Variable write and read methods for resistive random access memory
View Patent ↗Variable write and read methods for resistance random access memory (RRAM) are disclosed. The methods include initializing a write sequence and verifying the resistance state of the RRAM cell. If a write pulse is needed, then two or more write pulses are applied through the RRAM cell to write the desired data state to the RRAM cell. Each subsequent write pulse has substantially the same or greater write pulse duration. Subsequent write pulses are applied to the RRAM cell until the RRAM cell is in the desired data state or until a predetermined number of write pulses have been applied to the RRAM cell. A read method is also disclosed where subsequent read pulses are applied through the RRAM cell until the read is successful or until a predetermined number of read pulses have been applied to the RRAM cell.
1. A variable read method for spin-transfer torque random access memory (STRAM), the method comprising:
applying two or more read pulses across an STRAM cell to read a desired data state of the STRAM cell, each read pulse has a substantially similar amplitude, and each subsequent read pulse has a duration and incrementing a counter by one for each read pulse application;
checking a read content from the STRAM cell, if the read is successful then the read method is complete, otherwise the applying step is repeated.
2. A method according to claim 1 , further comprising counting the number of read pulses applied across the STRAM cell, wherein the method continues until the read is successful.
3. A method according to claim 1 , further comprising counting the number of read pulses applied across the STRAM cell, wherein the method continues until the counter reaches a predetermined integer.
4. A method according to claim 1 , wherein each read pulse duration is determined by a look-up table.
5. A method according to claim 3 , further comprising generating an error code or flag if the counter reaches the predetermined integer.
6. A method according to claim 1 , wherein the checking step comprises utilizing an error correcting code.
7. A method according to claim 1 , wherein each read pulse duration is substantially similar duration.
8. A method according to claim 1 , wherein each read pulse duration is different.
9. A method according to claim 1 , wherein each subsequent read pulse duration is a first or second order function of the counter.
10. A variable read method for spin-transfer torque random access memory (STRAM), the method comprising:
applying two or more read pulses across an STRAM cell to read a desired data state of the STRAM cell, each read pulse has a substantially similar amplitude, and each subsequent read pulse has an increasing duration and incrementing a counter by one for each read pulse application;
checking a read content from the STRAM cell, if the read is successful then the read method is complete, otherwise the applying step is repeated.
11. A method according to claim 10 , further comprising counting the number of read pulses applied across the STRAM cell, wherein the method continues until the read is successful.
12. A method according to claim 10 , further comprising counting the number of read pulses applied across the STRAM cell, wherein the method continues until the counter reaches a predetermined integer.
13. A method according to claim 10 , wherein each read pulse duration is determined by a look-up table.
14. A method according to claim 12 , further comprising generating an error code or flag if the counter reaches the predetermined integer.
15. A method according to claim 10 , wherein the checking step comprises utilizing an error correcting code.
16. A method according to claim 10 , wherein each subsequent read pulse duration increases linearly.
17. A method according to claim 10 , wherein each subsequent read pulse duration is a first or second order function of the counter.
18. A method according to claim 10 , wherein each read pulse duration is different.