# Memory Testing Algorithm

• View
12

0

Embed Size (px)

DESCRIPTION

PPT

### Text of Memory Testing Algorithm

• 5/22/2018 Memory Testing Algorithm

1/50

Memory Fault Models and

Testing Algorithms

Hardik Doshi

• 5/22/2018 Memory Testing Algorithm

2/50

Memory Functional Faults

Stuck at Faults (SAF)

Transition Faults (TF)

Coupling Faults (CF) Neighborhood Pattern Sensitive Faults (NPSF)

2

• 5/22/2018 Memory Testing Algorithm

3/50

Stuck at Faults (SAF)

The logic value of a cell or line is stuck at always 0 or 1.

Stuck at 0 (SA0) If stuck at always is 0 logic value.

Stuck at 1 (SA1) if stuck at always is 1 logic value.

From each cell, a 0 and 1 must be read.

3

• 5/22/2018 Memory Testing Algorithm

4/50

Stuck at Fault

4

• 5/22/2018 Memory Testing Algorithm

5/50

Transition Fault (TF)

A special case of SAF is Transition Fault (TF).

A cell or line which fails to undergo a from 0 to 1 when it is

written is said to contain an up transition fault .

A cell or line which fails to undergo a from 1 to 0 when it is

written is said to contain an down transition fault.

Each cell must undergo a transition and a transition, andbe read after each transition before any further transitions.

5

• 5/22/2018 Memory Testing Algorithm

6/50

Transition Fault (TF)

6

transition fault

• 5/22/2018 Memory Testing Algorithm

7/50

Coupling Faults (CF)

Write Operation which transits or in one cellchanges the contents of a second cell.

Ci coupled to Cj means that an transition incell j causes or transition in cell i.

Inversion Coupling Faults (Cfin)

Idempotent Coupling Faults (Cfid)

Bridging and State Coupling Faults

7

• 5/22/2018 Memory Testing Algorithm

8/50

State Transition Diagram of Two Good

Cells, iand j

8

Sij represent the state of cell i and j.

• 5/22/2018 Memory Testing Algorithm

9/50

Inversion & Idempotent Coupling Faults

An or transition in one cell inverts thecontents of the second cell is called inversion

coupling cell (Cfin).

Ci is coupled to Cj means transition inCj inverts the content of the Ci.

Ci Cj coupled to Cj means transition inCj inverts the content of the Ci.

9

• 5/22/2018 Memory Testing Algorithm

10/50

Inversion Coupling Cfin

Sij represent the state of cell i and j

10

• 5/22/2018 Memory Testing Algorithm

11/50

Coupling Fault (CF)

A CF is called Asymmetric fault when the coupled cell only undergoes from0 to 1 or a 1 to 0 transition due to fault.

A CF is called Symmetric fault when the coupled cell undergo both from 0 to1 and from 1 to 0 due to fault.

The Cfid is asymmetric fault and the Cfin is a symmetric fault.

A CF is called one way CF if the CF is sensitized only upon one transition ofthe coupling cell.

A CF is called two way CF if the CF is sensitized upon either transition of thecoupling cell.

Single Cfid is a one way, asymmetric CF.

Combination of the Cfids and is a two way asymmetric CF. 11

• 5/22/2018 Memory Testing Algorithm

12/50

Idempotent Coupling Fault(Cifd)

An or transition in one cell force thecontents of the second cell to a particular

value 0 or 1 is called inversion coupling cell

(Cfid).

Ci is coupled to cj means transition in cell j would make 0 in cell i.

Ci Cj , Ci Cj, Ci Cj12

• 5/22/2018 Memory Testing Algorithm

13/50

Idempotent Coupling Fault Cfid

Sij represent the state of cell i and j

13

• 5/22/2018 Memory Testing Algorithm

14/50

Neighborhood Pattern Sensitive Faults(NPSF)

The content of a cell is influenced by the contents of all other cells in thememory. The content consists of a pattern of 0s and 1s, or changes inthese contents.

Its also considered as K-coupling fault.

Active NPSF

Passive NPSF

Static NPSF

Memory Array

b : Base cell

d : Deleted Neighborhood cell

b+d : Neighborhood

14

d

d b d

d

• 5/22/2018 Memory Testing Algorithm

15/50

Active NPSF

The base cell changes its contents due to a change in the

deleted neighborhood pattern.

This transition is in only one deleted neighbor cell whileother neighbor and bas cell contain a certain pattern.

Example Ci,j

where Ci,j is location of base cell.

15

• 5/22/2018 Memory Testing Algorithm

16/50

Passive & Static NPSF (PNPSF & SNPSF)

The content of the base cell cant be changed due tocertain deleted neighborhood pattern.(PNPSF)

The content of the base cell is forced to certain state dueto certain deleted neighborhood pattern.(SNPSF)

Ci,j < 0,0,1,1; /x >

Ci,j < 0,1,0,0; -/0 >

16

• 5/22/2018 Memory Testing Algorithm

17/50

Fault 1 Ax

Fault 2 Cx

Fault 3 Cx

Ay Cy

Fault 4 AxAy Cx

17

• 5/22/2018 Memory Testing Algorithm

18/50

Fault A:- (1+2) Ax Cx

Fault B:- (1+3) Ax Cx

Ay Ay Fault C:- (2+4) Ax Cx

Ay Cy

Fault D:- (3+4) Ax Cx

Ay Cy

18

• 5/22/2018 Memory Testing Algorithm

19/50

Condition for detection AF

The in a march element indicates thepresence of read or write operations.

1. (rx,,wx)

2. (rx,,wx)

19

• 5/22/2018 Memory Testing Algorithm

20/50

When the fault may influence the behavior of the other

When the fault does not influence the behavior of otherfaults called Unlinked Faults.

SAF linked with TFs and CFs

20

• 5/22/2018 Memory Testing Algorithm

21/50

Zero-One

(w0);(r0);(w1);(r1);

This test algorithm has minimum set to detect

the fault

All SAFs are detectable.

TF is not detectable.

CFs , and are not detectable.

Not all Afs are detectable.

21

• 5/22/2018 Memory Testing Algorithm

22/50

Checkerboard

22

Cells are divided in two groups cell-1 & cell-2.

0s and 1s are written alternate pattern and make the

checkerboard pattern.

All SAFs are detectable.

Not all Afs ,TFs and CFs are detectable.

Mainly used for sleeping sickness in DRAM chip.

Pattern 1 Pattern 2

1 0 1 0

0 1 0 1

1 0 1 0

0 1 0 1

0 1 0 1

1 0 1 0

0 1 0 1

1 0 1 0

• 5/22/2018 Memory Testing Algorithm

23/50

Walking 1/0

Memory is filled with 0s(or 1s) except for the base-cell, whichcontains 1(respectively a 0).

During Test, the base cell walks through the memory.

All cells read with the base cell last.

All Afs, SAF, TFs, Coupling faults are detectable.

0 0 0 0

0 1 0 0

0 0 0 0

0 0 0 0

23

• 5/22/2018 Memory Testing Algorithm

24/50

GALPAT

Memory is filled with 0s(or 1s) except for the base-cell,which contains 1(respectively a 0).

During Test, the base cell walks through the memory.

0 0 0 0

0 1 0 0

0 0 0 0

0 0 0 0

24

• 5/22/2018 Memory Testing Algorithm

25/50

Sliding Diagonal

Uses diagonal of base cell instead of single base cell because eachcell has a different row and column address so that it checking the

row and column simultaneously.

Writes diagonal 1s to background of 0s. All memory cells are read,after which diagonal is shifted until all diagonal are not covered.

1 0 0 0 0 0 1 0

0 1 0 0 0 0 0 1

0 0 1 0 1 0 0 0

0 0 0 1 0 1 0 0

First Diagonal Third Diagonal

25

• 5/22/2018 Memory Testing Algorithm

26/50

MATS Algorithm MATS requires total 4*n operations.

(w0); (r0,w1); (r1) ;

M0 M1 M2

M0=(w0); M1=(r0,w1); M2=(r1);

M0:for :=0 to n-1 do

begin

A[i]:=0;

end; Same for M1 and M2;

Fault coverage is very poor not capable of detection of

Coupling Faults.

26

• 5/22/2018 Memory Testing Algorithm

27/50

Moving 1/0 Algorithm

(w0); (r0,w1,r1); (r1,w0,r0); (w1); (r1,w0,r0);(r0,w1,r1); Here ji (;) Operation Cj Ci

M5 on Cj r0 0 0

M5 on Cj w1 1 1

M5 on Cj r1 1 1

M5 on Ci r0 1 1

j

• 5/22/2018 Memory Testing Algorithm

28/50

MATS++ Algorithm

(w0);(r0,w1);(r1,w0,r0);

SAFs :- (M1) and (M2)

TFs :- (M1 and M2) and (M2) Afs are detected by given above conditions.

This algorithm cant detect any coupling faults.

28

• 5/22/2018 Memory Testing Algorithm

29/50

March X Algorithm

(w0);(r0,w1);(r1,w0)(r0);

All Afs are detected.

SAF :- (M1 or M3) and (M2)

TFs :- (M1 followed by M2) and (M2 followed by M3)

Cfin (ji) :- Ci Cj detected by M1 followed by M2

Ci Cj detected by M2 Idempotent faults ,(only when j

• 5/22/2018 Memory Testing Algorithm

30/50

March C- Algorithm

(w0);(r0,w1);(r1,w0);(r0,w1);(r1,w0);(r0);

Unlinked Idempotent Coupling Faults(Cfid), SAF, TFS, Cfin, Afs.

Ci Cj :- M3 followed by M4 and M1 followed by M2

Ci is coupled to Cj means transition in j cell causes

Recommended

Documents
Documents
Documents
Documents
Documents
Documents
Documents
Documents
Documents
Documents
Documents
Documents