Resistive memory element sensing using averaging

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Nov 8, 2002 - (12) United States Patent ... patent is extended or adjusted under 35. U.S.C. 154(b) ... (74) Attorney, Agent, or Firm—Dickstein Shapiro Morin &.
US006822892B2

(12) United States Patent Baker

(54)

(10) Patent N0.: (45) Date of Patent:

Nov. 23, 2004

RESISTIVE MEMORY ELEMENT SENSING

6,128,239 A

USING AVERAGING

6,188,615 B1

2/2001 Perner et al. ..

6,243,034

B1

6/2001

6,317,375 6,317,376 6,385,111 6,396,329 6,504,750 6,697,444

B1 B1 B2 B1 B1 B1

2002/0117895 2002/0126524 2003/0151532 2003/0198075

A1 A1 A1 A1

(75) Inventor: R. Jacob Baker, Meridian, ID (US)

(73) Assignee: Micron Technology, Inc., Boise, ID

(Us) (*)

US 6,822,892 B2

Notice:

Subject to any disclaimer, the term of this patent is extended or adjusted under 35

U.S.C. 154(b) by 0 days.

(21) Appl. No.: 10/290,297

* 10/2000 P611161 ...................... .. 365/209 Regier

.. ... ... ...

. 365/189.01 . . . . . ..

11/2001 5/2002 Zerbe Perneret al. Tran

.

341/166

365/206 365/210 365/210 .. 327/336

1/2003

Baker ...... ..

2/2004 8/2002

IiZuka et al. .... .. 375/343 Kemp et al. ............. .. 307/10.1

365/148

9/2002 Sugibayashi et al. ..... .. 365/158 8/2003 10/2003

Chen et al. ......... .. Brown

341/120

..................... .. 365/145

* cited by examiner

(22) Filed:

Nov. 8, 2002

(65)

Prior Publication Data

Primary Examiner—AndreW Q. Tran (74) Attorney, Agent, or Firm—Dickstein Shapiro Morin & Oshinsky LLP

US 2003/0067797 A1 Apr. 10, 2003

(57)

ABSTRACT

Related US. Application Data 63

Continuation of aPP lication No. 09/938,617, ?led on Au g .

27, 2001, now Pat. No. 6,504,750. (51)

Int. C1.7 .............................................. .. G11C 11/21

(52)

us. Cl. ........... .. 365/148; 365/189.07; 365/189.09;

365/236; 365/233 (58)

Field of Search .......................... .. 365/148, 189.07,

365/189.09, 233, 236 (56)

U.S. PATENT DOCUMENTS *

5,801,652 A * 5,907,299 A

5,986,598 A 6,038,166 A

*

7/1994 Wu et al.

................. .. 365/170

9/1998 Gong 5/1999

11/1999 3/2000

resistive memory cell element to maintain a constant voltage across the resistive element. The charge reservoir is con

nected to the voltage supply to provide a current through the resistive element. The current source is connected to the

charge reservoir repeatedly supply a pulse of current to recharge the reservoir upon depletion of electronic charge

References Cited

5,329,480 A

A system for determining the logic state of a resistive memory cell element, for example an MRAM resistive cell element. The system includes a controlled voltage supply, an electronic charge reservoir, a current source, and a pulse counter. The controlled voltage supply is connected to the

Green et al. .............. .. 341/143

from the reservoir, and the pulse counter provides a count of the number of pulses supplied by the current source over a predetermined time. The count represents a logic state of the memory cell element.

3 Claims, 6 Drawing Sheets

500

U.S. Patent

Nov. 23, 2004

Sheet 1 0f 6

US 6,822,892 B2

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U.S. Patent

Nov. 23, 2004

Sheet 3 0f 6

US 6,822,892 B2

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Nov. 23, 2004

Sheet 6 6f 6

US 6,822,892 B2

FIG. 7 1200

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