static principle: output determined by a connection with strong node dynamic principle: output (sometimes) determined by a weak (floating) node

Transcription

1 stti n ynmi priniple pmos network nmos network v out stti priniple: output etermine y onnetion with strong noe ynmi priniple: output (sometimes) etermine y wek (floting) noe hrging: C s is eing hrge up to V + - level evlution: C s is eing ishrge when there is onuting pth to mss ontrol hrging with levels evlution pss network C s

2 relistion of ynmi logi P "prehrge" swith P prehrge swith P pss network C s N C s N C s N evlution swith pss network pss evlution network swith ontrol with levels interhnge network n evlution swith toggle swith eomes seletor pss network C s

3 mos-relistion of ynmi logi P pss network N "prehrge" swith C s evlution swith v uit V low: C s is eing hrge up to V + - level ("prehrge") high: C s is eing ishrge when the nmos network hs onuting pth; else: v out shifts slowly towrs n intermeite level T D v out prehrge evlution t

4 evlution spee T D 5 NOR(S) NAND(S) 4 NOR(S) 3 NAND(S) NAND(D) 2 NAND(S) NAND(D) NOR(S) NOR(D) # inputs NOR(D) fnout : inverter pmos evlution : spee 7.25/.75 of nmos ynmi logi : 4./.75 is fster, groun ut wht swith out :.5/.75 prehrge

5 hiing prehrge time slve lok p-e lok T S slve trnsprnt prehrge T P slve lthes omintoril logi mster lok mster trnsprnt T M mster lthes T M + stti logi: T S + mx T pth ( GATE ( S) ) T M + mx ynmi logi: ( T,T ) + mx T ( GATE ( D) ) S P pth D

6 the se prolem v out solutions:. "ummy" imittes the slowest gte ("self timing") ' ' ' must ome suffuiently lter thn otherwise spurious ishrge ours (ls ====)

7 no-re logi (nor) solutions: v out. "ummy" imittes the slowest gte ("self timing") 2. lternte nmos n pmos more omplite logi synthesis floting noe floting noe ' ' noise sensitivity euse of possily lrge floting noes n extr lok line -> re more pmos network (n therefore slower) e time for "skew" protetion (more ely, unless.... )

8 omino logi solutions: v out. "ummy" imittes the slowest gte ("self timing") 2. lternte nmos n pmos 3. invert the output only unte logi possile floting noe sense noe floting noe ' v out ' less noise sensitivity euse output from strong logi onentrte floting noe effet only when sense noe hnges >> Vt

9 omino logi prehrge: "sense noe" is eing hrge v sense V + ; v out V; nmos trnsistors in fnout o not onut! evlution: if "sense noe" is eing hrge v sense V ; v out V + ; trnsistors in fnout will open else v out stys low; nmos trnsistors in fnout still o not onut solutions:. "ummy" imittes the slowest gte ("self timing") 2. lternte nmos n pmos 3. invert the output only unte logi possile floting noe sense noe floting noe ' v out less noise sensitivity euse output from strong logi onentrte floting noe effet only when sense noe hnges >> Vt

10 hrge shring in omino logi t < t ti : v s = V+ < L t i H v i C s V s V out t >> t i : Q tot = C s V + ( ) Q tot = C s v s + C + when v s < C 2 v i v s v t H L L L C C 2 t : V + C s V v s + = C s + C + C 2 + V + C + C2 C s L H v s v s v i v s V IH C + C 2 V < C V + s IH V IH t t i t

11 hrge shring in omino logi reue hrge shring y: L t i H v i C s V s V out enlrging C s prehrging internl noes leeers H L L C leeer leeer L C 2 L H nmos network nmos network ll mesures ely evlution! smll, euse of rtio effet smll, forming skewe lth : esign!

12 omplementry network pirs in nmos soe swith is network etween two eision noes n strong noe with the property tht lwys extly one eision noe is eletrilly onnete with the strong noe. exmple: pull-own soe swith (strong noe is low). D 2 D e D 2 D soeswith e "pull-own soe swithes onsists of two omplementry networks (n-type swithes), ut now with the omplementry signls ontrolle.

13 ifferentil soe-swithes vrious pull-up possiilities for pull-own soe swithes D 2 D D 2 D D 2 D soeswith lthe ttention: low levels strong, ut high levels re wek! soe swith wek (pseuo-nmos) soe swith prehrge if low, thn D n D 2 high! if high, thn either D or D 2 low!

14 ifferentil soe swith Q Q Q Q soe swith e here too omplementry network! ut now: - oth nmost - omplementry signls neee e more wires, etter testility

15 from tle to eision igrm representtions of logi funtions minterms or mxterms truth tle sum of prouts or prout of sums ftore expressions... tree strutures

16 from tle to eision igrm representtions of logi funtions minterms or mxterms truth tle sum of prouts or prout of sums ftore expressions... tree strutures -- eh pth from the root to lef is minterm -- funtion vlue in lef

17 from tle to eision igrm from tle to eision igrm representtions of logi funtions minterms or mxterms truth tle sum of prouts or prout of sums ftore expressions... tree strutures -- eh pth from the root to lef is minterm -- funtion vlue in lef

18 from tle to eision igrm from tle to eision igrm vrile hs in the eliminte vriles with two ientil su trees! hs in the green su trees no impt: oes not isriminte"

19 from tle to eision igrm eliminte vriles with two ientil su trees! vrile is in the green su trees eliminte!

20 from tle to eision igrm eliminte vriles with two ientil su trees! vrile is in the green su trees eliminte! vriele hs in the green su tree no impt : oes not isriminte"

21 from tle to eision igrm eliminte vriles with two ientil su trees! vrile is in the green su tree eliminte

22 from tle to eision igrm. 2. eliminte vriles with two ientil su trees! ientify ientil su trees! the two green su trees re (inlusive lels) ientil!

23 from tle to eision igrm. 2. eliminte vriles with two ientil su trees! ientify ientil su trees! the two green su trees re (inlusive lels) ientifie!

24 from tle to eision igrm. 2. eliminte vriles with two ientil su trees! ientify ientil su trees! the igrm is no longer tree"! ("g" : irete yli grph ) vrile hs in the green su tree no impt: oes not isriminte"

25 from tle to eision igrm. 2. eliminte vriles with two ientil su trees! ientify ientil su trees! the igrm is no longer tree"! ("g" : irete yli grph ) vrile is in the green su tree eliminte!

26 from tle to eision igrm. 2. eliminte vriles with two ientil su trees! ientify ientil su trees! 3. ientify the - n -lefs! the igrm is no longer tree"! ("g" : irete yli grph )

27 from tle to eision igrm. 2. eliminte vriles with two ientil su trees! ientify ientil su trees! 3. ientify the - n -lefs! the igrm is no longer tree"! ("g" : irete yli grph ) fter ientifition of lefs the igrm hs only two lefs left!

28 from eision igrm to pss network reple x x y relistion is otine y repling every noe y 2-seletor (or pir of omplementry swithes) x

29 from eision igrm to pss network