A New Classification of Path-Delay Fault Testability in ...

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Bushnell. International Institute o{Information Technology}Kolkata ... edu;bushnell@caip.rutgers ...... laborating with Intel Corporation,USA,and IRISA,.
维普资讯 http://www.cqvip.com Nov.2004,Vo1 . 19,No. 6,PP. 955 964 

J.Comput .Sci .& Technol  

A N ew Cl assi icati f on  of   Path- Del ay Faul t  Testabi l i t y  i n Term s  of   Stuck. at  Faul ts   Su bha s h i s   Ma j umde r  ,Bha r g a b  B.Bha t t a c ha r y a 。, Vi s hwan i   D.Agr a wa l 。 ,a nd   Mi c ha e l   L.Bus hne l l   I nt er nat i o nal   I ns t i t ut e  o {I n f or mat i on  Te c hnol o gy}Kol kat a  700091}I ndi a   。A  CM  Uni t Indi an St at i st i cal  Inst i t ut e,Kol kat a 7001   08,India  ,

De par t me nt   o{ECE,Aub ur n Uni v er s i t y}Al ab ama}AL  36849}U. S. A.  

De par t me nt   ol  ECE}Rut ge r s  Uni v e rs i t y}Pi s c at away}NJ  08855}U. S. A.   E— mai l :sml aj @vs n1 . c or n;bhar gab@i s i ca 1 . a l : . i n;va gr awal @e ng. aubur n. edu;bus hnel l @cai p. r ut ge r s . edu  Recei ved December  27,2002;revi sed M ay 14,2004.  

Abstract  

A new cl assi icati f on of   path— del ay f aul t  testabi l i t y i n a combi nati onal  ci rcui t  i s pres ' ented i n  terms  

of   tes tabi l i ty of  stuck—at  f aul ts i n an equi val ent  ci rcui t.Earl i er  resul ts  descri bi ng correl ati on of  path—del ay and  stuck—at  f aul ts  are  ei ther  i ncompl ete.or  us e a  compl ex model   of  equi val ent   ci rcui t   based on  ti mi ng  parameter s.It  

i s   s h o wn   he r e   t ha t   a   pa t h— d e l a y   f a ul t( r i s i n g   o r   f a l l i n g )i s   t e s t a b l e   i f   a n d   o n l y   i f   c e r t a i n   s i n g l e   o r   mu l t i pl e   s t uc k — a t   f aul t  i n  t he  equi val ent   ci rcui t  i s  testabl e.Thus.al l  a s pects  of   path— del ay f aul t s  rel ated  to t est abi l i t y  under  vari ous   cl s si a icati f on s chemes  can be i nterpreted usi ng t he stuck— at  f aul t  m odel  al one. The resul ts  uni f y most  of  the  exi s ti ng  concepts  and provi de  a bet ter  understandi ng of   path-del ay  f aul ts  i n l ogi c  ci r cui ts.   K eywords  del ay f aul t,f al se path,redundancy,stuck—at  f aul t  

i de nt i f yi ng unt e st abl e  pat h— del ay f aul t s  f rom t he  

1   I nt roducti on 

knowl e dge of  re dundant  s t uc k— at  f aul t s  i n t he   rcui t[ 1   I dent i 6cat i on  of   unt es t abl e  pat h— del ay  f aul ts   has   ci

.  

I t  was  obs er ved t hat  whi l e  s ome  

appl i cat i ons  t o  del a y  t es t i ng,t i mi ng  anal ys i s ,and  unt es t abl e  de l a y f aul t s  can be  eas i l y pre di ct e d  t i mi ng  opt i mi zat i on  of   di gi t al   ci r c ui t s.I n  t hi s   pa—   f r om t he l i s t  of  r e dundant  s t uc k— at  f aul t s ,ot he r   e  pat hs   do  not  c orr e spond t o  any  r edun—   per,we   es t abl i s h  a  s t rong  cor r el at i on  bet we en/ al se   untestabl

t i mi ng  pat hs  and r edundant  s t uc k— at  f aul t s  i n an  dant   s t uck— at   f aul t.I n  f ac t,t he r e  e xi s t   many  i r r e—   unf ol ded  ci rc ui t   obtai ned  f r om  t he   or i gi nal   ci r cul t   dunda nt   c i r cui t s   wi t h  unte s tabl e   pat h  de l ay  f aul t s.  

t hr ough s i mpl e  tr ans f or mat i ons. Pat h— del ay t es t —  

Se ver al  aut hor s  have  s ugges t ed c onst ruc t i on  of   i ng  has   t ur ned  out  t o  be  t he   mos t   acc ur at e   or f m  of   modi ied ci f r cui t s .whi c h pr es e r ve  t he  or i gi nal  s et   del ay  t es t i ng[  一  The  i mpor t ance   of   del ay  f aul t s   i s   of   paths  and c ont ai n  r edundant  st uck— at  f aul t s   on  .

f urt her   s t r engthened  by  t he   r ece nt   obs er vat i on  t hat   al l   unt es t abl e  pat hs.tam et   a1 . 【 1 J . J  cons t r uct ed  an 

many  def ect s   i n  the  deep— s ubmi c r on  r egi me   c annot   e xpanded f or m  of   c i rc ui t  graph known as  f e   dag   be  model ed by t he  cl as s i cal  s t uc k— at  f aul t s [ 4   J and  i n whi ch f anout s  ar e  pe rmi tt e d onl y at  t he  i nput   ,

t hat  many s pot  def ec t s  l i ke  opens  of te n pas s  t e st   nodes. Thi s  i s  done  by movi ng al l  f anout s  and  screens[ 5J Thes e  o pens   US Ual l y mani f es t  as  t i mi ng  al l  i nve rt e rs  t owar d t he  pr i mar y i nput s.The  s i z e  .

f aul t s  and  i mpr oved  t echni que s   of   del ay  f aul t   t es t —   of  t he  l eaf - dag mav  be  exponent i al  i n t he  si z e  of   i ng  ar e   needed[ 6 ] t he ci r cui t. The l eaf - dag i s  us ed t o i dent i f y t he  . 

The numbe r  of  pat hs  c an be  an expone nt i al   r obus t — dependent  pat hs.whi c h cor r es pond to  r e—   f unct i on  of   t he  number   of   l i nes   i n  t he   ci r cui t .How—   dundant  s t uc k— at  f aul t s.Gharaybeh e t  a1 . 【 l 4 J    pr o—   ever ,al l  pat hs  need not  be  te s t ed as  many pat hs   duced  a t wo- l evel   ci r c ui t  whe r e  each  or i gi nal  pat h  may be i nc apabl e  of  pr oduci ng t i mi ng  er r or s  i n  i s  expl i c i t l y r epr es ent ed. They us ed t he c i r c ui t   s pi t e   of   thei r   l ar ge  pr opagat i on  del ays[   These are  t o  gener at e  t es t s  f or   si ngl y- ・ t e st abl e  and mul ti pl y- .   .

est abl e  pat hs.Redundant   st uc k— at   f aul t s   i dent i f v   c a l l e d   f al s e   p at hs .Muc h   wo r k  ha s  be e n  do ne   on   t f a st  i dent i ic f at i on of   f al s e pat hs  i n c ombi nat i onal   t he  unt es t abl e   pat hs .   c i rc ui t sl 8, 圳 Thei r   i dent i ic f ati on i s   equal l y i mpor—   I n anot her  appr oach. Ghar aybeh e t  a1 . [ 1 4, 1 5 ]   .

t ant   i n  s equenti al  c i r cui t s[ 1  ̄ , 1 1 ] .  

us ed s i mul at i on t o s pl i t  ci r cui t  nodes  f or   s epar at —  

ng t es t ed and unt e s te d pat hs. The  s pl i t  c i rc ui t   Ma j umde r  e t  a 1 .  e x pl o r e d  t he  pos s i bi l i t y  o f  i Regul ar  Paper  

Thi s  wor k was  f unded i n  par t  by  M ot or ol a  I ndi a  El ect r oni cs  Ltd. ,Bangal or e  560042,I ndi a.   ” An  earl i er   vers i on  of   t hi s  paper   appear ed i n  the  Pr oceedi ngs   of   the  12t h  Int.Conf l VLSI  Des i gn.Jan.1999 

维普资讯 http://www.cqvip.com J.Comput.Sci.& Techno1. ,Nov.2004,Vo1. 19,No. 6 

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nput   s i de.and  changi ng  t he  gat e   t ypes   by  De—   c ontai ns   new  r e dundant   s t uck— at   f aul t s,whi c h  cor -   the i Mor gan’ s   l aw.I t   can  be  pr oved t hat  a  pat h- de l a y  r es pond  t o  t he   unt es t abl e   pat hs.  

aul t   i s   t es t abl e   i f   a  cor re s pondi ng  st uc k— at   f aul t   i s   I n  t hi s  wor k,we  es t abl i s h a one - t o- one  cor r e —   f e st abl e.The   work  on  l eaf - dag  di d  not   addr es s   t he   s pondence   bet ween  ever y  unt es t abl e   pat h  i n  a  com—   t i s s u e   o f   i n t e r p r e t i n g   v a r i o u s   f a u l t   c l s a s i i f c a t i o n s ; i n   bi nat i onal   c i rc ui t   C  and  a  r edundant   s t uck— at   f aul t   a ct.cl as s i icat f i ons  wer e not  known at  t hat  t i me.   i n a  ci r cui t  U obt ai ned by unf ol di ng  C acc or di ng  f I n   o u r   c a s e . we   a l l o w  t h e   u s e   o f   a l l   s i mp l e   g a t e s   i n   t o  cer t ai n  r ul es.For   s ever al   wel l - known  pat h- de l a y    wer e  pre s ent  i n  t he   ori gi nal   ci r cui t  C.   f aul t   cl as s i icat f i ons,we   t hen  c harac t er i ze   eac h  c l ss a   U that Gha r a y b e h   e t   a 1 . [  】p r e s e n t e d   a   t i g h t “ i f  and  i n  t er ms   of   te s tabi l i t y of   s t uc k— at  f aul t s   i n  t he  uI 卜 

onl y  i f ’ ’cor re s ponde nce   bet wee n  st uc k— at   f aul t   and 

f c I l ded c i r cui t.  

del ay f aul t  t e st abi l i t i e s. However,t hei r  t wo- l evel   e qui val ent   ci r c ui t s   ar e  c ompl ex  i nvol vi ng  t i mi ng  pa-  

2  Ci rcui t  U nf ol di ng 

r   me t e   r s _Ma j hi  e t   a 1 .   a n d  Ma j umde r   e t   a 1 . [ 1 2 】  

oved t hat  c ert ai n r edundant  s t uc k— at  f aul t s  i m-   I n or der  t o e s tabl i s h a one— t o— one r e l at i on  be —   pr y unt es t abi l i t y of  s ome  pat h- del ay f aul t s,but   t we en  e ve ry  pat h  i n  a  c i r c ui t  C  and  s ome  s t uc k— at   pl hi ng wa s  s ai d about  t he  conver s e. Spar mann  f aul t,we   unf ol d  t he   ci r cui t   f r om  eac h  f anout   poi nt   not Koe l l er[ 1 s ]c ons i der ed  t he  c l as si ic f at i on  done  by  except   t he  pr i mar y  i nput   f anout s .For   ever y  f anout   and   a1 . [  引 i n  t he   ci r cui t   ot her   t han  t he  f anout s   of   pr i mar y  i n-   Lam et



They  pr ove d  t hat  i f   a  pat h P i n a 

i rc ui t   i s   i nt e r nal l y  f anout   f r ee,and  i s   non- r obus t l y  put s,we  dupl i cat e  t he   s ubci r cui t   f e edi ng  t he   f anout   c u n t e s t a bl e , t h e n   a   s i n g l e   s t u c k — a t   f a u l t   a t   t h e   i n p u t   poi nt   so  t hat  e ac h  gat e  r ec ei vi ng i nput s   rom  f t hat   ine   of   P  i s   r edundant.Thus,t hei r   oC f US   wa s  on  t he  f anout   poi nt   has   a  s epar at e   subc i r cui t   c onnect e d  t o  f r se   cas e,whi c h  i s  use d  t o  r emove  f al s e  pat hs   i t s   i nput.W e  appl y  unf ol di ng  i n  t hi s   wa y  unt i l   al l   conve el i mi nat i ng  r edundant   st uc k—at   f aul t s .However,   gat es   i n  t he   ci r cui t   have   s i ngl e   f anout.I n  t he   wor st   by  ca se,t hi s   mi ght   r equi r e  an  expone nt i al   c ompl exi t y  no  gene ral  r e sul t  on  t he“i f   and  onl y i f”c ondi t i on 

but   st i l l   we  can  do  i t   at   l eas t  t heor et i cal l y  f or   any  bet ween re dundanc y of  s t uc k f aul t s  and unt st e a-   l i t y  of   path. de l ay f aul t s.i n  a  s i mpl e   or f m,s ee ms   c i r c ui t .Ho we v e r ,t hi s   e xpa ns i o n  o f   c i r c ui t   i s   j us t   bi an abst r act i on t hat  i s  us ed t o pr ove  our  cl ai ms.  

t o ha ve   been  known.The  pre s ent  work  makes   t he  

Fi g. 1   shows   t he  ori gi nal   ci r c ui t   C  and  t he   unf ol de d  f ol l owi ng  cont ri but i ons:   ci r cui t  U f or  an e xc l us i ve — or  f unct i on. I t  ma y be  

・“ i f   and  onl y  i f ”condi t i ons   ar e   pr e se nt ed  us i ng 

not ed  t hat   or f   ever y pat h  pr e se nt  i n  C,ther e  i s   a  a  si mpl e   equi va l ent  c i r cui t ;   c or re s pondi ng  pat h  i n  U and vi ce   ve r sa.Fur t her —  

・mul t i pl y— t es t abl e   pat hs   f def ined  l at e r1  ar e  de —  

more,ever y pat h i n U uni quel y c or r e sponds  t o a  s c ri bed  i n  t e r ms   of   mul t i pl e   s t uc k— at  f au lt s   or f  t he 

pr i ma r y   i n put( o r   on e   of   i t s   f a no ut   br a nc he s  i n  t he   i fr s t  t i me;   c a s e   i t   ha s   mul t i p l e   f an out s )an d  vi c e   ve r s a   a s   ea c h   ・var i ous   del ay  f aul t   cl s si a icat f i on s c heme s  l i ke  of   t he   gat es   i n  U  has   onl y  a  s i ngl e   f anout.W i t h  ev—   e ry  pat h  P  i n  C  we   as soci at e   t wo  st uck— at   f aul t s   on 

r o bus t — t e s t a bl e ,f unc t i ona l   s e n s t i z ab l e( FS) 【  J ,s i n-  

g l e  t e s t ab l e( ST) ,mul t i pl y  t e s t a bl e( MT) [ 1 4 , 2 0 】 ,   t he   p r i mar y   i nput   I F( o r   pos s i bl y   a   f a no ut   br a nc h)   pr i mi t i v e   s i ng l e   pa t h  d e l a y   f au l t( SPDF) , p r i mi t i ve   wher e  t he   cor r es pondi ng pat h功 i n  U  or i gi nat es .   mul t i — pat h  del ay  f aul t  f MPDF) [ 21 1  a re   i nt er pr et ed 

or F   a   r i s i ng( f a l l i ng)t r a ns i t i on   a t  t h e   i np ut   o f   P 

us i ng  t he  s t uck— at  f aul t  mode l  al one,on  t he   same  

we  c onsi der   t he   s t uc k— at 一 0( st uc k— at 一1)f aul t  on  I F  equi val ent   ci r cui t ;   s  a do ne   by   Ma   hi   e t   a 1 . _ l 6 1   a nd  Ma j umd e r   e t   a 1 . 【   2 1 .  

・ a uni ied and compl f et e  c har act er i zat i on of  

pat h. . de l a y f aul t s  i s  pr es ent e d  i n  t er ms   of   st uc k. . at   f aul t s.  

3  Stuck-at  Faul ts  i n  Unf ol ded Ci rcui t  and  Path  Cl assi icati f ons  

( a)  

( b)   Pat h— del ay f aul t s  have  been di vi ded i nt o di f -  

Fi g. 1.( a)Or i gi nal   c i r c ui t   C.( b)Unf ol de d   c i r c ui t   U 

f er ent  cl as se s  by var i ous  gr oups  wor ki ng i n de—  

ay f aul t  t e st i ng. The l at es t  summar y appear s   i n  An unf ol ded ci r cui t  i s  equi val ent  t o l eaf -   l Fi g . 2 [   。 一  1 dag[ 1 3   1 7 ] Ho The   def ini t i ons   and  meani ng  of   abbr e—   wever ,l eaf - dag   r equi r es   an  addi t i onal   .



ons  ar e   expl ai ned l at er .   st ep  of   pr e pr oce s si ng f or   movi ng t he   i nver s i ons  t o  viati

维普资讯 http://www.cqvip.com

Subha shi s   Ma jumde r  e t  a1 . :A  Ne w  Cl as si ic f at i o n  of   Pat h— Del a y  Fau l t  Tes t abi l i t y  Lam et  a1 .  

( I EEE —



on— RD 

TCAD’ 9 5)  

Cheng  and Chen 

957 

RD 

Robust   Non—r obust   Functi ona1   R

( I EEE TCAD’ 9 6)  

t e s t abl e  t e s t ab l e  



Ghar aybeh et  a1 .  

Si ngl y—t est abl e  

( J ETTA’ 97 )   Si var aman and Str oi wa s   .

( VLSI  De s i gn’ 97 )  

Pr i mi t i ve   SPDF 

s en s i t i za b1 e  

e dunda nt  

M ul ti pl y—   S  ngl y—t est abl e 

t e s t a bl e   d   e pe nde nt   Pr i mi t i ve   Pr i mi t i v e ~   MPDF  de pe nde nt  

Fi g. 2.Cl ass i icati f ons   of   pat h— del ay f aul t s  

Ghar ayb eh  e t  a1 . ’ s  Cl as s   疗c at i on[ 1 4 J .   I n t hi s  

pl i e d   at   t h e   pr i ma r y   i nput s   f  o t he   c o mpo ne nt   pa t hs ,  

c l as s i ic f at i on, pat hs  ar e gr ouped i nt o t hr ee  c at —  

a nd( i i )a l l   s i d e — i n put s   t o   t he   s e t   f  o pat h s   a r e   no n—  

egor i es :s i ngl y— t e st abl e,mul t i pl y—t es t abl e  and ST-  

c ont r ol l i ng  unde r  v2.  

de pe ndent .  

Let  us  cons i de r  t he ci r c ui t  of  Fi g. 1  agai n.   A 

De f i ni t i on 3. 1  r Funct i ona1 ) .   A pa t h  i s   s i ng l y— t e s t ab l e( S  f o r  a  de l a y   f au l t   a nd  o nl y  

phys i c af   pat h  i s   a  cont i nuous   s equence   of   gat e s   and 

l i ne s  s t art i ng f r om a pr i mar y i nput  t o s ome  pr i —   a t e st  guar ant e es  det e ct i on,gi ven t hat  i t  i s  t he   mar y  out put.A  l o gi c al   pat h  i s   a  physi cal   pat h  wi t h 

onl y  f aul t   pr e sent   i n t he  ci r cui t [ 1 4] .An  ST  pat h  i s   al so  cal l e d  a non— r obus t l y  t e st abl e   pat h.  

a   t r an s i t i on   di r e c t i on下( r i s i ng)o r   J ,( f a l l i ng )a t   i t s   i nput . Out  of   t he  t wel ve  l ogi cal  pat hs  i n t hi s   ci r —  

Def ini t i on 3. 2( St ruct ur a1 ) .   A pa t h  i s   cui t ,onl y t wo pat hs ,J ,1 - 3— 4— 6— 7  and J ,2 - 3— 5— 6— 7,     other   pat hs  ar e  ST.I n  t he   s i ng l y — t e s t ab l e( S  f o r  a   de l a y   f au 此t 厂a nd  o nl y   are ST—dependent.All t 厂t he r e   e x i s t s   a   v e c t o r - pa i r( V l , u2 )s uc h   t ha t :( i )a   unf ol ded ci rc ui t,t he  cor r es pondi ng  pat hs  ar e  J ,1 —   t r ansi t i on wi t h a ppr opr i at e  di r ec t i on i s  a ppl i e d at   3。 4— 6— 7  and  J ,2— 3r _ 5— 6— 7.The  s t uc k— at 一 1  f aul t s  on 

t he   pa t h   i nput ,a nd( i i )a l l   s i de — i nput s   o f   t he   pa t h  

t he  f anout   br anches   rom  f i nput  1  t o  gat e   3  f hence —  

ar e  non— c ont r ol l i ng  i n  v2.  

or f t h  denot ed  as  1 - 31   and  on  2— 3 ar e   r edundant  as  

I n t he  l i t e rat ur e,t he  same  condi t i ons  de ine f  a  shown  i n  Fi g. 3.Res t   of   t he   t en  s tuc k— at  f aul t s   ar e   non— r obus t  t e st   f or  a  pat h.  

al l   t es t abl e.The  t wo  r edundant   s t uc k. at   f aul t s   ar e  

BY def ini t i on.an ST pat h mus t  have  a non—   of   t he  t ype  und vab l e  f   a  f aul t  t hat  cannot  be  exo   r obust  del ay t e st .

However ,i t  i s  pos s i bl e  t o  ci t ed  and  pr opagat e d  t o  obs er vabl e   out put s   s i mul —  

have  t es t abl e  pat hs  t hat  ar e   not  ST.Some  s i ngl y-   t ane ousl y1 . Mai umde r  et  a1 .cor r ect l y pr edi c t ed  unt es tabl e   pat hs   can  be   t e st ed  i n  gr oups ,i . e. ,a  t es t   t he   unt es t abi l i t y  of   t he   t wo   paths   s pe ci ied  f above  i n  he   unf ol ded  ci rc ui t[ 1 2   J Her can  be  f ound  when  s ever al   pat hs   ar e   s i mul t ane ous l y  t e.we  es t abl i s h  t he  f act   .

f aul t y.W e  c al l   a gr oup mi ni mal   i f   r e moval  of   any  t hat  t e st abi l i t y of   any pat h— del ay  f aul t  i s   st r ongl y 

s i ngl e  pat h l eaves  t he   gr oup unt es tabl e.Consi der   r el at ed t o  t he   det e ct abi l i t y  of   s ome  s t uc k— at   f aul t s   t he   f ol l owi ng  cas es  f or   a  s i ngl y— unt e s tabl e   pat h  A.  

i n  t he   unf ol ded  ci rc ui t.For   a  pat h— del a y  f aul t   i n  a 

11  I f   any t e st abl e   mi ni mal   gr oup  of   pat hs  t hat   mul ti — out put   c i r cui t   det ec tabi l i t y  of   a  s t uc k- at   f aul t   cont ai ns  A,al s o c ont ai ns  at  l eas t  one  ST pat h,   s houl d  be   cons i de r ed  at  t he   cor r es pondi ng  out put .   t hen A i s  cal l ed a s i ngl y— t e st abl e— de pendent{ ST—  

de pende nt 1  pat h[ 1 4   J .We   concl ude  t hat  A  need  not   be  t est ed  s i nc e  i t  wi l l   not  caus e  an  i ncor r ect   ope r—   at i on i n a  ci r cui t  t hat  has  pas s ed t he  t es t s  f or   al l   ST  pat hs.  

21  I f   none  of   t he  t es t abl e  gr oups   of   pat hs  t hat   cont ai n A,i nc l udes  any ST  pat h,t hen  A  i s   cal l e d 

a   mul t i pl y — t e s t a b l e( M  pat h.   Def i ni t i on 3. 3 r u nc F t i ona1 ) .   A p at h  i s  

mul t i pl y— t e s t a b l e( M 

a nd   o nl y   a   t e s t   e xi s t s  

j o  a  s e t  o f  s i mul t ane o us l y如ul t y  p at hs 。no ne  o f  whi ch  i s  S  2 o 1 . 

Fi g. 3.Si ng1 y—t est ab1 e  pat hs  

Theor em  3. 1.A  pa t h — d e l a y   f a ul t下P ( J , P)  佗   a   c i r c u i t   i s   ST  a nd   on l y霹t he   s t uc k — at 一 0( 1 、扣ul t  

  t he   f a nou t   b r a nc h   f  o t he   i n put   o r   t he   i nput   l i ne   Def ini t i on 3. 4( St ruct ur a1 ) .   A pa t h  i s   at t s e l f(  i t   ha s   no   f ano ut )o f  t he   c o r r e s po ndi n g   pa t h   mul t i pl y — t e s t a b l e  M  a nd  o nl y   { o r  a  s e t   i n  t he   un f ol d e d   c i r c ui t   i s   t e s t ab l e .   f  o s i ng l y — u nt e s t a b l e   pat h s   i nc l ud i ng  t he  t a r ge t   MT  i pa t h ,t he r e   e x i s t s   a   pa t t e r n- pa i r(  1 , v 2 )s uc h   t hat :   P加o f .Suppo s e个P  i s   t e s t a bl e .The n   b y  de t— f  

( i )t r a ns i t i o ns  wi t h  a ppr o pr i a t e  d i r e c t i on s  a r e  a p一   ni t i o n,t he r e   e xi s t s   a   v e c t o r   pa i r( o1 , , , 02 )t ha t   a l > 

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pl i es  a  r i s i ng t r ans i t i on at  t he  i nput  of   P and al l   t wo  s i ngl e  s t uc k— at   f aul t s   i s   r emoved,i . e. ,r epl aced  s i de . i nput s  of  t he  pat h are  non- c ont r ol l i ng under   by  cons t ant  l ogi c  1.t he  ot he r  s i ngl e   s tuck— at   f aul t  

v2. Unf ol di ng ke eps  t he t opol ogy of  t he ci r cui t   no l onger   re mai ns   r edundant.   unc hanged,al t hough  dupl i c at i on  of   s ome   port i ons   may  caus e   pos s i bl e   1 ogi ca1   r edundanci es.As   t he   un.   f ol ded  ci r c ui t   U  pr es er ves   t he  f unct i on  of   t he   or i gi .   nal   c i r cui t,under   t he   ve ct or   t , 2,t he   s tuck. at . 0  f aul t  

at   t he   i nput   Mnout   br anc h  of   P  wi l l   be   exc i te d  wi t h 

2   10 

1 ogi c  1   bot h  i n  C  and  U.As   non. cont r ol l i ng  val ue s   appear   at   al 1   s i de. i nput s   of   P.the  r e qui r ed  st uc k- at   f aul t   wi l l   be  t e st abl e   i n U.  

I f个 P i s  unt e st abl e,t hen a vect or  Pai r  t hat   pr oduc es  a  r i s i ng  t r ans i t i on  at   t he  i nput   of   P  f ai l s   t o s tat i cal l y s ens i t i z e  t he  pat h P unde r  t , 2.   I n 

3  

Fi g. 4.M ul t i pl y- t est abl e  pat hs  

ot he r   wor ds,t he  cor r es pondi ng  st uck. at . 0  f aul t  i n  U  wi l l   be  undr i vabl e  r edundant.Thi s   happe ns   be -  

Fi nal l y,i f   t he r e  e xi s t s   a   pat h  whos e   c orr e spond.  

ng s t uc k. at   f aul t  i n t he  unf ol de d  ci r cui t  i s   re dun-   caus e  t he   st uck. at   f aul t   of   our   i nt er es t   i s   obs e r vabl e   i da n t   a n d   i f   t h a t   f a u l t   d o e s   n o t   o f r m  a   t e s t a b l e   onl y  al ong  pat h  P  and  not   t hr ough  any  ot he r   pat h.   t i . . f aul t   wi t h  any ot he r  unt es t abl e   s i ngl e  s t uc k. .   Thus   i n  Fi g. 1,t hough  C  was   s t uc k. at   f aul t   i r r edun.   mul a t  f a u l t   o n  s o me  i n p u t   l i n e ,t h e n   i t  i s   a n  S T.   dant,U  has  t wo r edundant  s t uc k. at  f aul ts  a s  t he   nt   pat h.Thes e  ar e   t he   f al s e   pat hs   accor d.   obs e rvabi l i t y of   the  f aul t s   bec omes  more   r es t r i ct e d  depende i n g   t o   Gh a r a y b e h   e t   0 Z . ’ s   c l s a s i i f c a t i o n [ 1 4 j i n  .The  proof   f or   J ,P  ol f l ows   ea si l y.   口  . 

Next ,we   de ri ve   a  s i mi l ar   r es ul t   or f   M T  pat hs.  

Robust  Te s t ab i l i t y. W e  now char act er i z e t he  

Theor em  3. 2.A  s e t   o fl o gi c a l pa t hs   S  i n  a   c i r -   n C.A r obus t  te s t   c ui t   i s   MT对a nd   on l y讨i n   t he   un f ol d e d   c i r c ui t   U  a path to have a robust test i condi t i ons   on  st uck. at  f aul t s   i n  U t hat   wi l l   ens ure  

d  t he  mul t i pl e  s t uc k — a t   f au l t( c o ns t i t u t i n g  t he  s i n g l e   for a path.delay fault is a test which remains vali ong  ot he r   s t uc k — a t   f a ul t s  c o r r e s po ndi n g   t o   t he   pa t hs   i n  S)i s   even in the presence of delay faults al hs. I t  i s  a  non. r obus t  t e st  wi t h a n addi t i onal   t e s t ab l e.Ea c h   o f   t he s e   s i n gl e  s t uc k . a t   f a ul t s   mus t   pat b e  i ndi vi dual l y  r edundant .   ’ D 

condi t i on:i f   i n  t he  s econd  vect or   a n  on. pat h  i nput  

o s ome  gat e  t akes  the  cont r ol hng val ue,t hen al l   Let  t he s et  of  pat hs  S be  M T.Henc e  t

de- i nput s   t o  t hat   gat e   mus t   be   s t abl e  at   t he   non.   eac h pat h i n S i s  s i ngl y unt e st abl e  by de ini f t i on.   si By  Theor em  3. 1.e ac h  of   t he   cor re s pondi ng  s t uck. at   cont r ol l i ng  val ue   or f   bot h  vec t or s .For   a  non. r obus t   f aul t s   i n  U  i s   r edundant .Now,t her e   exi s t s   a  vect or   t es t,i t   i s   e nough  t o  have   t he   non. cont rol l i ng  val ue 

pa i r( Vl , v2 )t ha t   a ppl i e s   a ppr o pr i at e   t r an s i t i o ns   a t  

at   s i de- i nput s   onl y  i n  t he   se cond vec t or .A r obus t  

es t  i s  al s o a non— r obust  t es t,but  t he  conver s e  i s   pat h  i nputs   and  s e ts   al l   s i de - i nput s   t o  t he   paths   S  t t o  non- cont r ol l i ng  val ue s   under   t , 2.The   above   f act   not   t r ue.Hence,r obus t   t e st s   ar e  e s se nti al l y  s i ngl e .   wi l l   e nsur e  t hat   t he   mul t i . f aul t   i s   bot h  exci t ed  and 

i nput — c ha ng e( SI C)t e s t s   s f a or  t e s t i ng  S T pa t hs  

robust  SI C t es t s   ar e  e nough[ 1 4, 2 o 1 s ens i t i z ed by  t he   vect or   v2,i . e. ,t he  mul t i pl e  f aul t   non. . 

wi l l   be  t es tabl e.   The  conver s e  ol f l ows  f r om t he  f ac t  t hat  i f   t he  

I n  t he   ci r cui t   of   Fi g. 1,t he   pat h 个1. 4. 6. 7  ha s  a 

r o bus t   t e s t( 0 0, 1 0) .The   s t e a dy   0   v a l ue   a t   pr i ma r y  

cor r es pondi ng  mul t i pl e  f aul t   i n  t he   unf ol ded  ci r cui t   i nput  2 s et s  al l   s i de- i nput s  of   t he  pa th t o st eady  i s  unt es t abl e  t hen  we   cannot   ind a f   sui t abl e  ve ct or   non- cont r ol l i ng  val ues .However ,t he  pat h个 1. 3. 4 _   v2  t hat   wi l l   make   t he   s et   of   pat hs  MT.  

口  6— 7  ha s  no r obus t  t es t. I t  ha s onl y a non- robust   I n  Fi g. 4,t he   ci r cui t  s hown  i s   al re ady unf ol ded  t e s t( 01 , 1 1 )a s  s ho wn  i n   Fi g . 5( a) .Whe ne ve r   t hi s  

as   t he   f anout s   are   pr es ent   onl y  at   t he  pr i mar y  i n-   pat h  i s   t o  be   s e ns i t i zed  by  a  ri si ng  t ra nsi t i on a  ri s.   put s. Bot h pat hs ,   2. 6 . 9.1 0 a nd  3. 6. 9. 1 0,ar e   i ng t rans i t i on  wi l l  al s o oc cur  at  t he  s i de . i nput  of   ,

non- ST.Ho wever ,t hey f or m an M T  s et  of   pat hs,   gate 4.But  t he  on- pat h  i nput  t o  gat e  4  wi l l   make 

t e s t a bl e   by   t he   v e c t o r   pa i r( 1   1   1 , 1 00 ) .As   p r e di c t e d   a f al l i ng  t rans i t i on,i . e. ,t o war ds   cont r ol l i ng  val ue,   by  Theor em  3. 2,t he  t wo  st uc k. at .1   f aul t s   s hown  i n  whi c h  wi l 1   demand  a   s t eady 1  at   t he   s i de . i nput   or f   t he  igure f   ar e  i ndi vi dual l y  r edundant   but   t he  mul t i .   a  r obust   t es t.So  t he   l at t er   pat h  cannot   have  a  r o-   pl e  s tuck— at   f aul t   cons t i t ut i ng  t hes e  s i ngl e  st uck. at   bus t   t es t.Now  cons i der   t he   cor r es pondi ng  s t uc k. at  

f a ul t s   i s  t e s t a bl e   wi t h  t he   s e c on d  v e c t o r( 1 00 )o f   faul t s   i n  U.Bot h  s t uc k. at   f aul t s   s hown  i n  Fi g. 5  ar e   t he  above  ve ct or  pai r. Thi s  means  i f   any of  t he   te s tabl e   s  a pr edi c t ed by  The ore m  3. 1.The  t es t   or f  

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Subhas hi s   Maj umde r   e t   a1 . :A  Ne w  Cl as s i icat f i on  o f   Pat h— De l a y  Faul t   Te s t abi l i t y 

959 

l l  not  be  s ens i t i zed by t hi s  vect or  pai r . Thi s   t he s t uc k— at 一 0 f aul t  on l i ne  1 - 3 i s( 11) :t hi s  f aul t   G wi l l  ensur e t hat  i f  we t es t  t he  st uc k— at  f aul t  cor —   i s  t he  c or r es pondi ng s t uc k— at  f aul t  f or  t he  pat h 1 、   wi l一 3— 4— 6— 7.Thi s   was   i n  f ac t   t he   se cond  ve ct or   of   t he  r es pondi ng  t o t he   path  1 、P  by t he   ve ct or  v2,any  non— r obust  t e st   or f   t hat   pat h.But  t he   t es t  of   t hi s   s tuc k— at  f aul t   on  t he  i nput   br anch  of   path  P can-   s t uc k— at  f aul t  wi l l  be  i nval i dat ed i f   t he  s t uck— at 一 0   not   i nval i dat e   t he   above   t es t.   f aul t  on l i ne  1- 4 i s  pr es ent . Thi s  i s  not  a  st r ange 

21  The   on— pat h  i nput   t o  some   qat e   G t akes   non  一 c oi nci dence.The   path  1 、1- 4. 6— 7,whos e   cor r es pond.   cont r ol l i ng  val ue   under   v2:By  de ini f t i on,t he   s i de -   .

i ng s t uc k— at  f aul t   caus es   i nval i dat i on of   t he  above  i nput s   mus t   as s ume   non- cont r ol l i ng  val ue   under   v2.   s t uc k— at  f aul t  t e st ,i s  ac t ual l y re s pons i bl e  f or  t he  On  appl yi ng  Vl,i f   t he y  t ake  non- cont r ol l i ng  val ues ,  

non- exi st e nc e   of   t he   r obust   t es t  f or   the  pat h个l一 3—   we   ha ve  not hi ng  t o  pr ove.However.i f   any  of   them  4. 6. 7.A  de l ay  f aul t   on  t he   or f mer   pat h  may  i nval —   t ake s   t he   cont r ol l i ng  val ue,t he   pr oof   f ol l ows   eas i l y.   i dat e  a   non— r obus t   t es t  f or   t he   l at te r   pat h.Thi s   i s   I f   we  t es t   the  s t uc k— at   f aul t   of   our   i nt e r es t   by  us i ng  

s hown i n Fi g. 5f c) .A  l at e  r i s i ng  t rans i t i on  on t he   the vector v2,the  good  val ue   at   t he   on- pat h  i nput   s i de — i nput  of  gate  4 f   due  t o a del ay f aul t  on t he  to gate G  wi l l   be   non- cont r ol l i ng  and  obvi ous l y  t he   or f mer  pat h)wi l l  ens ur e  t hat  t he  out put  of  gat e  bad val ue   wi l l   be   cont r ol l i ng.A  s i de. pat h  P end—  

4  i s  s t e a dy  1  f i ns t e a d  o f   pr od uc i ng   t he  0  p ul s e ) .  

i ng  at   a  s i de — i nput   of   t hat   gat e   G,wi l l   al s o  s sume a   But   the  cor r ect   out put   val ue   or f   gat e   4   i n  t he   del ay  non— cont rol l i ng  val ue   at   t he  s i de— i nput   unde r   v,i f   f aul t   te s t   of   pat h  1 、l 一 3— 4— 6— 7   i s   al s o  1   and  hence   t he   the  ci r cui t  i s  good.But  i f  t he  s tuck. at  f aul t  cor —   ci rcui t   wi l l   be  wr ongl y  i nte r pr et ed  t o  be  c orr e ct.  

r es pondi ng t o pa th P i s  pr e se nt  i n t he  unf ol ded  ci r cui t ,t he   s i de — i nput   t o  gat e   G  wi l l   s sume a   a  c on-  

t roUi ng  val ue( act ual l y  i t   wi l l   l at c h  on  t o  t he   val ue,   t hat   i t   t akes   unde r   v】 ).Henc e,t he   pr e s ence   of   t hi s   unwant ed s t uc k.a t  f aul t  cor r es pondi ng  t o pat h P  wi l l  f lag an  er r or  as   i t  wi l l   f or ce  t he  bad val ue t o   pa ss  t hrough t he  gat e  G. Thus  t he  or i gi nal  t es t  

( a)  

( b)   ●_ —



 

wi l l   no t   be   i nv a l i da t e d   f a t   l e st a   a   ba d   c i r c ui t   wi l l  

no t   be   wr on gl y   la f g g e d   a s   g ood) .   I t  i s  enough t o cons i der  t he  s t uc k. at  f aul t s   pr es ent  onl y on t he  ot her  f a nout  br anches  of   t he   pri mar y i nput  of   P. The re  al wa ys  e xi s t s  an SIC  t es t   i f   a  pat h  i s   r obus t l y  t es tabl e.Hence.we  ne ed  not   cons i der   i nval i dat i ons   caus ed  by  st uc k. at   f aul t s  

( c)   Fi g. 5 .( a)Or i g i na l   c i r cu i t .( b)Unf o l de d   c i r cu i t .( c )Li mi —   t ati ons  of   a  non—r obust  t es t.  

pr es ent   at   ot her  i nput s   of   t he   unf ol ded  ci rc ui t.   To pr ove t he  c onver s e,we  s how t hat  i f   t her e   doe snot   e is x t   a  robus tt e s tf or   al ogi calpat hP,any  t es t  der i ved  t o  t es t   i t s   c or r e spondi ng   s t uck. at   f aul t  

Theor em 3. 3. A pa t h — d e l a y   f a Ⅱ髓1 、P( J ,P)  

can be i nval idate d by t he  pr es ence  of   s ome  ot he r  

i n a  ci rc ui t  i s   robust l y  t e st abl e  ,and onl y  ,t her e   stuck—at  f aul t  i n  t he  unf ol de d c i r cui t.I f   t he  pat h  exi st s a t est厂 0 r   i t s   c o r r e s po nd i ng   s t uc k — a t 一 0( s t u c k —   i s   non— r obus tl y unt es t abl e.t hen  t he  c or re s pondi ng  .

n t — 1).  ul t   i n  t h e   un f o l d e d   c i r c ui t ,whi c h   c a nno t   b e   stuck—at  f aul t  i s  unt es ta bl e. Howe ver.i f   a  r obus t   i n va l i d at e d   b y   t he   pr e s e nc e   o f   a ny   s t uc k — a t   f a u l t   i n   test does not ex ist  but  a non- r obus t  t e st  e is x t s,   a ny   o f   t he   ot he r   f a no ut   b r anc h e s   o 1   t h e   s a me   i n put .   then there mus t  be  a  l ogi c al   pat h P i n  t he   or i gi —  

Pm  Le t( Vl , v2 )be   a   pa i r   of   v e c t or s ,whi c h 

nal   ci r cui t   s tar t i ng  at   t he  s ame   i nput   whi c h,when 

cons t i t ut es  a  robus t  t e st   or f   1 、P.We  c ons i der  t wo  l at e,can  i nval i dat e   t he   non— r obus t   t es t   or f   P.Thi s   CaSeS 

pa t h  P c a n not   j o i n  P a t  a   ga t e   whe r e   t he  pa t h  

l1  The   on— pat h  i nput   t o   s ome   gat e   G on  t he   pat h  P make s  a t r ans i t i on t owards  t he  non- c ont r ol l i ng  t akes  c ont r ol l i ng val ue  under   v2:By def ini t i on  of   val ue   under   the   t es t   vect or   pai r.I n  t hat   cas e,bot h  r obus t  t es t,t he  s i de— i nputs  t o G wi l l   be  st abl e  at   pat hs   wi l l   be  ma ki ng t rans i t i ons  t owar ds  t he   non—   non— cont r ol l i ng  val ue   on  appl i cat i on  of   bot h  ve ct ors   c ont rol l i ng val ue  and  t he   s l ower   pat h  wi l l   act ual l y  V  l  and  v2.So  i r re s pe ct i ve  of   t he  l ogi c  at   t he   i nput   caus e   t he   out put   t rans i t i on  gi vi ng  no  chanc e  of   i n—   of   t hi s   pat h,t he  s i de— i nput s  ar e   s t abl e.He nce  any  val i dat i ng t he  non— r obust  del a y f aul t  t es t. But  i f   s i de   pat h  P ori gi nat i ng  f rom  t he   s ame   pr i mar y  i n-  

i t   j o i ns   P  a t   a   ga t e   G wh e r e   P  i s   ma ki ng   a   t r a n-  

put   as   pat h  P  and  t er mi nat i ng   at   any  s i de - i nput   of   s i t i on  t owar ds   t he   cont r ol l i ng  val ue,t hen  t he   pat h 

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P  .when 1 at e,ca l l  hol d t he  cont r ol l i ng va l ue  t i l 1  

t ha t   t e s t s   t h e   mul t i - f a ul t{1 — 4:s — a . 1 ,1 — 3 ;s — a . 1}i s  

c h  i s  al s o  the onl y vec t or   t ha t  det e ct s  t he   t he  t i me P make s  a  tr ans i t i on  thus  re movi ng t he   00,whi t ect abl e  c omponent   1 - 4:s - a- 1   of   t hi s   mul ti - f aul t.   pul s e f r om  the  output  of   gat e G  .I n t hi s   way,i t   de Th e   o c c u r r e n c e   o f   t h e   r e d u n d a n t   c o mp o n e n t   1 - 3 :s —   can i nval i da te  t he  del ay f aul t   t es t.I f   we  c ons i der     can  never   be  s ce a rt ai ned  by  any  t es t   vec t or   even  t he  vect or  v2  to be  t he  t es t  vec t or  f or   the  cor r e —   a-1 i n   t h e   p r e s e n c e   o f   o t h e r   f a u l t s .Ho we v e r ,i n   F i g. 6,   s pondi ng  s tuck— at   f aul t   of   P,t he n  t hi s   t es t   can be   e exi s t s  a  ve ct or  00 whi ch det ec ts  t he mul t i -   i nval i dat ed  i n  t he   s ame   manner   by  the  pr es enc e  of   ther t he  cor re s pondi ng   st uc k—a t   f aul t   of   P  .  

口 

Cheng and Chen' s  Cl as s  c at i on[ 1 9] . 

f a u1 t{ 1 — 4:s — a . 1,1 — 3:s - a - l }.I nt e r e s t i ng l y ,0 0   do e s  

  t es t   the  det ec tabl e  component  1 - 4:s —a. 1  i n  the  I n thi s   not

enc e  of   the  r edundant   f aul t  1- 3:s - a- l;t he   si n-   c l ass i ic f ati on the r e ar e  t wo cl as s es  of  pat h- del ay  abs gl e  f aul t  1 - 4:s - a一1  i s  de t ect ed onl y by  01.Thus,  

f a ul t s :f unc t i o na l l y s e ns i t i z a bl e( FS)a nd  r e du n-  

he   t e s t   00  de t ect s   t he   r edundant   c omponent   of   t he  dant. The  cl ss a  FS proper l y i ncl udes  t he  non-   t ti - f aul t,whi c h  become s   te s tabl e   i n  t he   pr es enc e  r obus t  cl as s. The  non— robus t  c l ss a  i s  exac t l y the  mul   i t s  det ec tabl e component. So we  obse r ve  t hat   s ame  s  a t he   ST  cl as s   a nd  s o  no  f ur t her   c ha rac t er i za-   of he s e t  of  EFS paths  i s  a s uper s et  of   M T pat hs,   t i on  i s  r e qui r ed.I ns t ead we   def ine  a  new  cl ss a   Ex-   t

c l us i v e  Func t i o na  S e ns i t i z a bl e( EFS 、= FS\ST,  

and henc e.we can wr i te  EFS = M T U  X . The  

ol l owi ng  t heor em  gi ves   a  char act er i zat i on  f or   EFS  cl as s   f ths   i n  t e r ms   of   s t uck— at  f aul t s.   proper l y  i nc l udes   M T  cl ss a   and  c ont ai ns   s ome   mor e   pa whe re \s t ands  f or  s et  di fer enc e. TI 1 e  

The or em  3. 4.A  p n   P 诂  EF| s   t 厂and   onl y   i ff 1 1  t h e   c or r e s po nd i n g   s t uc k — aty a ul t   o l   i n  U  i s   r e —   beh et  a1 . 【 l 4 J .but  f unc t i onal l y s ens i t i zabl e  accor d—   d u nd a nt( h e r e   we   f e a v e   a s i d e   t h e   STp at h s ) ,and( 2)   i ng t o  Cheng a n d Chen[ 1 9 J . The  c ondi ti ons  f or  a   The r e   e x i s t s   a   s t u c k — a t   f a ul t   ( s i ng l e   o r   mul t i pl e )     U and  a  ve ct or   V .s uch  t hat   V de t e ct s   o lU  b ut   f unc t i o na l l y   s e ns i t i z a bl e( FS)pa t h   a r e   s  a ol f l o ws .   打l pat hs   t hat   ar e  f al s e  pat hs.I n  Fi g. 6  we  s t udy  such  a   pat h,whi c h  i s   ST- depende nt   ac cor di ng  t o  Ghara y—  



 not  det ect   al one .   1、I f   t he  pat h i s  maki ng  a t r ans i t i on t owar ds   does non- c ont r ol l i ng va l ue  at  any gat e  i nput ,then  t he  

I f   c onsi s t s  of   onl y  r edundant   f aul t,P ∈ M T,  

si de— i nput s   s houl d a ss ume   non- cont r ol l i ng  val ue   i n  ot her wi s e   P  i s  i n  cl ss a  X .   Pr 00   Le t   Z  s t and  o r“Pat f h  P  i s   i n  EFS”.Let   t h e   s e c o nd  v e c t or( s a me   s  a no n- r obus t   c o ndi t i o n) .   or“   a  s t uc k— at — f aul t   f   s i ngl e  or  mul t i -   2)I f   t h e  pa t h  i s  mak i ng   a   t r a ns i t i on   t o wa r ds   Y stand f cont r ol l i ng  val ue,i t   does   not   mat t er   what   happens  

pl e )i n  U  a nd   a   ve c t o r   V, s uc h  t ha t   V  de t e c t s  u 

  does  not   det ec t   al one ”.   at  t he s i de— i nput s;her e  t he  t es t abi l i t y c ondi t i on  but ge ts   r el axed.  

W_ e  ha ve  to  pr ove   that  Z 

y.Now Y 

Z 

s   equi val ent  t o  Z =}Y .W l e   us e  t he   above   equi va-   Cl ear l y,the above  defni t i on i nc l ude s  t he  ST  i l ence   i n  t he   c onver s e  pr oof .Let   P  be  a  path  tha t   i s  

pat hs.  

not   i n  FS. i . e. .i t   i s   i n  the   r edundant   c l ss a   acc or di ng  t o Che ng and Che n’ s  c l ss a [ ica t ti on.Ⅵ  now  con-  

s —a  1] 

s i de r   the  8  pos s i bl e  c ombi nat i ons   dependi ng upon  t he  di r ect i on  of   s i gna1   t rans i ti on  or f   bot h  on— pat h  and oi f- pat h i nput s .   For  s i mpl i c i t y and wi t hout   l os s  of  generahz at i on we cons i de r  onl y t wo- i nput   Fi g. 6.Funct i onal l y  sens i t i z ed ST- dependent  path 

The  path J ,1- 3 — 4— 5 i s  i n 

g a t e s .An  n— i nput   AND( OR,xOR)g a t e   ma y  be   conve r te d  i nt o  a  chai n  of   n— —1   2- i nput   gate s   of   the  

a me   t y pe   and   a n   n— i nput   NAND ( NOR,XNOR)   s i a t  f ol l o ws  t he   s

above  def ini t i on.   But  i t  i s  ST— de pe ndent  on the 

ga t e   i s   e qu i v a l e nt   t o   a   c ha i n  o f   n一1   AND ( OR,  

 gat e s  wi th t he   l as t  one  ha vi ng  a bubbl e  at   ST  pat h上1 - 4— 5,becaus e   a  f al l i ng  t r ans i t i on  at   the  XOR1 pat h  i nput   al ways   br i ngs   a  c ont r ol l i ng  val ue   t o  the 

i t s   o u t put( s e e   Fi g . 7   f or   e xa mpl e ) .Thi s   c o nv e r s i o n 

  not   al t er   t he   topol ogy  of   t he   on- pat hs   and  oi f-   si de— i nput   of   gat e   4.Not e  that   t he  si ngl e  s t uc k—a t 一   does   or f mal   pr oof   i s   i nt ui t i vel y  obvi ous  a n d  1   f aul ts   on  f anout   br anches  1 - 3  and 1 - 4  ar e   r edun—   paths.The e  we   omi t   i t  her e.   da nt   and  t es t abl e,r es pect i vel y,i n  acc or danc e  wi t h  henc

Theor em 3. 1.However ,t he  ST— depe ndent  pat h上 

We  now expl ai n how t he  above  conf igur at i ons  

n Tabl e 1  afec t  te s tabi l i t y of  a pat h. W e con-   1 — 3— 4— 6— 7  i n Fi g. 3  i s  not  i n FS al t hough t he  s i n-   i i der  t he c ondi t i on of   ever y gat e  on t he  pat h un-   gl e  s t uc k. . at . . 1  f aul t s  at  1- 3 and 1- 4  ar e  r edundant   s  al l  i nput  vect or  c ombi nat i ons. I f   or f  a  pat h  and t e s tabl e,re s pe ct i vel y. So what  di s ti ngui s hes   der be t ween  t hes e   t wo  ca s es 7 .  I n  Fi g. 3,t he   onl y  ve ct or   Pl  t her e  e xi s t s  a  vect or   pai r  f or  whi ch  ever y gat e  

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Subha shi s   Maju mde r   et   a1 .  A  New  Cl a s s i icat f i on  o f  Pat h— De l a y  Faul t   Te st abi l i t y  t  ca s e,we  c an  obs e rve  a  pul s e,but  t he  s e cond  on  t hat  pat h  has   one  of   t he   conf igur ati ons  1,4,5、   bes of   t he   pul s e   wi l l   be   det er mi ned  by  t he   of . path  and  8,t he n  Pl  bel ongs   t o  t he   c l ass   of   non- r obust l y  edge  t es t abl e  pat hs . Thi s  f ol l ows  eas i l y f r om t he  def i I   i nput   as   i t   i s   goi ng  t owar ds   cont r ol l i ng   val ue.I n  t he   ni t i on  of   non— r obus t l y t e st abl e   pat hs .Suppos e  f or   corresponding U we wi l l   have   c ompl eme nt ar y  er r or   pat h  P2   such  a  vect or   doe s   not   e xi s t,t hen  i t  i s   not   non— r obus t l y  t es t abl e  but   mav  be   i n 

v al u e s( D, D)f e e di ng  t hat   ga t e  whi c h  wi l l   ma ke  

or   ma y  be   i t   i mposs i bl e   t o  t es t   t he  f aul t  e ve n  wi t h  any  ot he r  

r edundant.So  or f   P2,under  ever y  poss i bl e   ve ct or   c ombi nat i on  of   f aul t s.   pai r,i n  s ome  gat e  on  P2,one   of   t he   c onf igur at i ons  

To  s how  t hat   Z = Y  we   cons i der   Tabl e   1   agai n.  

2.3,6.or  7  oc cur s. I f  t he r e e xi s t s  a vec t or  pai r   We have  t o prove  t hat  i f   or f  a vect or   t , .t he  gat e   or f  whi c h t hat  occ ur r ence  i s  l i mi t ed t o conf igur a—   c onf i gurat i ons   ar e  l i mi t ed t o  Cas es  1,4,5,6,7,or   t i on 6 and 7  onl y.t hen  P2  bel ongs  t o  .But  i f   8  t hen  Y  hol ds.Ca se s  1,4,5,and  8  f aI I   unde r   ST  or f  a  pat h,unde r  e ve r y  ve ct or  pal r,at  some   gat e   f non— r obus t l y t e st abl e)c at e gor y,and he nce  ne ed  on i t,ei t her   Cas e  2  or   3  occ ur s,i t  bel ongs  t o t he  not   be   cons i de re d.Thus,we   nee d t o   show  that   or f   r e dundant  c l as s. Al l  t he s e  as s e rt i ons  di re ct l y f ol —   Cases  6   or  7,pr opos i t i on  Y  hol ds.   l ow  f r om t he  de tni f t i ons  of   di ier f ent  c l as s i icat f i ons  

Fi r s t,l et   us   c onsi der   t hat   or f   a  pat h  P  and  or f   of  Cheng and Che n.Next,we  s how t hat   i f   e i ther   ever y  pos s i bl e   i nput   vect or,at   l ea st   one   gate   G  s— a   2   or   3   i s   t r ue   at   any  gat e   or f   any  pat h  P,t he n  t he  s ume s  t he  c onf igurat i on 7. Furt he r,t he r e exi s ts   pr oposi t i on  Y  does   not   hol d.  

one  vec tor  f or   whi c h ot he r   gat es   ha ve  t he   conf igu-   r at i ons  1,4,5,or   8,i . e. ,6  doe s   not   occ ur.Thus   at  

Tabl e 1.Pos si bl e  Tr ans i t i ons  

t he   gat e   G,bot h  t he  on— pat h  and  oi f- pat h  t ake   c on-   t r ol l i ng  val ue  under   t he  s ec ond vec t or 。I f   we   now  c ons i der  t he  t wo cor r es pondi ng st uc k— at  f aul t s  i n  U  or f   t he   on— pat h  and t he  of . pat h  at   gat e   G,then  t he   c ombi nat i on  of   thes e   t wo   f aul t s   wi l l   be   t es t abl e.   I f   G  i s  t he   onl y  gat e   wi t h  con i gu f r at i on  7.t he n  al l   ot he r   gat es  wi l l   ha ve   non- c ont r ol l i ng  val ues   at   oi f-  

p at h   i nput s( 1 ,4,5,o r   8)i n   t he   pr e s e nc e   o f   t he   s e cond vec tor .He nce,t he  c ombi nat i on  mul t i - f aul t   c an  be   pr opagat ed  t o   s ome   out put.W e   t hus   have   a  

re pr es entat i ve  f aul t   ,whi c h i s  t he  c or re s pondi ng  st uc k— at  f aul t  of  t he of . pat t h i nput . The  f aul t   .   howe ve r,cannot  be  t es t ed al one  as  t he  c once rned 

3  4 

on— pat h  wi l l   ac t   s  a of- pat h  at   gat e  G,and hol d  i t   8  

t o  t he  cont r ol l i ng  val ue.W e   s how  t hi s   on  a  t ypi cal   e xampl e   use d  by  Che ng  et   a1 . 【  引.I n  Fi g. 8  t he   pat h 

J ,a- x— Y— z — w  i s   f unct i onal l y  se ns i t i zabl e   and  t he   gat e   wi t h  out put   z  be l ongs   t o  con i gur f at i on  7.I t   i s   ea s y 

t o  obs e r ve  t hat   i s  t he  s - a-1  f aul t  at  t he  f anout   3  4 

branc h of   a,and  i s  t he  s - a一 0 f aul t  at  t he   f anout   8 

Fi g. 7.Typi cal   ci r cui t  and i ts   t wo-i nput   equi val ent  

branc h of   c.The   mul t i — f aul t  f a,   )wi l l  be  t es t ed 

by   t he   ve c t o r( 0 , 1 , 1 )f or   i n put s   a,b ,a nd   c .Thi s   vec t or  cannot   t es t   al one  s  a Y  wi l l   be  s et   t o  l ogi c  

  i n  t he   abs enc e  of   t he   s t uc k— at   f aul t   .   Let  t he  unt es t abi l i t y of   pat h P be  due  t o oc—   0 cur r enc e  of  Ca se  2. The n f or  ever y vect or  V ,at  

I n  a  gene r al   ca se  havi ng  mor e   gat es   on  path  P 

t h  con i gu f r at i on 7,we   cons t ruct  t he  mul t i — f aul t   s ome   gat e  i nput,t he  s i de— i nput  r emai ns  at  s t eady  wi cons i de ri ng  t he   cor r es pondi ng   st uck— at   f aul t s   i n  cont r ol l i ng  val ue   or   some   gat e   wi l l   r ec ei ve  c ompl e—   by 

or f   t he   on- pat h  and  al l   t he   of- pat hs   t hat   end  at   mentar y e rr or  val ue s( D, D1  at  i t s  t wo  i nput s .I t   U  t h  c onf igu r at i on  7.   i mme di at e l y  ol f l o ws  t hat  t he  s t uc k— at  f aul t  at  t he   the gates wi i nput   of   t he   on- pat h  P  can  ne ve r   be   t e st e d;i n  ot he r   Fi nal l y  we   c ons i der   Ca se   6.W e   ss a ume   that   or f   wor ds  a   re pr es ent at i ve   c annot   be  f ound.   e ve r y  vect or   pai r   s omewher e   t he   gat e   conf igur at i on  I n  Cas e  3.t he   on— pat h and  of- pat h  s i gnal s   wi l l   occ ur s   s  a i n  Cas e  6.Fi r s t   l et   us  a sS Ul TI e   t hat   t he re  

be   goi ng  t owar ds   oppos i t e   di r ect i ons.Hence,a   de f -   i s  one  s uc h vect or   V  or f   whi c h c on i gu f r at i on  6   oc—   i ni t e   t r ans i t i on  at   t he   out put   i s   not   pos s i bl e.I n  t he   c rs u  at  onl y one  gat e. Let  t he  s t eadY cont r ol l i ng 

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J.Comput.Sci .& Techno1 . ,Nov.2004,Vo1 . 19,No・ 6 

962 

i n  t h e   un f o l de d   c i r c ui t   t he   mul t i pl e   s t uc k — a t   i a u如M  c o ns t i t u t i ng   t h e   s i n gl e   s t uc k — a t   f a ul t s   c or r e s po nd i ng   t o   t h e   p a t h s   n   S   s   t e s t a b l e .A n y   p r o p e r   s u b s e t   o f   i nput  f s ee  Fi g. 91.The   s econd vect or   of   V  wi l l   be   vcl ue  at   the  of- pat h i nput  be 0.The n  the  r epr e —  

s e   nt at i ve  f aul t   i s  t he  s - a- 1  f aul t  at  the  of- pat h 

t h e   r e qui r e d  t e s t   f o r   t he   mu l t i — f au l t( o L ,  ) .No t e  

M  i s  r edundant .  

Pr oo f.Same as  Theor em 3. 2  wi th mi ni mal i t y 

t hat   i t s el f   i s   unexci t abl e.As   i n  the  s e cond  vec tor ,  

i der at i on  on  t he   s et   of   f aul t s.   t he  on— pat h goes  t owa rds  t he  c ont rol l i ng  val ue,i t   cons

口 

cannot  det ect   a l one.I f   c onf igurat i on  6   oc cur s   at  

La m e t   a 1 .pr o v e d   a   t he o r e m( Th e o r e m  4 . 2   )  

mul t i pl e  pl ace s,t he   mul t i — f aul t   may  be  cons t r uct e d 

c o nc e r ni ng   r o bus t   de pe nd e nt( RD)pa t hs ,whi c h   i s  

by  t aki ng  al l   s teady  c ont r ol l i ng   val ues.  

e xact l y c ompl ement ar y  t o  the  above  t heor em.By  口 

t hat  t heor em.a  s et  of   pat hs   bel ongs   t o  t he   RD  s et   i f   and  onl y i f   t he   mul t i pl e  s t uc k— at   f a   ul t  at  t he  i n—   put   l i ne s   of   t he   c or r es pondi ng  pat hs   i n  t he   l eaf - dag  i s  r e dundant.A nat ur al  c oncl us i on  f r om  thi s  ob—   s er vati on  i s   t hat   t he   t wo  s et s,pr i mi t i ve — depe ndent   and RD,a re  s ame. I n ot he r  wor ds,i n Fi g. 2,t he   l i ne  se par at i ng  t he   s et s   non— RD  and  RD s houl d  be 

s, a. . 1  

ver t i cal l y  al i gned  wi t h  t he   one   s epar ati ng  the  pr i m—   i t i ve  MPDF  and  the  pri mi t i ve — de pe ndent  s et .  

Fi g. 8.Typi cal   exam pl e  of   FS pat h 

4  Concl usi on 

We   have   pre s ent ed  a  uni ied  f appr oac h  t o  char ac —   3 

t er i zi ng  di fer ent   cl as s i icat f i ons   of   path— de l a y  f aul t s   i n t er ms  of  s t uc k— at  f aul t s. Var i ous  c l ss a i icat f i on  s c hemes,l i ke  ST,MT,FS,r obus t,RD,pr i mi t i ve  

1  

M PDF,pr i mi t i ve — dependent,have be en pr oper l y 

2 

c harac t er i zed.Fr om  a  t heor et i cal   vi ewpoi nt ,thes e  

c harac t er i zat i ons   m ake   t he   unde r st andi ng   of   path—   Fi g. 9.Exam pl e  f or   Cas e 6.  

del a y  f aul t s   muc h  eas i er   than  bef or e,s i nc e  s t uck— at  

aul t  t es t abi l i t y i s  a we l l - s t udi e d domai n f or  t he   Si u n mm0n  and  St r o j was’ Cl a s s i ic f a t i o n[ 。   】   f es t i ng c ommuni t y. The  c orr e l at i ons  obt ai ned  are   Thi s  has  t hr ee  di fe r ent  cl as s es : pr i mi t i ve.SPDF  t t i g h t   a n d   e s t a b l i s h   t wo — wa y   i mp l i c a t i o n s . He n c e ,   f same as  ST),pr i mi t i ve  MPDF,and pr i mi t i ve—  

l   t ype s   of   pat h— del a y  f aul t s   can  be   r e— c l s si a ied  f us —   dependent . The  pr i mi t i ve M PDF s et  i s  a pr oper   al i n g   s t u c k — a t   f a u l t s   a l o n e .Ap p l i c a t i o n   o f   t h i s   i d e a   s ubs et   of   M T  c l as s ,whi ch  e xc l udes   s ome   of   t he   f al se   pat hs   by  def ini ng  t hi s   s e t   car ef ul l y.  

De ini f ti on  3. 5.A  pa t h — de l a y   f a ul t   F  i s   s a i d   t o   b e   pr i mi t i ve  

t o  re al - l i f e   del ay  t es t i ng  needs   f urt he r   i nves t i gat i on.   Acknowl edgem ent   We  woul d l i ke  t o  t hank  t he   r evi ewer s   or f   pr ovi di ng  cons t r uc t i ve  c omment s  

(11  i t   i s  s ens i t i z abl e   and  

t hat  hel ped us  t o  i mpr ove  t he  pr es e nt ati on of   t he 

( 2)no ne  o f   i t s  pr o pe r  s ub 4a ul t s  i s  s e ns i t i z a—  

paPer 

bl e [ 2   4 I .

 

The   de l a y  f aul t  F  may  c ons t i t ut e   a  s i ngl e   pat h  or   mul t i pl e   pat hs.The   onl y  di fer enc e  bet ween  M T 

Ref erences  

pat h  and  pr i mi t i ve  MPDF  i s   t hat   or f   a  s et   of   pat hs   M  whi c h  i s   M   none   of   the  c onst i tuent   pat hs   i s   ST  but   a   pr oper   s ubs et  P  of   M  ma y  be  as   wel l   s  a M T.  

[ 1 】Kr s t i d   A,Che ng   K  T.Del a y  Fa ul t   Te s t i ng   f o r   VLSI   Ci r -   cul t s.Bost on:Kl uwer   Academi c Publ i shers,1998.  

[ 2 】Li n  C  J,Re ddy  S M.On  de l a y  f a ul t  t e s t i ng  i n  l og i c  

I n  t hat   c s e  a t he   s et   M  may  be  de pendent   on  P  and 

ci r cui t s.IEEE Tr ans.CAD.Sept.1 987、6 694-703.  

need not  be  t es t ed s epar at e l y f or  del ay. The s e t,  

『 3 1  Smi t h   G  L.Mode l   or f   de l a y   f aul t s   ba se d  u po n   pa t hs .I n   Pr o e .I nt e r na t i o na l   Te s t   Co @ ,0c t .1 9 85,PP. 3 42 —3 49.   『 41  Ai t ke n   R  C. Nan ome t e r   t e c hno l og y   e f f e c t s   on   f aul t   mod-  

\pr i mi t i v e — MPDF=p r i mi t i v e — d e pe nde n t \ST-   depende nt,may  be  t er me d  as  M T- de pe ndent.W e  

el s  f or   IC t es ti ng  IEEE 

modi f y Theor em 3. 2  sl i ght l y to  c har act er i z e t he  

48:46—51.  

pr i mi t i ve   M PDF s e t   of   pat hs.  

Theor em 3. 5. A s e t   o f   l o g i c a l   pa t h s  S i n  a   c i r c ui t   f o ms   a   pr imi t i v e   MPDF  s e t玎a nd   o nl y   i f  

ns.Comput ers、Jan.1999 

[ 5】Ne e dh am  W  N,Pr un t y   C,Ye oh   E  H.Hi gh  v ol ume   mi -   cr opr ocess or   tes t   escapes,an  anal ys i s   of   def ect s   our   t es t s  

a r e   mi s s i n g.I n  P7 " o c .I nt e na r t i onal  Te s t  Co@ ,0c t .   1998,PP. 25-34.  

维普资讯 http://www.cqvip.com

Subhas hi s   Maj umde r   et   a1 . :A  Ne w  Cl as s i ic f at i on   of   Pat h— Del a y  Fau l t  Tes t abi l i t y 

[ 6】Kr i s na ma c ha r y  A,Abr aha m J  A.Efe c t s  of   mu l t i c y -   cl e  sensi t i zati on on del ay t est s.In Proc. I nt er nat i onal  

Co 

VLSI  Desi gn,Jan.2003,PP. 137—142.  

『 71  Pomeranz  I,Reddy S  M .On t he  number  of   t est s  t o de -  

963 

Subhashi s   M aj umder   i s   a   prof essor  and cour se l eader f or  

the Computer  Sci ence and En-   gi neeri ng Depar tm ent  of  I nter -  

tect   al l   path del ay  f aul t s   i n  combi nati onal   l ogi c  ci rcui ts.  

nati onal   I nsti tute  of   Inf o rmati on 

IEEE 

Technol ogy,Kol kata.He  s tar ted 

us.Comput ers.Jan.1996.45:50-62.  

[ 8 】He r a gu   K,Pat el   J   H,Agr awal   V  D.Fa s t   i de nt i ic f a t i on  

hi s career  i n Texas  I ns trum ents  

of   unt es t abl e del ay f aul ts  usi ng i mpl i cat i ons. I n Pr oc.  

I ndi a Pvt. Ltd. and has over  

nt I er n at i onaL  Conf .cAD Nov.1997 PP. 642—647.  

seven years  of  i ndustr y experi -  

[ 9 】Spar mann   U,Lu xe nbur ge r   D,Che ng   K  T,Re ddy   S  M.   Fast   i dentmcati on  of   r obus t   dependent   pat h  del ay  f aul ts.  

ence.He  recei ved  hi s   M. Tech  de—   gr ee  i n  computer  s ci ence  f rom  the  I ndi an  Stati s ti cal   I n—  

I n  Pr oc .  30 t h  De s i g n Aut o ma t i on  Co n ] . .J une  1 99 5.   sti tute,Kol kata i n 1996.Hi s undergraduate wor k wa s  PP. 1   19-1 25.  

done  i n the El ectroni cs  and Tel ecommuni cati on Engi —  

yi ng untes tabl e  [ 1 0 】Li a ng   H C,Le e   C  L,Che n  J E.Identif neeri ng  Dept.of   the Jadavpur  Uni versi ty,Kol kata.He  f aul ts  i n s equent i al  ci r cui t s  

I EEE  De s i gn  a nd  Te st   o i   。 al s o wor ked as a r esearch a s si stant  i n the Computer    Co mput e r s ,1 995,1 2( 3) :1 2  23.

[ 1   1 】  F e kuma l l a  R,Me non   P R.I d en t i f yi n g  r e dunda nt   pat h  del ay  f aul t s   i n  sequenti al   ci rcui t s.I n Proc.9t h  nt I er n a—  

t i o na l   Con ] .VLSI   De s i g n,Ja n.1 99 6,PP. 406 — 41 1.  

[ 1 2】Ma j umde r  S,Ag r a wa l   V D,Bu s hne l l  M L.On  de l a y—  

Eng.Dept.of  Rutgers   Uni ver si t y  f or   a  year.He  ha s  l ed  product devel opment teams  worki ng  on protocol   stack  devel opm ent  as wel l  as Vl 0IP.Hi s current  area s  of  i n—   teres t  i ncl ude  del ay f auI t  testi ng,wi re routi ng,parti -  

untes tabl e paths  and s tuc k— f aul t  r edundanc y. I n Proc.  

ti oni ng,appr oxi mati on al gori thms,and appl i cati on of  

16t h  IEEE VLSI T e st  Syr up. ,1998,PP. 194—199.  

computati onal  geometry  to CAD pr obl ems.  

[ 1 3】La n W K,Sa i l da nha  A,Br a yt o n R K,Sang i o v anni —   Vi ncent el l i  A L.Del ay  f aul t  coverage,t est  s et  si ze,and 

perf or m ance   trade— ofs.I EEE Tr ans.CAD,Jan.1995,   1 4:32-44.  

Bhargab B. Bhattacharya r ecei ved the B. Sc.   degree i n physi cs f rom the Presi dency Col l ege,Cal -  

Tech.   and M . Tech. degrees i n radi o-   [ 1 4】Ghar a ybe h  M A,Bus hne l l   M L,Agr a wa l   V D.Cl as s i —   cutta.the B. icati f on and tes t  gener at i on f or  path-del ay f aul ts  usi ng 

physi cs  and el ectr oni cs,and the  Ph. D.degree i n com-  

si ngl e  s tuck— f aul t  tes ts . J.El ect roni c Test i ng: The ory 

puter sci ence  al l  f rom the  Uni versi ty of  Cal cutta,I n—  

and Appl ic at i ons,Aug.1997,11:55—67.  

di a.   Si nce  1982,he ha s  been on the  f acul t y of the  

[ 15 】Ghar a ybe h  M  A,Bus hn el l  M L,Agr a wal  V D.Fal s e —   Indian Statistical Institute,Calcutta,where currently  path r em oval  usi ng del ay  f aul t   si m ul at i on.In Proc.7t h 

IEEE  Asi an T e st  Syr up.  Dec.1998.  

he i s  a f ul l  prof essor. He vi si ted the Depart m ent   of Computer  Sci ence and Engi neeri ng.Uni versi ty of 

[ 1 6】Maj hi   A  K, Ja c ob   J,Pat n ai k  L  M, Ag r a wal   V  D.On   t e s t   Nebra s   Li ncol n,USA,dur i ng 1985—1987,and 2001-  cover age  of   pat h  del ay  f aul t s.I n  Pr oc.9t h  nt I er n at i onal  

Co 

VLSI  Des i gn,Jan.1996,PP. 418—421.  

[ 17 】  Sa l danha  A,Br a yt on  R,Sang i o v anni — Vi nc e n t e l l i  A.   Equi val ence  of   robust   del ay— ・ f aul t  and s i ngl e  s tuck— ・ f aul t  

2002,and the FauI t—Tol erant  Com puti ng Group.I nsti —   tute  of   I nf ormati cs,at  the  Uni ver si t y  of  Potsdam ,Ger—   m any duri ng 1998-2000.Hi s  resear ch i nterest  i ncl udes  

t est  generati on.   In Proc.   29t h Desi gn Aut om at i on 

l ogi c s ynthesi s  and tes ti ng of  VLSI  ci r cui ts,physi cal  

Co  ,June  1992,PP. 173—176.  

desi gn,graph al gor i thms,and i mage process i ng archi —  

[ 18 】Spar ma nn U,Koe l l e r  L.I mpr o vi n g pa t h  de l ay  f aul t  

tecture. He ha s  publ i shed more than 130 papers  i n 

t estabi l i t y by path r em ova1 .I n Proc. 1   6t h  IEEE VLSI 

a r chi val  j our nal s  and r e f e r e e d c onf er e nce   pr oce e di ngs ,  

e st T   Syr up. ,1998,PP. 200—208.  

and  hol ds   6 Uni ted States   patents.Curr entl y,he  i s  col —  

aborati ng wi th I ntel  Cor porati on,USA,and I RISA,   [ 19 】Ch en g   K  T, Che n   H  C.Cl ss a i ic f at i o n  an d  i de nt i ic f a t i on   l of   nonrobus t   unt es t abl e  pat h  del ay  f aul t s.I EEE  Trans.  

France,f or  devel opment  of  i mage processi ng hardware 

CAD,Aug.1996,1 5:845-853.  

and  reconf i gur abl e  paral l el   computi ng  tool s.Dr.Bhat—  

[ 20 】  Ghar a ybe h  M  A.Te s t i ng   or f   t i mi ng   c or r ec t ne s s   of   hi gh —   tacharya i s a f el l ow of  the Indi an Nati onal  Academy  s pe e d   VLSI   c i r cu i t s[ Di s s e r t a t i on ] .ECE  Dept . ,Ru t g e r s   of Engineering. He served on the conference commit—   Uni vers i t y,Oct.1996.   t ee s  of   t he  I nt e r na t i onal  Te s t  Conf e r e nc e( I TC) ,t he   [ 21 】Si v ar a man   M,St r oj wa s  A  J.Pr i mi t i ve   pa t h   de l a y  f aul t   As i a n Tes t  Sympos i um ( ATS) ,t he   VLSI  De s i g n and  i d en t i ic f at i on.I n   Pr o c .1   Ot h   I nt e n at r i o nal   Con ] .VLSI   Desi gn,1997,PP. 95—1 00.  

Te s t   Wor ks ho p  f VDAT) ,t he   I nt e r nat i onal  Conf e r e nce   on Adv anc e d Comput i ng  f ADC0MP) ,and t he   I nt e r —  

[ 2 2】Maj hi   A  K,Agr awal   V  D.Tu t o r i al :De l a y  f au l t   mod el s   nati onal  Conf erence on Hi gh— Perf or m ance Com puti ng  and c overage.I n Pr oc.11t h  Int er n at i onat  Conf   vLsI   ( Hi P C) . F b r   t h e   I n t e r n a t i o n a l   C o n f e r e n c e   o n   VL S I   De —   Desi gn,1998,PP. 364—369.   s i gn,he  s e r ve d a s   Tut or i al  Co -Chai r( 1 994) ,Pr ogr am  [ 2 3】Ch en g  K T,Che n H  C.De l a y  t e s t i ng  f or  non — r obu s t   C o - C h a i r( 1 9 9 7 ) , Ge n e r a l   C o - C h a i r   f 2 0 0 0 ) , a n d   a s  a   unt e s t abl e   c i r c ui t s .I n  Pr o c .I nt e n at r i onal  Te s t   Con ] . ,   0ct.1993.PP. 954—961.  

m ember  of  the Steer i ng Commi ttee  duri ng 200  1—2003.  

s  on the ed ori al  boar d of  the Jour nal  of Ci 卜  [ 2 4】Ke   W,Me no n  P  R. Synt h e s i s   of   de l a y— v er i iabl f e   c ombi —   He i nati onal  ci r cui t s. I EEE Tr ans. Comput ers ,Feb. 1995,   44:21 3-222.  

cu s ,Sys t ems ,and  Comput e r s( wl 0r l d  Sci ent i f i c,Si n-   g a po r e ) ,a nd  t h e   J o ur na l   o f   El e c t r o ni c   I 、 e s t i ng :The o r y   a nd   Appn c a t i o ns( Kl u we r   Ac a de mi c   Pu bl i s h e r s , us A) .  

维普资讯 http://www.cqvip.com

964 

[ h t t p: / / www. i s i c a 1 . a c . i n/  ̄b ha r g a b ]  

J.Comput.Sci.& Techno1. ,Nov.2004,Vo1. 19,No. 6  In 1998.he r ecei ved the Harry H.Goode M emori al  

Award of  the  IEEE Computer  Soci ety f or  i nnovati ve 

Vi shw ani  D . Agrawal  i s the James J.Dana-  

contri buti ons to the f iel d of  el ectroni c tes ting,and i n 

her Pr of essor of  El ectri cal  and Computer Engi neeri ng 

1993,recei ved  the  Di s ti ngui shed  Al umnus  Award  of  the 

at  Auburn Uni ver si t y,Al abama. He has over  thi r ty 

Uni versi ty of  I l l i noi s  at  Urbana-Champai gn,i n recog-  

years  of i ndus try and Uni versi ty experi ence,worki ng 

ni ti on of  hi s  outstandi ng contri buti ons  i n desi gn and 

at   Bel l  Labs.M urr ay  Hi l l ,NJ:Rutger s  Uni ver si t y,New 

test  of  VLSI  systems.Dr. Agrawal  i s  a f el l ow of  the 

Brunswi ck,NJ;TRW ,Redondo Beach,CA:II T,Del hi ,  

IEEE.the ACM ,and I ETE—I ndi a. He ha s  served on 

Indi a; EG&G .Al buquerque.NM ;and ATI.Cham-  

the advi sory boards  of   the  ECE Department s at  Uni —  

pai gn.IL.Hi s  areas  of   work i ncl ude  VLSI  testi ng.1 ow—  

versi t y of  I l l i noi s,New Jer sey Insti tute of   Technol ogy,  

power desi gn,and mi crowave antenna s . He  obtai ned 

and the Ci t y Col l ege of  the  Ci t y Uni versi ty of  New 

hi s  B. E.de gr e e  f r om t he  Uni ver s i t y of   Roor k ee  f r e —   name d  s  a I ndi an  I ns t i t ut e   of   Tec hnol ogy.Roor ke e) ,I Ⅱ_  

5 ( o r k .『 h t t p: / / www. e c e . wi s c . e du /  ̄v a ]  

di a.i n 1964;M . E.degree f rom the Indi an Insti tute of  Sci ence,Bangal ore,I ndi a,i n 1966;and Ph. D.degree 

Mi chael  L.Bushnel l  i s  a prof essor and a Board 

i n el ectri cal  engi neeri ng f rom  the  Uni versi ty of   Il l i noi s.  

of  Trus tees  Research Fel l ow i n the  El ectri cal   and  Com-  

Ur bana-Champai gn.i n 1971. He  has publ i shed over 

puter Engi neeri ng Department at  Rutgers  Uni vers i t y,  

250 papers,ha s  coauthored f ive  books and hol ds  thi r-  

New Jersey. He wa s  al so a Henry Rutgers Research 

teen Uni ted States patents. Hi s textbook,Essenti al s  

Fel l ow.He ha s  24 years  of   industry  and uni versi t y ex—  

of   El ectroni c Testi ng f or  Di gi ta1 .M emory and M i xed.  

peri ence,worki ng at General  El ectri c,Honeywel l ,I n-  

i con,and Rutgers  Uni versi t y. He recei ved  Si gnal  VLSI  Ci rc ui t s  f   Kl uwer  Ac ademi c  Publ i s he r s ).   stron,Appl co-authored wi th M .L.Bushnel l ,wa s  publ i shed i n 

hi s Ph. D.degree i n 1986 and hi s  M . S.degr ee i n 1983,  

rom Carnegi e Mel l on Uni versi t y.Hi s  undergrad—   2000. He  i s  t he  f ounde r  and Edi to r - i n— Chi ef   f   1 9 90一 )   both f of  the Journal  of  El ectroni c Testi ng:Theory and Ap-  

uate  work wa s  done at the M a s sachusett s Insti tute of  

s a Presi denti al  Young Investi gator   pl i ca ti ons ,and   a  pas t   Edi t or - i n- Chi e f   f   1 985—87)of   t he   Technology. He i I EEE Desi gn & I1 es t  of  Computers  m agazi ne. He i s   f   1 990)of   t he   Nat i onal   Sci e nce   Founda ti on  of   t he   Uni t e d  the  Founder and Consul ti ng Edi tor  of  the Fronti ers  

St at e s .He   i s   a   c o- au thor   of   4  book s   f   i nc l udi ng   t he   l e ad—  

i n El ectroni c Testi ng Book Seri es  of   Kl uwer  Academ i c 

i ng VLSI  testi ng textbook enti tl ed Essenti al s  of   El ec—  

Publ i shers.Boston. He i s  a co- f ounder  of  the I nter-  

t roni c Tes ti ng f or Di gi tal,M emory and M i xed-Si gnal  

nati onal   Conf erence on VLSI  Desi gn.and the Interna-  

VLSI   Ci r cui ts( Kl uwe r   Ac ade mi c   Publ i s he r s ,2000) ,c o.  

ti onal  W orkshops  on VLSI  Desi gn and Test.hel d an-  

au thor e d wi t h Vi s hwani  A ̄r a wa1 ) ,91  pa pe r s ,and 7  

nual l y i n Indi a. He  ha s  served on numerous  conf er—  

patents. He i s  t he co-author  of  two Pri ze Papers  and 

ence commi t tees and i s  a f requentl y i nvi ted speaker.  

one  Honor abl e  M enti on  paper.He  served  twi ce  s  Pro- a  

He  wa s  the i nvi ted Pl enary Speaker at the 1998 I nter-  

gram  Co-Chai r   of   the  I nternati onal   Conf erence  on  VLSI  

s i gn( 1 995  and 1 996) ,and  t wi c e   s  a t he  Conf e r enc e   st Conf erence.W a s hi ngton D. C. .and the  De ce—Chai r  of   the  North Atl anti c  Te stⅥ, orkshop f 2002  Keynote Speaker at  the  Ni nth Asi an Test  Sympos i um  Vi . Hi s  current VLSI  CAD research i nterest s  i n December 2000. Duri ng 1989 and 1990.he served  and 20031 nati onal  

on the Board of   Governors of   the I EEE Computer  S0 

are automati c m ed— si gnal   ci rcul t  test. pattern genera-  

ci et y.and i n 1994.chai red the Fel l ow Sel ecti on Com.  

ti on,bui l t —i n  sel f - testi ng,s ynthesi s  or f  testabi l i ty,f aul t  

mi t tee  of  that Soci et y.He ha s  recei ved s even Best  Pa-  

model i ng f or  nano- technol ogy,and l ow-power  desi gn.  

per  Awards  and one Honorabl e  M enti on Paper  Award.  

[ h t t p: / / www. e c e . r u t g e r s . e du / d i r e c t o r y / bu s h n e l 1 . h t m1 ]  

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