memory cell based on access to said reference cell and access to said selected memory cell in said read operation in normal operation;
- and
- a reference cell test section for testing said reference cell in operation test other than said normal operation.
Dependencies are inferred from the claim text.