Auto-tracking write and read processes for multi-bit-per-cell non-volatile memories
US6094368A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 4, 1999 |
| Grant date | Jul 25, 2000 |
| Priority date | — |
| Expiry date | Mar 4, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/22
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A multi-bit-per-cell memory includes a memory array having reference cells and storage cells, a read circuit, a content addressable memory, and an encoder. When data is written to the memory, a set of reference values for the write are written to the reference cells. The reference values correspond to the multi-bit digital values that can be stored in a single storage cell. For a read operation, the read circuit reads the reference values from the reference cells and stores the reference values in the content addressable memory. The read circuit then reads a data value from a storage cell associated with the reference values and applies the value read to the content addressable memory for a match operation. The output data is equal to the number or address of the entry containing the reference value that matches the data value. Since the reference and data values are written at approximately the same time and read at approximately the same time, any variations in the reference cells performance automatically tracks the performance of the storage cell. Thus, the output data value is correct even though the values that the read circuit reads from the reference and storage cells vary …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.