Department of Electrical and Computer Engineering COEN 451 April 25, 2008

Transcription

1 Deparme of Elecrical ad ompuer Egieerig OEN 45 April 5, 008 Aswer all Quesios. All Quesios carry equal marks Exam Duraio 3 hour You may use he crib shee ad MOSIS5B parameers aached. Oly recommeded calculaors are allowed. No cell phoes are allowed eve if hey are off. No books, papers are allowed. =============================================================== Quesio I his quesio he MOS rasisors have he followig parameers: NMOS TO = 0.6, T OX = 00A o, o =550cm /-sec, =0.6 /, j=7.0x0-4 F/m, jsw =.5EX0-0 F/m, = , s=-0.6. PMOS TO = -0.6, T OX = 00A o, o =50cm /-sec, =0.6 /, j=7.0x0-4 F/m, jsw =.5X0-0 F/m, = , s= 0.6. a. osruc a omplex MOS gae a he rasisor level for he followig fucio: F (A,B,,D) = AB + + D Assume you have double rail (ipus ad heir complemes are available). b. Deermie widh of all rasisors (i erms of, mi ) for equal rise ad fall ime a he oupu. c. Assume all rasisors have equal L ad equal /L = 4. A ipu paer of A=B==D= 0 is applied o he gae, deermie he pull dow resisace. d. ha would he pull dow resisace be, if he ipu paer of A=B== 0, D= is applied o he gae. Page of 7 OEN 45 ier 008

2 Quesio A egieer wishes o submi he layou show i Fig. Q for fabricaio usig N-well hree- layer meal process: a. Draw he verical cross secio B-B showig (aoae) all layers ad maerial ivolved. b. Lis he sequece of seps up he formaio of meal coacs required o fabricae he PMOS rasisor i he argeed echology. c. How may layers of meal appear i he layou of Fig. Q d. The egieer made wo layou errors. Ideify hese errors Fig. Q Layou o be submied Page of 7 OEN 45 ier 008

3 Quesio 3 eferrig o circui show i Fig. Q3 a). ha ype of MOS circui is his? b). ha are he advaages of such a circui? c). ha is he fucio a ode Y? d) a you cascade such a block for proper operaio? If o wha are he remedies ha ca be adoped? e) hy do you eed o calculae he miimum frequecy ad how would you calculae i? d). Derive he maximum operaig frequecy for he clock sigal. Use Time osa aalysis, ad i & j for he esisaces ad apaciaces a differe odes. ( eg. A for Trasisor A ad AD for apaciace bewee rasisors A & D) f). Usig a similar srucure ad oher blocks eeded, cosruc he rasisor diagram of a circui which ca be coeced a he oupu of he circui of Figure Q3 o geerae he fucio: S = Y + GH + K Fig. 3 ircui uder ivesigaio Page 3 of 7 OEN 45 ier 008

4 Quesio 4 The NMOS rasisor used i his quesio has he followig model parameers: TO = 0.6, T OX = 00A o, o =550cm /-sec, =0.6 /, = , s=-0.6. I he circui of Figure Q4, deermie:. The hreshold volage of he NMOS rasisor.. The regio of operaio of he rasisor. 3. The /L of he rasisor. 4. Deermie he OL of he circui ad draw he T curve. = 5 ma Fig. Q4 Quesio 5. I or 3 lies Defie or Explai he followig:. ha is ad Groud bouce?. ha is Field Oxide used for? 3. ha is he differece bewee he silico used for rasisor gae ad he silico used i he subsrae? 4. ha is elociy Sauraio? 5. ha is Mobiliy Degradaio? 6. ha is puch hrough pheomea? 7. ha is surface iversio? 8. ha is he differece bewee Lach ad Flip Flop? 9. ha is Frigig apaciace? 0. How he delay of a lie is relaed o is legh? Page 4 of 7 OEN 45 ier 008

5 Quesio 6 A Egieer has o desig a muli-sage buffer o coec he oupu of a sadard MOS iverer o a large exeral capaciive load of L=50pF. This iverer is marked wih he symbol X i Fig. Q6 has a delay of s ad has he followig parameers: =3.3 TN =- TP =0.33 K N =K P =00 A/ p= m = m L=Lp=0.5 m = 6.66fF/ m d=4.8g (a) Show ha he ipu capaciace g of X iverer equals o 0fF. (b) Fid he opimal scalig raio S op of he buffer circui. (c) Fid he umber of sages (N) required for he buffer circui. (d) alculae he oal delay p bewee pois A ad. (e) Deermie he curre sikig i L whe poi is a 0. N-Sage Buffer X A B g L =50 pf Fig. Q6 Page 5 of 7 OEN 45 ier 008

6 MOSIS5 Desig Ki..MODEL MOSN mos3 ype= +PHI= TOX=9.6000E-09 XJ= U TPG= +TO= DELTA=6.900E-0 LD=4.790E-08 KP=.9647E 04 +UO=546. THETA=.6840E-0 SH=3.50E+0 GAMMA= NSUB=.390E+7 NFS=5.9090E+ MAX=.0080E+05 +ETA=3.780E-0 +KAPPA=.8980E-0 GDO=3.055E-0 GSO=3.055E-0 +GBO=4.039E-0 J=5.6E-04 MJ=0.559 JS=5.00E- +MJS=0.5 PB=0.99 +X=4.08E-07 +APMOD=bsim XQ=0.5 XPAT=0.5 *eff = draw - Dela_ *The suggesed Dela_ is 4.080E-07.MODEL MOSP mos3 ype=p +PHI= TOX=9.6000E-09 XJ= U TPG=- +TO=-0.93 DELTA=.8750E-0 LD=3.5070E-08 KP=4.8740E-5 +UO=35.5 THETA=.8070E-0 SH=.000E-0 GAMMA= NSUB=8.50E+6 NFS=6.5000E+ MAX=.540E+05 ETA=.4500E-0 +KAPPA=7.9580E+00 GDO=.3933E-0 GSO=.39E-0 +GBO=3.7579E-0 J=9.35E-04 MJ=0.468 JS=.89E-0 MJS=0.505 PB=0.99 +X=3.6E-07 +APMOD=bsim XQ=0.5 XPAT=0.5 *eff = draw Dela_ *The suggesed Dela_ is 3.0E-07 Page 6 of 7 OEN 45 ier 008

7 I DSN N TO GSN TO TN qd I DSN Aex A Equaios ad cosas DSN I DSP T TO P GSP SB TP S DSP S DSP N GSN TN I DSN DS sh DSN K K L GS l w T DS P GSP TP I DSP Sh q p p q (Liear) DS (Sauraio) g L j JS perimeer J area GS T DSP x L 0. f l 9 0 N L p 0. r l 9 0 p p p P L TN TP PHL l 3 4 N L p p p PLH l 3 4 p p NM NM p H L TN N P TP OH IL IL OL = pf/cm q=.6x0-9 Page 7 of 7 OEN 45 ier 008

8 Appedix B T Parameers OH OL 0 IL IH X IL IH ( k ( ( ( x ) ) 3 3 p p p ) ) ( ( ( ( ) ) p p ) ) Page 8 of 7 OEN 45 ier 008

9 Soluio of he Exam Fial. ier 08 Quesio Q.a F { A, B,, D} AB D F AB D AB D ( A B) D Q.b 550 r 3.66, mi, process smalles widh, Pull dow has 3 50 p series rasisors, he A = 3 mi, = B,, D. For pull-up he wors codiio is series rasisors { p, A * r * wmi, 7. p, B p, p, D rwmi, 3. 6 mi, mi, *alues are muliple of mi, *Trasisors are arraged for beer fall ime. Page 9 of 7 OEN 45 ier 008

10 . Q.c Ipu A=B==D=0 A B D Pull dow resisace = + D +( A // B ) = / here is he resisace of oe rasisor wih /L = 4 [ ) ] * 4*( ) gs ds 0 Assumig =0.6 ad he effecs of SB are igored & DS is small eough o be igored, 0.345PF / cm 00A *0 F / m *550 *0 *0.37K o 4 * 4 * *3.45 *55 Pull dow resisace.5* K Page 0 of 7 OEN 45 ier 008

11 Q.d Ipu A=B==0 D= A B, D 0 Pull dow resisace would be ifiiy ad ope circui o groud. Quesio Q.a Page of 7 OEN 45 ier 008

12 Q.b Phoolihography sep o creae well Phoolihography sep o creae hi ide 3 Phoolihography sep o deposi Poly silico 4 Phoolihography sep o diffuse P+ silico creae Acive area 5 Phoolihography sep deposi SiO 6 Phoolihography sep o remove SiO where coacs are made ope coac area * SiO Deposiio separae all layers Q.c Layers Q.d ) Gae exesio for P rasisor missig ) Subsrae coecio o dd should be + Quesio 3 Q3 I he wors case Toal.{ D ( ( E ( A ( B AD AD A A B B ( AE AE D ) ) A A B B ) ) AD AE BA A ) ors case is whe A= D= =, he f, max(, ) T T T charge eval T Q3 Or we ca use a p-block Page of 7 OEN 45 ier 008

13 Q3 a. This circui is a Dyamic circui b. Has ihere pipeliig srucure Area is reduced i compariso o MOS urre ad power is reduced as o shor-circui curre is prese Fas speed c. Y= whe = = A ( D E) B d. This circui cao be cascaded because he oupu will rigger he ex block dischargig oupu ode i wrog ime. To remedy, oe ca follow he circui by a saic iverer or use a P-N-N-P blocks i cascade or use MOS o repea he blocks. e. If he frequecy is oo low, we risk losig he oupu charge hrough leakage curre. y mus o drop below IL of he ex block by he ed of evaluaio period. I wors case for low frequecy ou = + dp + s, where dp ad s are for all ipu rasisors. The ou ( - IL )=I leakage x ad F mi =I leakage /- ou ( IL - ) f. Max frequecy = F=/T where T=max(T charge, T eval ) I he wors case, T charge =.{ ( ) p A B AD AE D E B Quesio 4 Q4, SB ma(500 ) T T 0 ( SB S S Q4, ( ) T drai gs gs ds? gs (ma)(300) 4.4 ma(500 ) 4 h Trasisor O Trasisor is i Sauraio regio Page 3 of 7 OEN 45 ier 008

14 Q4, 3 i I ds DS K' ma, 80 A / [( gs k' ( ) L ) ( ds (550cm )] / sec)(0.345 pf / cm) 8 00 *0 cm *0 *0 ( ) L 3 3 *90( )[(4 0.9) ( L 95( )[(3.) * (.)] L *3.4)] Q4, 4 OL is obaied whe g =5 OL = 5-(mA)(300 ) = 4.4 he i =0, Trasisor is off OH =5ol Page 4 of 7 OEN 45 ier 008

15 Quesio 5 Q5 ) dd ad gd bouce are rasie effecs due o L di/d ha occurs o dd ad groud busses due o heavy supply curre i shor ime. ) The F OX or field ide is used o isolae differe pars of he I o preve hem from ieracig wih each oher. 3) The silico used i he gae is polysilico ad has greaer coducace. The subsrae is usually irisic silico, a semicoducor. 4) This is a poi whe icreasig he Elecric field desiy has o effec o he speed of he carriers. 5) This is a poi whe mobiliy has o loger a liear relaioship wih he Elecric field ad velociy. 6) Puch hrough effec is whe he drai volage is icreased o a poi ha he depleio regio exeds o ear he source (desiaio) ad elecros are ijeced direcly io he source. 7) This is a poi whe surface charge chages polariy ad becomes he same as he source ad drai. 8) A lach is level depeda while he Flip-Flop is edge depeda. 9) I is he capaciace due o he edge of he wire o he subsrae below a isolaio. 0) The delay is relaed o he square of he legh l. Page 5 of 7 OEN 45 ier 008

16 Quesio 6. a) g 0 ff L ( )(0.5)(6.66) p L p ()(0.5)0.66 b) Delay S * N * o Also S N Y, where S is he scalig facor of he apered buffer, N is he umber of sages ad Y is he load raio. N l S = l Y S l S l Y d ds 0 l s or l s (l Y, s o l s s ) s l s e o Page 6 of 7 OEN 45 ier 008

17 c) Y S N l i Y 50 pf 48 ff 04 e N N 04 7Sages d) Delay = SN =.7*7*S S 40S Buffer A o B e) alculaig he curre sikig io Las Sage ou = L + d,7 + dp,7 = L + 3 d 7 = L /S=50pF/e 8.4 pf (apprimae value) ca be calculaed as follows, assumig he effecs of db is The las sage is L egligible ad 8.4pF represes he ipu capaciace of he 7 h sage. 8.4 pf 8.4*0 L 3 9 ( L 6.66 *3* L & Las sage is i Liear egio L ) 84 I d K' ( gs ) ds L 84 I d 00 * ( ) * ma Page 7 of 7 OEN 45 ier 008