Cng ngh MOS (Metal Oxide Semiconductor-kim loi oxit bn dn) c tn gi xut x t cu trc MOS c bn ca mt in cc nm trn lp oxit cch nhit, di lp oxit l bn dn. Transistor trong cng ngh MOS l transistor hiu ng trng, gi l MOSFET (metal oxide silicon field effect transistor). C ngha in trng pha in cc kim loi ca lp oxit cch nhit c nh hng n in tr ca . Phn nhiu IC s MOS c thit k ht bng MOSFET, khng cn n linh kin no khc. u im chnh ca MOSFET l d ch to, ph tn thp, c nh, tiu hao rt t in nng. K thut lm IC MOS ch rc ri bng 1/3 k thut lm IC lng cc (TTL, ECL,...). Thm vo , thit b MOS chim t ch trn chip hn so vi BJT, thng thng, mi MOSFET ch cn 1 mi li vung din tch chip, trong khi BJT i hi khong 50 mi li vung. Quan trng hn, IC s MOS thng khng dng cc thnh phn in tr trong IC, vn chim qu nhiu din tch chip trong IC lng cc. V vy, IC MOS c th dung np nhiu phn t mch trn 1 chip n hn so vi IC lng cc. Bng chng l ta s thy MOS dng nhiu trong vi mch tch hp c LSI, VLSI hn hn TTL. Mt tch hp cao ca IC MOS lm chng c bit thch hp cho cc IC phc tp, nh chip vi x l v chip nh. Sa i trong cng ngh IC MOS cho ra nhng thit b nhanh hn 74, 74LS ca TTL, vi c im iu khin dng gn nh nhau. Do vy, thit b MOS c bit l CMOS c s dng kh rng ri trong mch MSI mc d tc c thua cc IC TTL cao cp v d b h hng do b tnh in. Mch s dng MOSFET c chia thnh 3 nhm l: - PMOS dng MOSFET knh P - NMOS dng MOSFET knh N tng cng - CMOS (MOS b) dng c 2 thit b knh P v knh N Cc IC s PMOS v NMOS c mt ng gi ln hn (nhiu transistor trong 1 chip hn) v do kinh t hn CMOS. NMOS c mt ng gi gn gp i PMOS. Ngoi ra, NMOS cng nhanh gn gp 2 ln PMOS, nh d kin cc in t t do l nhng ht ti dng trong NMOS, cn cc l trng (in tch dng chuyn ng chm hn) l ht ti dng cho PMOS. CMOS rc ri nht v c mt ng gi thp nht trong cc h MOS, nhng n c im mnh l tc cao hn v cng sut tiu th thp hn. IC NMOS v CMOS c dng rng ri trong lnh vc k thut s, nhng IC PMOS khng cn gp mt trong cc thit k mi na. Tuy nhin MOSFET knh P vn rt quan trng bi v chng c dng trong mch CMOS. Trc khi i vo cng ngh CMOS ta hy tm hiu qua v NMOS. Cng cn phi bit rng PMOS tng ng cng ging ht NMOS, ch khc chiu in p. Hnh 1.64 l cu to ca 1 cng NOT loi NMOS c bn

Mch gm 2 MOSFET: Q2 lm chuyn mch cn Q1 lm ti c nh v lun dn, in tr ca Q1 khong 100 k Ng vo mch t cc G ca Q2, cn ng ra ly im chung ca cc S Q1 v cc D Q2. Ngun phn cc cho mch gi s dng 5V. Khi Vin = 5 V, ng vo mc cao kch cho Q2 dn, tr trn Q2 cn khong 1K cu phn p gia RQ1 v RQ2 cho php p ra cn khong 0,05V tc l ng ra mc thp Khi Vin = 0V, ng vo mc thp, Q2 ngt, tr trn n kh ln khong 1010 ohm. Cu phn p RQ1 v RQ2 s t p ng ra xp x ngun, tc l ng ra mc cao. Vy mch hot ng nh mt cng NOT. Cng NOT c xem l mch c bn nht ca cng ngh MOS. Nu ta thm Q3 mc ni tip v ging vi Q2 th s c cng NAND. Nu ta mc Q3 song song v ging vi Q2 th s c cng NOR. Cng AND v cng OR c to ra bng cch thm cng NOT ng ra ca cng NAND v cng NOR va c to ra. Nh ni trc, NMOS khng phi to ra cc cng m thng dng xy dng mch t hp, mch tun t quy m thng c MSI tr ln, nhng tt c nhng mch v c bn vn ch l t hp ca cc mch cng logic c k ra y. Mt s c im ca NMOS : Tc chuyn mch: chm hn so vi loi TTL do in tr u vo kh cao ng thi b nh hng bi ti dung tnh m n thc Gii hn nhiu khong 1,5V vi ngun 5V v s tng t l khi ngun cp tng. Nh vy l tnh khng nhiu km hn TTL H s ti: v l thuyt l rt ln do tr u vo ca mch rt ln, tuy nhin, nu tn s hot ng cng cao (trn 100KHz) th in dung sinh ra c th lm suy gim thi gian chuyn mch ko theo gim kh nng giao tip ti. So vi TTL th NMOS vn c h s ti cao hn hn trung bnh l 50 cng cng loi. Cng sut tiu tn: y l u im ni bt ca logic MOS. Tht vy, chng hn vi cng NOT trn khi u vo thp RQ1 = 100k, RQ2 = 1010ohm nn dng tiu th I = V/R = 0,5nA => P =U.I = 2,5nW Khi u vo cao RQ1 = 100k, RQ2 1k nn dng tiu th I = V/R = 50uA 0,25mW

Vy cng sut trung bnh ch cao hn 0,1 mW mt cht, so vi TTL th n qu nh. Chnh nh u im ny m CMOS c th tch hp c LSI v VLSI, ni m nhiu cng, nhiu flip flop, nhiu mch khc c tch hp trong mt chp m khng sinh ra nhit ln lm hng chip. Cng cn lu l logic MOS do u c xy dng t cc transistor MOSFET nn rt nhy tnh in, phn sau ta s cp chi tit n vn ny.

CMOS2.1 Cu to

CMOS (Complementary MOS) c cu to kt hp c PMOS v NMOS trong cng 1 mch nh tn dng c cc th mnh ca c 2 loi, ni chung l nhanh hn ng thi mt mt nng lng cn thp hn so vi khi dng ri tng loi mt. Cu to c bn nht ca CMOS cng l mt cng NOT gm mt transistor NMOS v mt transistor PMOS nh hnh 1.65

Hot ng ca mch cng tng t nh NMOS Khi ng vo (ni chung cc cng 2 transistor) cao th ch c Q1 dn mnh do p ra ly t im chung ca 2 cc mng ca 2 transistor s xp x 0V nn ng ra thp. Khi ng vo thp Q1 s ngt cn Q2 dn mnh, p ra xp x ngun, tc ng ra mc cao. l khc vi cng NOT ca NMOS, y 2 transistor khng dn cng mt lc nn khng c dng in t ngun qua 2 transistor xung mass nh cng sut tiu tn gn nh bng 0. Tuy nhin khi

2 transistor ang chuyn mch v khi c ti th s c dng in chy qua mt hay c 2 transistor nn khi ny cng sut tiu tn li tng ln. Trn nguyn tc cng o, cng ging nh trc bng cch mc song song hay ni tip thm transistor ta c th thc hin c cc cng logic khc (hnh 1.66). Chng hn mc chng 2 NMOS v mc song song 2 PMOS ta c cng NAND. Cn khi mc chng 2 PMOS v mc song song 2 NMOS ta c cng NOR.

2.2 Phn loi C nhiu loi IC logic CMOS vi cch ng v (package) v chn ra ging nh cc IC loi TTL. Cc IC c quy m tch hp nh SSI v DIP (dual inline package): vi hai hng chn thng hng 14 hay 16 c dng ph bin. CMOS c h 4000, 4500 Hng RCA ca M cho ra i loi CMOS u tin ly tn CD4000A. V sau RCA c ci tin cho ra lot CD4000B c thm tng m ra, sau ny hng li b sung thm lot CD4500, CD4700. Hng Motorola (M) sau cng cho ra lot CMOS MC14000, MC14000B, MC14500 tng thch vi sn phm c ca RCA. c im chung ca lot ny l :

in p ngun cung cp t 3V n 18V m thng nht l t 5 n 15 V. Chng c cng sut tiu hao nh Ring loi 4000B do c thm tng m ra nn dng ra ln hn, khng nhiu tt hn m tc cng nhanh hn loi 4000A trc .

Tuy nhin cc loi trn v tc th t ra kh chm chp v dng cng nh hn nhiu so vi cc loi TTL v CMOS khc. Chnh v vy chng khng c s dng rng ri cc thit k hin i.Loi 74CXX y l loi CMOS c sn xut ra tng thch vi cc loi TTL v nhiu mt nh chc nng, chn ra nhng khon ngun nui th rng hn. Cc c tnh ca loi ny tt hn loi CMOS trc mt cht tuy nhin n li t c s dng do c nhiu loi CMOS sau thay th loi CMOS tc cao 74HCXX v 74HCTXX. y l 2 loi CMOS c pht trin t 74CXX. 74HCXX c dng ra ln v tc nhanh hn hn 74CXX, tc ca n tng ng vi loi 74LSXX, nhng cng sut tiu tn th thp hn. Ngun cho n l t 2V n 6V. Cn 74HCTXX chnh l 74HCXX nhng tng thch vi TTL nhiu hn nh ngun vo gn ging TTL : 4,5V n 5,5V. Do 74HCTXX c th thay th trc tip cho 74LSXX v giao tip vi cc loi TTL rt bnh thng. Ngy nay 74HC v 74HCT tr thnh loi CMOS hay dng nht m li c th thay th trc tip cho loi TTL thng dng. Loi CMOS tin tin 74AC, 74ACT Loi ny c ch to ra c nhiu ci tin cng ging nh bn TTL, n s hn hn cc loi trc nhng vic s dng cn hn ch cng vn l do gi thnh cn cao. Chng hn cu trc mch v chn ra c sp xp hp l gip gim nhng nh hng gia cc ng tn hiu vo ra do chn ra ca 2 loi ny khc vi chn ra ca TTL. Khng nhiu, tr hon truyn, tc ng h ti a u hn hn loi 74HC, 74HCT. K hiu ca chng hi khc mt cht nh 74AC11004 l tng ng vi 74HC04. 74ACT11293 l tng ng vi 74HCT293. Loi CMOS tc cao FACT y l sn phm ca hng Fairchild, loi ny c tnh nng tri hn cc sn phm tng ng c. Loi CMOS tc cao tin tin 74AHC, 74AHCT y l sn phm mi c nhng ci tin t loi 74HC v 74HCT, chng tn dng c c 2 u im ln nht ca TTL l tc cao v ca CMOS l tiu tn thp do c th thay th trc tip cho 74HC v 74HCT. Bng sau cho php so snh cng sut tiu tn v tr hon truyn ca cc loi TTL v CMOS ngun cp in 5V.

Ngoi cc loi trn cng ngh CMOS cng pht trin mt s loi mi gm: BiCMOS y l sn phm kt hp cng ngh lng cc TTL vi cng ngh CMOS nh tn dng c c 2 u im ca 2 cng ngh l tc nhanh v cng sut tiu tn thp. N gim c 75% cng sut tiu tn so vi loi 74F trong lc vn gi c tc v c im iu khin tng ng. N cng c chn ra tng thch vi TTL v hot ng p ngun 5V. Tuy nhin Bi CMOS thng ch c tch hp quy m va v ln dng nhiu trong giao din vi x l v b nh, nh mch cht, b m, b iu khin hay b thu pht. Loi CMOS in th thp y l loi CMOS kh c bit c p ngun gim xung ch cn khong 3V. Khi p gim s ko theo gim cng sut tiu tn bn trong mch nh mt tch hp ca mch tng ln, ri tc chuyn mch cng tng ln iu ny rt cn thit trong cc b vi x l b nh ... vi quy m tch hp VLSI. Cng c kh nhiu loi CMOS p thp, v y l xu hng ca mai sau, y ch ni qua v mt s loi ca hng Texas Instruments 74LV (low voltage) : l lot CMOS in th thp tng ng vi cc vi mch s SSI v MSI ca cc cng ngh khc. N ch hot ng c vi cc vi mch 3,3V khc 74LVC (low voltage CMOS ) : gm rt nhiu mch SSI v MSI nh lot 74. N c th nhn mc 5V cc ng vo nn c th dng chuyn i cc h thng dng 5V sang dng 3,3V khc. Nu gi dng in ng ra thp in th ng ra nm trong 1 gii hn cho php, n cng c th giao tip vi cc ng vo TTL 5V. Tuy nhin p vo cao ca cc CMOS 5V nh 74HC hay 74AHC khin chng khng th iu khin t cc vi mch LVC 74ALVC (advanced low voltage CMOS ) : l lot CMOS in th thp, ch yu dng cho cc mch giao din bus hot ng 3,3V 74LVT (low voltage BiCMOS) : ging nh 74LVC c th hot ng logic 5V v c th dng nh mch s chuyn mc 5V sang 3V Bng sau so snh mt s c tnh ca cc loi CMOS p thp

CMOS cc mng h, CMOS ra 3 trng thi v CMOS ny schmitt trigger Tng t nh bn TTL, cc cng CMOS cng c cc loi ra h mng, ra 3 trng thi v ny schmitt trigger, v c nhiu loi CMOS c sn xut tng thch v thay th cho loi TTL tng ng. CMOS racc mng h Do dng MOSFET nn ng ra khng phi l cc thu m l cc mng hnh 1.67 trrnh by hai cng NOT CMOS thng c ng ra ni chung vi nhau

Nu 2 u vo cao th 2P ngt, 2N dn ng ra mc cao bnh thng. Nu 2 u vo thp th 2P dn, 2N ngt ng ra mc thp bnh thng. Nhng nu ng vo cng 1 thp cn ng vo cng 2 cao th P1 dn N1 ngt, P2 ngt N2 dn p ng ra s l na p ngun Vdd. p ny ri vo vng bt nh khng th dng kch cc ti c hn na vi p Vdd m cao, dng dn cao c th lm tiu 2 transistor ca cng. Vy cch cc D ra h l hp trong trng hp ny. Trong cu trc mch s khng cn MOSFET knh P na, cn MOSFET knh N s h cc mng D. Ta c th ni cc ng ra theo kiu ni AND hay OR v tt nhin l cng phi cn in tr ko ln to mc logic cao, gi tr ca R ko ln tnh ging nh bn mch loi TTL. CMOS ra 3 trng thi Tng t mch bn TTL, mch c thm ng iu khin G (hay C). G cao 2 cng nand ni, nn Y = A, ta c cng m khng o

G thp ng ra ca 2 cng nand ln cao lm PMOS v NMOS cng ngng dn v y l trng thi th 3 hay cn gi l trng thi tr khng cao (high Z), lc by gi t ng ra Y nhn ngc vo mch th mch nh khng c (in tr ng ra Y ln ngun v xung mass u rt ln). Ng G cng c th tc ng mc thp K hiu logic ca mch

Cng ny schmitt trigger tng t ny schmitt trigger bn mch TTL Cng truyn dn CMOS (transmission gate :TG)y l loi cng logic m bn cng ngh lng cc khng c; cng truyn dn hot ng nh mt cng tc ng m (s) cho php d liu (dng s) truyn qua li theo c 2 chiu. Trc ht l cu to ca cng truyn NMOS

Tn hiu truyn c th l tng t hay s min nm trong khong 0 n Vdd. Nhng y d minh ho ta gi s ly ngun cp l 10V, p ngng ca NMOS s l 2V Khi ng vo thp, t s khng c np nn tt nhin ng ra cng l mc thp

Khi ng vo cao m ng khin G vn thp th ng ra cng vn thp Khi ng vo cao v G cao => NMOS dn vi p ngng 2V nn t np y n 8V th NMOS ngt, ng ra c th hiu l mc cao, do tn hiu c truyn t tri sang phi Khi ny m ng vo xung mc thp th t s x qua NMOS do ng ra ln cao tr li tc l d liu truyn t phi sang tri Tuy nhin ta c nhn xt l, khi b truyn nh vy d liu gim bin i mt 2V. Vi mch s c th vn hiu l mc cao mc thp, cn vi mch tng t th nh vy l mt mt nng lng nhiu ri, v n cn b nh hng nng hn khi nhiu cng truyn mc ni tip nhau. Cng truyn CMOS : Hnh 1.70 cho thy cu trc ca 1 cng truyn CMOS c bn dng 1 NMOS v 1PMOS mc song song, cng vi nhng gi s nh trn bn s thy CMOS khc phc c im d ca NMOS v chnh n c s dng rng ri ngy nay.

Khi G thp, khng cho php truyn. Khi G cao, nu ng vo thp ng ra khng c g thay i. Cn nu ng vo cao th c 2 transistor u dn d liu truyn t tri sang phi np cho t, ng ra mc cao nhng c 1 im khc y l khi t np n 8V th NMOS ngt trong khi PMOS vn dn mnh lm t np 10V. Khi ng ra ang 10V, ng G vn cao m ng vo xung thp th t s x ngc tr li qua 2 transistor lm ng vo ln cao tr li. Cc k hiu cho cng truyn nh hnh

2.3 c tnh k thut

Cng sut tiu tn Khi mch CMOS trng thi tnh (khng chuyn mch) th cng sut tiu tn PD ca mch rt nh. C th thy iu ny khi phn tch mch mch cng nand hay nor trc. Vi ngun 5V, PD ca mi cng ch khong 2,5nW. Tuy nhin PD s gia tng ng k khi cng CMOS phi chuyn mch nhanh. Chng hn tn s chuyn mch l 100KHz th PD l 10 nW, cn f=1MHz th PD= 0,1mW. n tn s c 2 hay 3 MHz l PD ca CMOS tng ng vi PD ca 74LS bn TTL, tc l mt dn i u th ca mnh. L do c iu ny l v khi chuyn mch c 2 transistor u dn khin dng b ht mnh cp cho ph ti l cc in dung (sinh ra cc xung nhn lm bin ca dng b y ln c khi c 5mA v thi gian tn ti khong 20 n 30 ns). Tn s chuyn mch cng ln th sinh ra nhiu xung nhn lm I cng tng ko theo P tng theo. P y chnh l cng sut ng lu tr in dung ti. in dung y bao gm cc in dung u vo kt hp ca bt k ti no ang c kch thch v in dung u ra ring ca thit b.

Tc chuyn mch (tn s chuyn mch) Cng ging nh cc mch TTL, mch CMOS cng phi c tr hon truyn thc hin chuyn mch. Nu tr hon ny lm tPH bng

na chu k tn hiu vo th dng song vung s tr thnh xung tam gic khin mch c th mt tc dng logic Tuy nhin tc chuyn mch ca CMOS th nhanh hn hn loi TTL do in tr u ra thp mi trng thi. Tc chuyn mch s tng ln khi tng ngun nhng iu ny cng s lm tng cng sut tiu tn, ngoi ra n cng cn nh hng bi ti in dung. Gii hn tc chuyn mch cho php lm nn tn s chuyn mch ti a c tnh da trn tPH. Bng sau cho php so snh fmax ca mt s loi cng nand loi TTL vi CMOS

Trong vic s dng cc IC logic CMOS ta phi bit nhiu c tnh v gii hn ca chng. Cc c tnh thng dng nh p nui, s to ra, kh nng dng ra,... thng d vn dng. Tt c cc IC logic u dng c ngun nui 5V. S to ra vi cng loi logic t nht l gn chc trong lc thng ch cn vi. Tuy nhin i khi c nghi ng hay s dng trng hp p cp Vmax, fmax, ti thun dung thun cm... hay giao tip gia cc IC khc loi, khc p ngun, ni chung l cc trng hp c bit. th ta phi tham kho ti liu data sheet hay data book. Cng nh bn TTL, mt s c tnh chnh ca CMOS c ni n y l: p ngun nui k hiu l Vdd (khc vi bn TTL k hiu l Vcc) rt khc nhau do cn rt cn thn vi n, c th dng ngun 5V l tt nht. Bng sau a ra cc khong p ngun cho tng loi CMOS.

in p vo v ra ca cc loi CMOS Cng ging nh bn TTL v k hiu, tn gi nhng bn CMOS c phc tp hn do ngun nui cho cc loi IC th khc nhau, ta ch c th rt ra tng i iu kin ngun Vdd = 5V. Hnh v bng di

nu ra cc thng s p ra v vo. Ring loi 74HCT l CMOS tc cao tng thch vi TTL nn thng s cng ging nh bn TTL.

Dng in ng vo v ng ra bng so snh dng vo ra ca mt s loi CMOS vi mt s loi TTL

Ni chung ta quan tm n dng ra nhiu hn v l dng ra max cho php m vn m bo cc mc logic ra ng nh phn trn. Cn cc p ra cng ch quan tm khi tnh n vic giao tip cng khc loi khc p nui. H s ti Dng ra ca cc CMOS kh ln trong lc in tr vo ca cc CMOS li rt ln (thng khong 1012 ohm) tc dng vo rt rt nh nn

s to ra rt ln. Nhng mi cng CMOS c in dung ng vo thng cng khong 5pF nn khi c nhiu cng ti mc song song s in dung tng ln lm tc chuyn mch chm li khin s to ra tn s thp (di 1MHz) l vi chc, cn tn s cao s to ra gim ch cn di 10. Tnh khng nhiu V c tnh chuyn (trng thi) ni chung cc loi CMOS u chuyn trng thi kh dt khot tr loi 4000A bi v chng c tng m trc ng ra V gii hn nhiu ni chung l tt hn cc loi TTL. Tt nht l loi 4000A,B. Gii hn nhiu s cn tt hn nu ta tng ngun nui ln hn 5V, tuy nhin lc ny tn hao cng v th tng theo. Cch tnh l nhiu mc cao v mc thp vn nh trc, tc l: VNH = VOH(min) VIH(min) VNL = VIL(max) VIH(max) CC IC CNG LOGIC C rt nhiu IC loi CMOS c m s v chc nng logic tng t nh cc IC TTL chng hn bn TTL IC 4 cng nand 2 ng vo l 7400, 74LS00, 74AS00,... th bn CMOS cng tng t c 74C00, 74HC/HCT00, 74AC11000,... Tuy nhin khng phi tt c bn TTL c th bn CMOS cng c. CMOS cng cn c nhng loi ring, chng hn vi cng ny schmitt trigger ngoi 74HC/HCT14 gm 6 cng o, 74HC/HCT132 gm 4 cng nand 2 ng vo cn c 4014, 4534 cng gm 6 cng o, 4093 cng gm 4 cng nand 2 ng vo; hay 4066 l cng truyn 2 chiu s tng t vv... Hnh 1.74 l s chn ra ca mt s cng logic loi 4000 cng hay dng