Adjusting resistive memory write driver strength based on a mimic resistive memory write operation

Patent metadata

Field	Value
Publication number	US-9583170-B2
Application number	US-201514620487-A
Country	US
Kind code	B2
Filing date	Feb 12, 2015
Priority date	Feb 12, 2015
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

Abstract

Aspects of adjusting resistive memory write driver strength based on a mimic resistive memory write operation are disclosed. In one aspect, a write driver adjustment circuit is provided to adjust a write current provided by a write driver to a resistive memory for write operations. The write driver adjustment circuit includes a mimic write driver configured to provide a mimic write current that mimics the write current provided to the resistive memory. The mimic write current is applied to a mimic resistive memory that contains mimic resistive memory elements that mimic a resistance distribution of the resistive memory. When the mimic write current is applied, a mimic voltage is generated across the mimic resistive memory elements. The write driver adjustment circuit is configured to adjust the write current based on the mimic voltage so that the write current is sufficient for write operations, but low enough to reduce breakdown.

First claim

What is claimed is:

1. A write driver adjustment circuit for adjusting a write current for a resistive memory, comprising:
a mimic write driver circuit configured to provide a mimic write current mimicking the write current provided by a write driver to the resistive memory;
a mimic resistive memory having a mimic resistance corresponding to a resistance of the resistive memory; and
a write driver control circuit configured to:
determine a mimic voltage generated across the mimic resistive memory in response to the mimic resistive memory receiving the mimic write current;
compare the determined mimic voltage to a threshold voltage; and
adjust the write current provided by the write driver to the resistive memory based on the comparison of the mimic voltage to the threshold voltage.

2. The write driver adjustment circuit of claim 1 , wherein the threshold voltage is equal to a breakdown voltage that, when present across a resistive memory element in the resistive memory, prevents the resistive memory element from storing a data value.

3. The write driver adjustment circuit of claim 1 , wherein the threshold voltage is in a range of a maximum threshold voltage and a minimum threshold voltage, wherein voltages greater than the maximum threshold voltage and less than the minimum threshold voltage correspond to the write current that causes a write failure in the resistive memory.

4. The write driver adjustment circuit of claim 3 , wherein the write driver control circuit is configured to adjust the write current by being configured to decrease the write current if the mimic voltage is greater than the maximum threshold voltage based on a reference voltage.

5. The write driver adjustment circuit of claim 3 , wherein the write driver control circuit is configured to adjust the write current by being configured to increase the write current if the mimic voltage is less than the minimum threshold voltage based on a reference voltage.

6. The write driver adjustment circuit of claim 1 , wherein the write driver control circuit is further configured to adjust the mimic write current provided by a mimic write driver to the mimic resistive memory based on the comparison of the mimic voltage to the threshold voltage.

7. The write driver adjustment circuit of claim 6 , wherein the write driver control circuit is configured to adjust the mimic write current by being configured to provide a mimic write driver strength control signal to the mimic write driver.

8. The write driver adjustment circuit of claim 1 , wherein the write driver control circuit is configured to adjust the write current by being configured to provide a write driver strength control signal to the write driver.

9. The write driver adjustment circuit of claim 1 , wherein the mimic resistive memory comprises a plurality of mimic resistive memory elements.

10. The write driver adjustment circuit of claim 9 , wherein the plurality of mimic resistive memory elements is configured so that the mimic resistance of the plurality of mimic resistive memory elements is approximately equal to an average resistance of the plurality of mimic resistive memory elements.

11. The write driver adjustment circuit of claim 1 , wherein the write driver control circuit is further configured to update the write current if the resistive memory is in an idle state.

12. The write driver adjustment circuit of claim 1 , wherein the write driver control circuit is configured to determine the mimic voltage by being configured to determine a difference of a first voltage at a first node of the mimic resistive memory and a second voltage at a second node of the mimic resistive memory.

13. The write driver adjustment circuit of claim 12 , wherein the write driver control circuit is further configured to:
receive the first voltage from the first node of the mimic resistive memory; and
receive the second voltage from the second node of the mimic resistive memory.

14. The write driver adjustment circuit of claim 13 , wherein:
the write driver control circuit is further configured to:
generate a maximum threshold voltage and a minimum threshold voltage based on a reference voltage;
provide a write driver strength control signal to the resistive memory based on a high indicator and a low indicator; and
provide a mimic write driver strength control signal to the mimic resistive memory based on the high indicator and the low indicator; and

the write driver control circuit comprises:
a buffer configured to provide the second voltage received from the second node of the mimic resistive memory;
a high voltage comparator configured to:
compare the first voltage to a maximum allowed voltage equal to a sum of the maximum threshold voltage and the second voltage; and
provide the high indicator indicative of whether the first voltage exceeds the maximum allowed voltage; and

a low voltage comparator configured to:
compare the first voltage to a minimum allowed voltage equal to a sum of the minimum threshold voltage and the second voltage; and
provide the low indicator indicative of whether the first voltage exceeds the minimum allowed voltage.

15. The write driver adjustment circuit of claim 14 , further comprising:
a minimum mimic write driver circuit configured to provide a minimum write current to perform a write operation in a minimum mimic resistive memory; and
the minimum mimic resistive memory configured to provide a minimum first voltage from a first node of the minimum mimic resistive memory.

16. The write driver adjustment circuit of claim 15 , wherein the low voltage comparator is further configured to:
compare the first voltage to the minimum first voltage; and
provide the low indicator indicative of whether the first voltage exceeds the minimum first voltage.

17. The write driver adjustment circuit of claim 1 , wherein the mimic resistive memory comprises a plurality of mimic resistive memory elements, wherein each mimic resistive memory element of the plurality of mimic resistive memory elements comprises a magnetic tunnel junction (MTJ).

18. The write driver adjustment circuit of claim 1 integrated into an integrated circuit (IC).

19. The write driver adjustment circuit of claim 1 integrated into a device selected from the group consisting of: a set top box; an entertainment unit; a navigation device; a communications device; a fixed location data unit; a mobile location data unit; a mobile phone; a cellular phone; a computer; a portable computer; a desktop computer; a personal digital assistant (PDA); a monitor; a computer monitor; a television; a tuner; a radio; a satellite radio; a music player; a digital music player; a portable music player; a digital video player; a video player; a digital video disc (DVD) player; and a portable digital video player.

20. A write driver adjustment circuit for adjusting a write current for a resistive memory, comprising:
a means for providing a mimic write current that mimics the write current provided by a write driver to the resistive memory to a mimic resistive memory to perform a mimic write operation;
a means for determining a mimic voltage generated across the mimic resistive memory in response to the mimic resistive memory receiving the mimic write current;
a means for comparing the mimic voltage to a threshold voltage; and
a means for adjusting the write current provided by the write driver to the resistive memory based on comparing the mimic voltage to the threshold voltage.

21. A method of ad

Assignees

• Qualcomm Inc

Inventors

• Kim Taehyun
• Kim Jung Pill
• Kim Sungryul

Classifications

• G11C11/1675 Primary

  Writing or programming circuits or methods · CPC title

• G11C11/1677

  Verifying circuits or methods · CPC title

• G11C2013/0078

  Write using current through the cell · CPC title