low power ppt unit-1

8/16/2019 Low Power Ppt Unit-1

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215VLTO3-LOW POWER VLSI

CIRCUITS

UNIT-1 POWER DISSIPATION IN CMOS

OUTLINE

•HIERARCHY OF LIMITS OF POWER

•SOURCES OF POWER CONSUMPTION

•PHYSICS OF POWER DISSIPATION IN CMOS FET DEVICES

•BASIC PRINCIPLE OF LOW POWER DESIGN


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WHY LOW POWER ?

Users need for:◦ Mob!"#

◦ Por"$b!"#

◦ Re!$b!"# P$%&$'n' %os"s

Po(er s)**!# r$! des'n C+* $nd s#s"e, %oo!n' %os"s Gro("+ of b$""er#-*o(ered s#s"e,s Nose ,,)n"# $nd s#s"e, re!$b!"# B$""er# !fe .n *or"$b!e s#s"e,s/ En0ron,en"$! %on%erns


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LOW POWER DESIGN- Mo"0$"ons

Minimize powe

◦Red)%e *o(er n 0$ro)s ,odes of de0%e o*er$"on◦D#n$,% *o(er1 !e$&$'e *o(er1 or "o"$! *o(er

Minimize !ime

◦

Red)%e *o(er 2)%&!#◦Co,*!e"e "+e des'n n $s !""!e ",e $s *ossb!e

◦Pre0en" do(ns"re$, ss)es %$)sed b# LPD "e%+n2)es

◦A0od %o,*!%$"n' ",n' $nd f)n%"on$! 0erf%$"on

Minimize e""o!

◦Red)%e *o(er eff%en"!#

◦Co,*!e"e "+e des'n ("+ $s fe( reso)r%es $s *ossb!e

◦Pre0en" do(ns"re$, ss)es %$)sed b# LPD "e%+n2)es

◦

A0od %o,*!%$"n' ",n' $nd f)n%"on$! 0erf%$"on


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PRINCIPLES OF LOW-POWER DESIGN

Usn' "+e !o(es" *ossb!e s)**!# 0o!"$'e3

Usn' "+e s,$!!es" 'eo,e"r#1 +'+es" fre2)en%# de0%es b)" o*er$"n' "+e$" "+e !o(es" *ossb!e fre2)en%#3

Usn' *$r$!!e!s, $nd **e!nn' "o !o(er *o(er re2)red fre2)en%# ofo*er$"on

Po(er ,$n$'e,en" b# ds%onne%"n' "+e *o(er so)r%e (+en "+e s#s"e, sd!e3

Des'nn' s#s"e, "o +$0e !o(es" re2)re,en"s on s)bs#s"e, *erfor,$n%efor "+e '0en )ser !e0e! f)n%"on$!"#3


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MOORE4S LAW

Moore5s L$( ($s n"$!!# ,$de n "+e for, of $n obser0$"on $nd fore%$s"3 M$n %on%e*"s :

Dens"# of "r$nss"ors do)b!e e0er# "(o #e$rs3 Co,*!e6"# of "r$nss"ors for ,n,), %os" do)b!e e0er# #e$r3

T(o-M! s2)$res: Ab!"# "o b)!d 788 "r$nss"ors *er !ne$r n%+ or9781888 *er 2)$r"er n%+3

He$" Dss*$"on: Dre%" $%%ess "o +e$" 'ener$"n' so)r%es3 H'+ de0%e #e!d: No f)nd$,en"$! obs"$%!e "o $%+e0n' de0%e #e!d of

88;3


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Moore4s L$( Con". Moore


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HIERARCHY OF LIMITS OF POWER

P)*SICAL

DESI+N

CIRCUIT LEVEL

ARIT)EMATIC

LEVEL

AL+ORIT)MIC LEVEL

S*STEM LEVEL


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HIERARCHY OF LIMITS OF POWER

Le,e P$!i'&$ !$./.

S#s"e, Po(er do(n1 S#s"e, *$r""onn'

A!'or"+, Co,*!e6"#1 Lo%$!"#1 Con%)rren%#1Re')!$r"#1

D$"$ re*resen"$"onAr%+"e%")re Con%)rren%#1 Ins"r)%"on se" se!e%"on1

S'n$! %orre!$"on1 D$"$ re*resen"$"on

Cr%)"Lo'% Lo'% o*",$"on1 No0e! %r%)"s1Tr$nss"or sn'1 Vo!"$'e s!$nds

P+#s%$! Des'n Co,*$%" !$#o)"1 In"er%onne%"s

Te%+no!o'# SOI1 Ad0$n%ed *$%&$'n'


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O0er0e( of Po(er %ons),*"on

A0er$'e *o(er %ons),*"on D#n$,% *o(er %ons),*"on

S+or"-%r%)" *o(er %ons),*"on

Le$&$'e *o(er %ons),*"on

S"$"% *o(er %ons),*"on

So)res of *o(er %ons),*"on


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•Po(er Cons),*"on -L,"s "+e n),ber of "r$nss"ors on $ %+*3

P=P Switching

+P Short-Circuit

+P leakage.

SOURCES OF POWER CONSUMPTION

•PSwi!'0in 1 %$!!ed $!so s("%+n' *o(er1 s d)e "o %+$r'n' $nd ds%+$r'n'%$*$%"ors %r%)"3

•PS0o!-Ci'&i! 1 %$!!ed s+or"-%r%)" *o(er1 s %$)sed b# "+e s+or" %r%)"%)rren"s "+$" $rse of PMOSNMOS "r$nss"ors $re %ond)%"n's,)!"$neo)s!#3

•PLe$/$e 1 or'n$"es fro, s)bs"r$"e ne%"on $nd s)b"+res+o!d effe%"s3 For

o!der "e%+no , $nd $bo0e/1 PSwi!'0in

($s *redo,n$n"3 For dee*-

s)b,%ron *ro%esses1 PLe$/$e be%o,es ,*or"$n"3

De.in "o ow-powe impie. !0e $ii!( !o e#&'e $ !0ee 'omponen!.


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Tr$ns"on Po(er

G$"e o)"*)" rsn' "r$ns"on◦ Ener'# dss*$"ed n *MOS "r$nss"or CV 99◦ Ener'# s"ored n %$*$%"or CV 99

G$"e o)"*)" f$!!n' "r$ns"on◦

Ener'# dss*$"ed n nMOS "r$nss"or CV9

9 Ener'# dss*$"ed *er "r$ns"on CV 99

Powe #i..ip$!ion:

Ptotal = Pdyn + PstatPtran + Psc + Pstat


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SOURCES OF ENERGYCONSUMPTION


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SOURCES OF POWER DISSIPATION

SYSTEM POWER

DYNAMICPOWER

STATIC POWER

GATE POWER DISSIPATION

SWICTH

INGPOWER

SHORT-CIRCUI

T

LEAKAGEPOWER

GLICTHIN

G POWER


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PHYSICS OF POWER DISSIPATION IN CMOS FET DEVICES

D(n$mi' powe #i..ip$!ion.: W+ene0er "+e !o'% !e0e! %+$n'es $"dfferen" *on"s n "+e %r%)" be%$)se of "+e %+$n'e n "+e n*)" s'n$!s "+ed#n$,% *o(er dss*$"on o%%)rs.

◦ S("%+n' *o(er dss*$"on3

◦ S+or"-%r%)" *o(er dss*$"on3

S!$!i' powe#i..ip$!ion.: T+s s $ "#*e of dss*$"on1 (+%+ does no"

+$0e $n# effe%" of !e0e! %+$n'e n "+e n*)" $nd o)"*)"3

Le$/$e powe3 Lo( *o(er des'n (o)!d !oo& $" "+e "r$de offs of "+e $bo0e ss)es3

SOURES O POWER DISSIPATION

P 4 P .wi!'0in P .0o!-'i'&i! P e$/$e P .!$!i'


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POWER DISSIPATION


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P+#s%s of Po(er Dss*$"on n De0%es


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P+#s%s of Po(er Dss*$"on n CMOS FETDe0%es


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CMOS GATE POWER EUATIONS


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D#n$,% Po(er

D#n$,% *o(er s re2)red "o %+$r'e $nd ds%+$r'e !o$d %$*$%"$n%es (+en"r$nss"ors s("%+3

One %#%!e n0o!0es $ rsn' $nd f$!!n' o)"*)"3

On rsn' o)"*)"1 %+$r'e CVDD s re2)red On f$!!n' o)"*)"1 %+$r'e s d),*ed "o GND

T+s re*e$"s Tf s( ",es o0er $n n"er0$! of T

Cf sw

iDD(t)

VDD

9

d#n$,% DD P CV f α =


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D#n$,% Po(er Con".

Cf sw

iDD

(t)VDD

[ ]

d#n$,%

8

8

s(

9

s(

:. /

. /

T

DD DD

T DD

DD

DD DD

DD

P i t V dt T

V i t dt

T

V Tf CV

T

CV f

=

=

=

=

∫

∫

9

d#n$,% DD P CV f α =


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Lo(ern' D#n$,% Po(er

P#(n 4 CL VDD2 P6 1 "

C$*$%"$n%e:F)n%"on of f$n-o)"1 (re !en'"+1 "r$nss"or ses S)**!# Vo!"$'e:H$s been dro**n' ("+ s)%%ess0e 'ener$"ons

C!o%& fre2)en%#:

A%"0"# f$%"or:

Lowein CL• I,*ro0es *erfor,$n%e $s (e!!• ee* "r$nss"ors ,n,), se .&ee*s n"rns% %$*$%"$n%e .'$"e $nd dff)son/ s,$!!/• Tr$nss"ors s+o)!d be sed on!# (+en CL s do,n$"ed b# e6"rns% %$*$%"$n%e

.f$no)" $nd (res/

Re#&'in VDD 0$. $ %&$#$!i' e""e'!

• B)" +$s $ ne'$"0e effe%" on *erfor,$n%e es*e%$!!# $s VDD $**ro$%+es 9VT

Re#&'in !0e .wi!'0in $'!i,i!(7 " 6 1 4 P6 1 8 "

• A f)n%"on of s'n$! s"$"s"%s $nd %!o%& r$"e

• I,*$%"ed b# !o'% $nd $r%+"e%")re des'n de%sons


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S("%+n' Po(er Dss*$"on

P Swi'!0in 4CV2 "9 C$)sed b# "+e %+$r'n' $nd ds%+$r'n' of "+e node %$*$%"$n%e. CL s "+e o)"*)" !o$d of "+e '$"e1 VDD s "+e s)**!# 0o!"$'e1 " Co'/ s "+e %!o%& fre2)en% s

"+e s("%+n' $%"0"# of "+e '$"e1 defned $s "+e *rob$b!"# of "+e '$"e4s o)"*)" "o ,$"r$ns"on d)rn' one %!o%& %#%!e.

Figure 1: Switching power dissipation.


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S("%+n' Po(er Dss*$"on


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S("%+n' Po(er Dss*$"on %on"3

Re#&'!ion. o" PSwi!'0in $e $'0ie,$e (:

s)**!# 0o!"$'e s%$!n'fre2)en%# s%$!n',n,$"on of s("%+ed %$*$%"$n%e

P.;w 837 α CL Vdd9 f %!&

CL *+#s%$! %$*$%"$n%e1 Vdd s)**!# 0o!"$'e1 α s("%+n' $%"0"#1 f %!& %!o%&fre2)en%#3CL./ CIN J C(re J C *$r./

CIN "+e '$"e n*)" %$*$%"$n%e1 C(re "+e *$r$s"% n"er%onne%" $nd C *$r dff)son%$*$%"$n%es of e$%+ '$"e3Depen#. on:

◦ S)**!# 0o!"$'e◦ P+#s%$! C$*$%"$n%e◦ S("%+n' $%"0"#


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S+or" - %r%)" *o(er dss*$"on

W+en "r$nss"ors s("%+1 bo"+ nMOS $nd *MOS ne"(or&s ,$# be,o,en"$r!# ON $" on%e

Le$ds "o $ b!* of Ks+or" %r%)" %)rren"3

8; of d#n$,% *o(er f rsef$!! ",es $re %o,*$r$b!e for n*)"$nd o)"*)"

Ps% f %& Es%


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Copyrigh Agr!"!# $Sri%!h&' ())*

Lo"-Po"+r D+&ig, !, T+&'L+/r+ ( (0

S+or" - %r%)" *o(er dss*$"on

In%re$ses ("+ rse $nd f$!! ",es of n*)" De%re$ses for !$r'er o)"*)" !o$d %$*$%"$n%e

De%re$ses $nd e0en")$!!# be%o,es ero (+en V DD s s%$!ed do(n b)" "+e"+res+o!d 0o!"$'es $re no" s%$!ed do(n3

E scf tBt E V DD i sc.t /dt

.t E – t B/ I scmaxf V DD / 9

E scf t f .V DD - V Tp - V Tn/ I scmaxf / 9

E scr t r .V DD - V Tp - V Tn/ I scmaxr / 9

E scf E scr 81 when V DD V Tp J V Tn


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Lo"-Po"+r D+&ig, !, T+&'L+/r+ ( (*

S+or" Cr%)" C)rren"1 i sc.t /

Time (ns)0 1

I sc

Volt

V DD

i sc (t)

0

V i (t)V o(t)

V DD - V Tp

V Tn

t B t E

I scmaxf

*-"r$nss"or s"$r"s%ond)%"n'

n-"r$nss"or %)"s-off


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G!"%+ Po(er Dss*$"on G!"%+es $re "e,*or$r# %+$n'es n "+e 0$!)e of "+e o)"*)" Q )nne%ess$r#

"r$ns"ons

T+e# $re %$)sed d)e "o "+e s&e( n "+e n*)" s'n$!s "o $ '$"e G!"%+ *o(er dss*$"on $%%o)n"s for 7; Q 98 ; of "+e '!ob$! *o(er B$s% %on"rb)"es of +$$rds "o *o(er dss*$"on $re

◦ H$$rd 'ener$"on

◦ H$$rd *ro*$'$"on


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G!"%+ Po(er Dss*$"on

P 4 1;2 Vmin @

V,n : ,n 0o!"$'e s(n' $" "+e o)"*)" G!"%+ *o(er dss*$"on s de*enden" on

◦ O)"*)" !o$d

◦ In*)" *$""ern

◦

In*)" s!o*e

)$z$# ene$!ion %$n be red)%ed b# '$"e sn' $nd *$"+ b$!$n%n' "e%+n2)es

)$z$# pop$$!ion %$n be red)%ed b# )sn' !ess n),ber ofn0er"ers (+%+ "end "o $,*!f# $nd *ro*$'$"e '!"%+es


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S"$"% Po(er

S"$"% *o(er s %ons),ed e0en (+en %+* s 2)es%en"3

◦ R$"oed %r%)"s b)rn *o(er n f'+" be"(een ON "r$nss"ors

◦ Le$&$'e dr$(s *o(er fro, no,n$!!# OFF de0%es

8:

gs t ds

T T

V V V

nv v

ds ds I I e e

− −

= −

( )8t t ds s sb sV V V V η γ φ φ = − + + −

P I&!i V


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21

Le$&$'e Po(er Dss*$"on

Le$&$'e *o(er $s $ fr$%"on of "+e "o"$! *o(er n%re$ses $s %!o%& fre2)en%#dro*s3 T)rnn' s)**!# off n )n)sed *$r"s %$n s$0e *o(er3

For $ '$"e " s $ s,$!! fr$%"on of "+e "o"$! *o(er " %$n be s'nf%$n" for 0er#

!$r'e %r%)"s3 S%$!n' do(n fe$")res re2)res !o(ern' "+e "+res+o!d 0o!"$'e1 (+%+

n%re$ses !e$&$'e *o(er ro)'+!# do)b!es ("+ e$%+ s+rn&n'3

M)!"*!e-"+res+o!d de0%es $re )sed "o red)%e !e$&$'e *o(er .

I.&

4 6

CoB

=W;LV!

2 eBp=V+S

>VT)

VDS

;nV!

VDS dr$n "o so)r%e 0o!"$'e: $ *ro*or"on$!"# f$%"or

P = Pleakage v


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2(

Le$&$'e Po(er

I G

I

D

I.&

IPT

I+IDL

n n

V DD

R D$inSo&'e

+$!e

&/ Si =p

nMOS T$n.i.!o

+o&n#


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Lo"-Po"+r D+&ig, !, T+&'L+/r+ ( 22

Le$&$'e C)rren" Co,*onen"s S)b-"+res+o!d %ond)%"on1 I sb

Re0erse b$s *n )n%"on %ond)%"on1 I D G$"e nd)%ed dr$n !e$&$'e1 I !ID" d)e "o ")nne!n' $" "+e '$"e-dr$n o0er!$*

Dr$n so)r%e *)n%+ "+ro)'+1 I PT d)e "o s+or" %+$nne! $nd +'+ dr$n-so)r%e0o!"$'e

G$"e ")nne!n'1 I ! "+ro)'+ "+n o6de ,$# be%o,e s'nf%$n" ("+ s%$!n'3

I.& 4 6 CoB =W;L V!2 eBp=V+S >VT) ; nV! F

S&-!0e.0o# C&en!

8: %$rrer s)rf$%e ,ob!"#

Co6: '$"e o6de %$*$%"$n%e *er )n" $re$L: %+$nne! !en'"+W: '$"e (d"+V" &T2: "+er,$! 0o!"$'en: $ "e%+no!o'# *$r$,e"er


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Lo"-Po"+r D+&ig, !, T+&'L+/r+ ( 23

In%re$sed S)b-"+res+o!d Le$&$'e

0 V TH ’ V TH

" # g $ D r a i n c r r e n t )

!ate v#%tage

S%$!ed de0%e

I c

I sub


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THANYOU3

low power ppt unit-1

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