chap2 1 - the university of new mexicoece-research.unm.edu/jimp/vlsi/slides/chap2_1.pdf · gs)...
TRANSCRIPT
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
1(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
MO
S T
rans
isto
r D
efini
tion
sn-
type
MO
S: M
ajor
ity
carr
iers
are
ele
ctro
ns.
p-ty
pe M
OS:
Maj
orit
y ca
rrie
rs a
re h
oles
.
Posi
tive
/neg
ativ
e vo
ltag
e ap
plie
d to
the
gate
(wit
h re
spec
t to
subs
trat
e)en
hanc
es th
e nu
mbe
r of
ele
ctro
ns/h
oles
in th
e ch
anne
l and
incr
ease
s co
n-du
ctiv
ity
betw
een
sour
ce a
nd d
rain
.
Vt d
efine
s th
e vo
ltag
e at
whi
ch a
MO
S tr
ansi
stor
beg
ins
to c
ondu
ct. F
or v
olt-
ages
less
than
Vt (
thre
shol
d vo
ltag
e), t
he c
hann
el is
cut
off
.
gate
-to-
sour
ce v
olta
ge (V
gs)
Dra
in
(Ids
)C
urre
nt
Vtn
0
n-ch
anne
l enh
ance
men
t MO
S
-Vtp
Dra
in
(Ids
)C
urre
nt
p-ch
anne
l enh
ance
men
t MO
S
gate
-to-
sour
ce v
olta
ge (V
gs)
Ass
ume
sour
ce-t
o-dr
ain
volt
age
(Vds
) is
fixed
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
2(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
MO
S T
rans
isto
r D
efini
tion
sIn
nor
mal
ope
rati
on, a
pos
itiv
e vo
ltag
e ap
plie
d be
twee
n so
urce
and
dra
in(V
ds).
No
curr
ent fl
ows
betw
een
sour
ce a
nd d
rain
(Ids
= 0
) wit
h V
gs =
0 b
ecau
se o
f
back
to b
ack
pn ju
ncti
ons.
For
n-M
OS,
wit
h V
gs >
Vtn
, ele
ctri
c fie
ld a
ttra
cts
elec
tron
s cr
eati
ng c
hann
el.
Cha
nnel
is p
-typ
e si
licon
whi
ch is
inve
rted
to n
-typ
e by
the
elec
tron
sat
trac
ted
by th
e el
ectr
ic fi
eld.
Sou
rce
Dra
inG
ateV
gsV
ds
Gat
e O
xide
n+n+
p-su
bstr
ate
n-ch
anne
l
GN
DD
rain
Sou
rce
I ds
I ds
GN
D
n-M
OS
tran
sist
or
Pol
y
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
3(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
n-M
OS
Enh
ance
men
t T
rans
isto
r P
hysi
csT
hree
mod
es b
ased
on
the
mag
nitu
de o
f Vgs
: acc
umul
atio
n, d
eple
tion
and
inve
rsio
n.
Sou
rce
Dra
in
Gat
e
Vgs
= 0
GN
D
GN
D
Acc
umul
atio
n M
ode
Pol
y
-+
Vd
s =
0-+
n-M
OS
tra
nsis
tor
++
++
++
++
++
++
++
++
++
++
++
--
--
--
++
++
++
++
++
++
++
++
++
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
4(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
n-M
OS
Enh
ance
men
t T
rans
isto
r P
hysi
cs
Sou
rce
Dra
in
Gat
e
Vgs
> 0
an
d V
gs<
= V
t
GN
D
GN
D
Dep
leti
on M
ode
Pol
y
-+
Vd
s =
0-+
n-M
OS
tran
sist
or
depl
etio
n re
gion
++
++
++
++
++
++
++
++
--
--
--
++
++
++
++
++
++
++
++
Sou
rce
Dra
in
Gat
e
Vgs
> V
t
GN
D
GN
D
Inve
rsio
n M
ode
Pol
y
-+
Vd
s =
0-+
n-M
OS
tran
sist
or
depl
etio
n re
gion
inve
rsio
n re
gion
++
++
++
++
--
--
--
--
--
--
--
--
++
++
++
++
++
++
++
++
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
5(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
n-M
OS
Enh
ance
men
t T
rans
isto
rW
ith
Vds
non
-zer
o, th
e ch
anne
l bec
omes
sm
alle
r cl
oser
to th
e dr
ain.
Whe
n V
ds <
= V
gs -
Vt (
e.g.
Vds
= 3
V, V
gs =
5V
and
Vt =
1V
), th
e ch
anne
l
reac
hes
the
drai
n (s
ince
Vgd
> V
t).
This
is te
rmed
line
ar,r
esis
tive
or
nons
atur
ated
reg
ion.
I ds i
s a
func
tion
of
both
Vgs
and
Vds
.
Sou
rce
Dra
in
Gat
e
Vgs
> V
t
GN
D
GN
D
Inve
rsio
n M
ode
Pol
y
-+
Vd
s >
0-+
n-M
OS
tran
sist
or
depl
etio
n re
gion
inve
rsio
n re
gion
p-su
bstr
ate
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
6(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
n-M
OS
Enh
ance
men
t T
rans
isto
rW
hen
Vds
> V
gs -
Vt (
e.g.
Vds
= 5
V, V
gs =
5V
and
Vt=
1V
), th
e ch
anne
l is
pinc
hed
off c
lose
to th
e dr
ain
(sin
ce V
gd <
Vt).
This
is te
rmed
sat
urat
ed r
egio
n. I d
s is
a fu
ncti
on o
f Vgs
, alm
ost i
ndep
ende
nt
of V
ds.
Sou
rce
Dra
in
Gat
e
Vgs
> V
t
GN
D
GN
D
Inve
rsio
n M
ode
Pol
y
-+
Vd
s >
0-+
n-M
OS
tran
sist
or
depl
etio
n re
gion
inve
rsio
n re
gion
p-su
bstr
ate
-
Vgs
- V
tV
ds
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
7(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
MO
S E
nhan
cem
ent
Tra
nsis
tor
MO
S tr
ansi
stor
s ca
n be
mod
eled
as
a vo
ltag
e co
ntro
lled
swit
ch. I
ds is
an
impo
rtan
t par
amet
er th
at d
eter
min
es th
e be
havi
or, e
.g.,
the
spee
d of
the
swit
ch.
Wha
t are
the
para
met
ers
that
eff
ect t
he m
agni
tude
of I
ds?
(Ass
ume
Vgs
and
Vds
are
fixe
d, e
.g. 5
V).
• Th
e di
stan
ce b
etw
een
sour
ce a
nd d
rain
(cha
nnel
leng
th).
• Th
e ch
anne
l wid
th.
• Th
e th
resh
old
volt
age.
• Th
e th
ickn
ess
of th
e ga
te o
xide
laye
r.•
The
diel
ectr
ic c
onst
ant o
f the
gat
e in
sula
tor.
• Th
e ca
rrie
r (e
lect
ron
or h
ole)
mob
ility
.
Sum
mar
y of
nor
mal
con
duct
ion
char
acte
rist
ics:
•C
ut-o
ff: a
ccum
ulat
ion,
I ds i
s es
sent
ially
zer
o.
•N
onsa
tura
ted:
wea
k in
vers
ion,
I ds d
epen
dent
on
both
Vgs
and
Vds
.
•Sa
tura
ted:
str
ong
inve
rsio
n, I d
s is
idea
lly in
depe
nden
t of V
ds.
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
8(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Thr
esho
ld V
olta
geV
t is
also
an
impo
rtan
t par
amet
er. W
hat e
ffec
ts it
s va
lue?
Mos
tare
rela
ted
toth
em
ater
ialp
rope
rtie
s.In
othe
rw
ords
,Vtis
larg
ely
dete
r-
min
ed a
t the
tim
e of
fabr
icat
ion,
rat
her
than
by
circ
uit c
ondi
tion
s, li
ke I d
s.
For
exam
ple,
mat
eria
l par
amet
ers
that
eff
ect V
t inc
lude
:
The
gat
e co
nduc
tor
mat
eria
l (po
ly v
s. m
etal
). T
he g
ate
insu
lati
on m
ater
ial (
SiO
2).
The
thic
knes
s of
the
gate
mat
eria
l. T
he c
hann
el d
opin
g co
ncen
trat
ion.
How
ever
, Vt i
s al
so d
epen
dent
on
Vsb
(the
vol
tage
bet
wee
n so
urce
and
sub
stra
te),
whi
ch is
nor
mal
ly 0
in d
ig-
ital
dev
ices
. T
empe
ratu
re: c
hang
es b
y -2
mV
/deg
ree
C fo
r lo
w s
ubst
rate
dop
ing
leve
ls.
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
9(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Thr
esho
ld V
olta
geTh
e ex
pres
sion
for
thre
shol
d vo
ltag
e is
giv
en a
s:
Vt
2φ b
2ε S
iqN
A2
φ bC
ox
--------
--------
--------
--------
-----
Vfb
++
=φ b
kT q------
NA
Ni
--------
ln=
whe
re
Idea
l thr
esho
ld v
olta
geFl
at b
and
volt
age
Bulk
pot
enti
alan
d NA
: Den
sity
of t
he c
arri
ers
in th
e do
ped
sem
icon
duct
or s
ubst
rate
.
Ni:
The
car
rier
con
cent
rati
on o
f int
rins
ic (u
ndop
ed) s
ilico
n.N
i1.
4510
×10
cm3–
at 3
00 d
egre
es K
()
=
k: B
oltz
man
’s c
onst
ant.
T: te
mpe
ratu
re. q
: ele
ctro
nic
char
ge.
kT q------
25m
V(a
t 300
deg
rees
K)
=
ε Si:
perm
itti
vity
of s
ilico
nε S
i1.
0612–
×10
Fara
ds/c
m=
Cox
: gat
e-ox
ide
capa
cita
nce.
Co
x
ε ox
t ox
--------
=
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
10(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Thr
esho
ld V
olta
geTh
resh
old
volt
age
(con
t.):
Typi
cal v
alue
s of
Vt f
or n
and
p-c
hann
el tr
ansi
stor
s ar
e +/
- 700
mV.
Vt
2φ b
2ε S
iqN
A2
φ bC
ox
--------
--------
--------
--------
-----
Vfb
++
= Idea
l thr
esho
ld v
olta
geFl
at b
and
volt
age
and V
fbφ m
s
Qfc
Co
x----
------
–=
whe
re Q
fc r
epre
sent
s th
e fix
ed c
harg
e du
e to
impe
rfec
tion
s in
silic
on-o
xide
inte
rfac
e an
d do
ping
.
and
φ ms
is w
ork
func
tion
diff
eren
ce b
etw
een
gate
mat
eria
l and
silic
on s
ubst
rate
(φga
te-φ
Si).
Typi
cal v
alue
s of
Vfb
for
n/p
tran
sist
or is
-0.9
V (w
ith
NA
= 1
016 c
m-3
)an
d-0
.2V
. (Se
e te
xt fo
r ex
ampl
es).
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
11(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Thr
esho
ld V
olta
geFr
om e
quat
ions
, thr
esho
ld v
olta
ge m
ay b
e va
ried
by
chan
ging
: T
he d
opin
g co
ncen
trat
ion
(NA
).
The
oxi
de c
apac
itan
ce (C
ox).
Sur
face
sta
te c
harg
e (Q
fc).
As
you
can
see,
it is
oft
en n
eces
sary
to a
djus
t Vt.
Two
met
hods
are
com
mon
: C
hang
e Q
fc b
y in
trod
ucin
g a
smal
l dop
ed r
egio
n at
the
oxid
e/su
bstr
ate
inte
rfac
e vi
a io
n im
plan
tati
on.
Cha
nge
Cox
by
usin
g a
diff
eren
t ins
ulat
ing
mat
eria
l for
the
gate
.
Ala
yer
ofSi
3N4
(sili
con
nitr
ide)
wit
ha
rela
tive
perm
itti
vity
of7.
5is
com
-
bine
d w
ith
a la
yer
of s
ilico
n di
oxid
e (r
elat
ive
perm
itti
vity
of 3
.9).
This
res
ults
in a
rel
ativ
e pe
rmit
tivi
ty o
f abo
ut 6
.
For
the
sam
e th
ickn
ess
diel
ectr
ic la
yer,
Cox
is la
rger
usi
ng th
e co
mbi
ned
mat
eria
l, w
hich
low
ers
Vt.
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
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ecem
ber
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000
6:10
pm
)U
MB
CU
M B
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UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Bod
y E
ffec
tIn
dig
ital
cir
cuit
s, th
e su
bstr
ate
is u
sual
ly h
eld
at z
ero.
The
sour
ces
of n
-cha
nnel
dev
ices
, for
exa
mpl
e, a
re a
lso
held
at z
ero,
exce
pt in
cas
es o
f ser
ies
conn
ecti
ons,
e.g
.,
The
sour
ce-t
o-su
bstr
ate
(Vsb
) may
incr
ease
at t
his
conn
ecti
ons,
e.g
. Vsb
N1
= 0
but V
sbN
2 /=
0.
Vsb
add
s to
the
chan
nel-
subs
trat
e po
tent
ial:
Vdd
AB O
ut
P1P2
N2
N1
Dra
in o
f N1
is s
ourc
e of
N2
Vt
2φ b
2ε S
iqN
A2
φ bV
sb+
Co
x----
--------
--------
--------
--------
--------
--------
-----V
fb+
+=
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
13(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Bas
ic D
C E
quat
ions
Idea
l firs
t ord
er e
quat
ion
for
cut-
off r
egio
n:
Idea
l firs
t ord
er e
quat
ion
for
linea
r re
gion
:
Idea
l firs
t ord
er e
quat
ion
for
satu
ratio
n re
gion
:
wit
h th
e fo
llow
ing
defin
itio
ns:
I ds
0=
Vg
sV
t≤
whe
n
I ds
βV
gs
Vt
–(
)Vd
s
Vd
s2 2
--------
--–
=w
hen
0V
<d
sV
gs
Vt
–<
I ds
βV
gs
Vt
–(
)2
2----
--------
--------
--------
--=
whe
n0
V<
gs
Vt
–V
ds
≤
βµε t o
x----
----W L----
-
=
µ=
surf
ace
mob
ility
of t
he c
arri
ers.
ε=
perm
itti
vity
of t
he g
ate
insu
lato
r.t o
x=
thic
knes
s of
the
gate
insu
lato
r.W
and
L a
re th
e w
idth
and
leng
th o
f cha
nnel
.
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
14(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Bas
ic D
C E
quat
ions
Proc
ess
depe
nden
t fac
tors
:.
Geo
met
ry d
epen
dent
fact
ors:
W a
nd L
.
Volt
age-
curr
ent c
hara
cter
isti
cs o
f the
n- a
nd p
-tra
nsis
tors
.
µCo
xC
ox
ε t ox
--------
=µε t o
x----
----or
whe
re
+ -+ -
1->5
V1-
>5V
Vds
(V)
Ids(mA)
VG
S =
1VV
GS
= 2V
Vds
= V
gs -
Vt
VG
S =
3V
VG
S =
4V
VG
S =
5V
1.0
2.0
3.0
4.0
5.0
12
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
15(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Bet
a ca
lcul
atio
nTr
ansi
stor
bet
a ca
lcul
atio
n ex
ampl
e:Ty
pica
l val
ues
for
an n
-tra
nsis
tor
in 1
mic
ron
tech
nolo
gy:
Com
pute
bet
a:
How
doe
s th
is b
eta
com
pare
wit
h p-
devi
ces:
n-tr
ansi
stor
gai
ns a
re a
ppro
xim
atel
y 2.
8 ti
mes
larg
er th
an p
-tra
nsis
tors
.
µ n50
0cm
2V
-sec
⁄=
ε3.
9ε 0
3.9
8.85
14–×1
0F/
cm (
perm
ittiv
ity o
f si
licon
dio
xide
)×
==
t ox
20nm
=
β n50
03.
98.
8514–
×10
××
0.2
5–×1
0----
--------
--------
--------
--------
--------
--------
------W L----
-86
.3W L----
- µA
V2
⁄=
=
βp
180
3.9
8.85
14–×1
0×
×
0.2
5–×1
0----
--------
--------
--------
--------
--------
--------
------W L----
-31
.1W L----
- µA
V2
⁄=
=
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
16(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Inve
rter
vol
tage
tra
nsis
tor
char
acte
rist
ics
Inve
rter
DC
cha
ract
eris
tics
Vou
t
Vin
A Vin
Vou
t
2.5VVD
D
2.5V
VD
D
AB
C
DE
A;n
-dev
ice
is c
ut o
ff (I
dsn=
0), p
-dev
ice
in li
near
.
B
0V
inV
tn≤
≤;n
-dev
ice
is in
sat
., p-
devi
ce in
line
ar.
Vtn
Vin
VD
D2⁄
∆–
<<
VD
D2⁄
∆–
Vin
VD
D2⁄
∆+
≤≤
;n-d
evic
e is
in s
at.,
p-de
vice
in s
at.
2.5V
1.6V3.6V
C DV
DD
2⁄∆
Vin
VD
DV
tp+
<<
+;n
-dev
ice
is in
line
ar, p
-dev
ice
in s
at.
VD
DV
tp+
Vin
VD
D≤
≤E
;n-d
evic
e is
in li
near
, p-d
evic
e in
cut
off
(Ids
p=0)
.
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
17(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Bet
a R
atio
sR
egio
n C
is th
e m
ost i
mpo
rtan
t reg
ion.
A s
mal
l cha
nge
in th
e in
put v
olta
ge,
Vin
, res
ults
in a
LA
RG
E ch
ange
in th
e ou
tput
vol
tage
, Vou
t.
This
beha
vior
desc
ribe
san
ampl
ifier
,the
inpu
tis
ampl
ified
atth
eou
tput
.The
ampl
ifica
tion
is te
rmed
tran
sist
or g
ain,
whi
ch is
giv
en b
y be
ta.
Both
the
n an
d p-
chan
nel t
rans
isto
rs h
ave
a be
ta. V
aryi
ng th
eir
rati
o w
illch
ange
the
char
acte
rist
ics
of th
e ou
tput
cur
ve.
Vou
t
Vin
2.5VVD
D
2.5V
VD
D
β nβ
p⁄
0.1
=
β nβ
p⁄
1.0
=
β nβ
p⁄
10=
Vou
tV
in
Bet
ara
tio o
f n a
ndp-
chan
nel t
rans
isto
rsva
ried
ove
r tw
o or
ders
of m
agni
tude
.
p n
As
ratio
is d
ecre
ased
, cur
ve s
hift
s to
the
righ
t, bu
t the
out
put t
rans
ition
rem
ains
sha
rp.
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
18(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Bet
a R
atio
sTh
eref
ore,
the
does
NO
T af
fect
sw
itch
ing
perf
orm
ance
.
Wha
t fac
tor
wou
ld a
rgue
for
a ra
tio
of 1
for
?
Load
cap
acit
ance
!
The
tim
e re
quir
ed to
cha
rge
or d
isch
arge
a c
apac
itiv
e lo
ad is
equ
al w
hen
.
Sinc
e be
ta is
dep
ende
nt W
and
L, w
e ca
n ad
just
the
rati
o by
cha
ngin
g th
esi
zes
of th
e tr
ansi
stor
cha
nnel
wid
ths,
by
mak
ing
p-ch
anne
l tra
nsis
tors
wid
er th
an n
-cha
nnel
tran
sist
ors.
β n βp
------
β n βp
------
β n βp
------
1=
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
19(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Noi
se M
argi
nsA
par
amet
er th
at d
eter
min
es th
e m
axim
umno
ise
volt
age
on th
e in
put o
f aga
te th
at a
llow
s th
e ou
tput
to r
emai
n st
able
.
Two
para
met
ers,
Low
noi
se m
argi
n (N
ML)
and
Hig
h no
ise
mar
gin
(NM
H).
NM
L=
diff
eren
cein
mag
nitu
debe
twee
nth
em
axLO
Wou
tput
volt
age
ofth
e
driv
ing
gate
and
max
LO
W in
put v
olta
ge r
ecog
nize
d by
the
driv
en g
ate.
VD
D
GN
D
Logi
cal h
igh
outp
ut ra
nge
Logi
cal l
owou
tput
rang
e
Logi
cal h
igh
inpu
t ran
ge
Logi
cal l
owin
put r
ange
inde
term
inat
ere
gion
VO
Hm
in
VO
Lmax
VIL
max
VIH
min
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
20(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Noi
se M
argi
nsId
eal c
hara
cter
isti
c: V
IH =
VIL
= (V
OH
+VO
L)/2
.
This
impl
ies
that
the
tran
sfer
char
acte
rist
icsh
ould
swit
chab
rupt
ly(h
igh
gain
in th
e tr
ansi
tion
reg
ion)
.
VIL
foun
d by
det
erm
inin
g un
ity
gain
poi
nt fr
om V
OH
.
Vou
t Vin
2.5VVD
D
2.5V
VD
D
β nβ
p⁄
1.0
>
Vou
tV
inp n
Uni
ty g
ain
poin
ts
VIH
= 3
.3
VIL
= 2
.3
Vtn
VD
D+V
tp
VO
H =
5V
VO
L =
0V
NM
L =
2.3V
NM
H =
1.7
V
Ass
ume
outp
utof
dri
ving
gat
eis
sta
ble
at s
uppl
yvo
ltage
, e.g
.,
Noi
se m
argi
ns a
re o
ften
com
prom
ised
to im
prov
e sp
eed.
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
21(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Pse
udo-
nMO
S In
vert
er
Ther
efor
e, th
e sh
ape
of th
e tr
ansf
er c
hara
cter
isti
c an
d th
e V
OL
of th
e in
vert
er
is a
ffec
ted
by th
e ra
tio
.
In g
ener
al, t
he lo
w n
oise
mar
gin
is c
onsi
dera
bly
wor
se th
an th
e hi
gh n
oise
mar
gin
for
Pseu
do-n
MO
S.
Pseu
do-n
MO
S w
as p
opul
ar fo
r hi
gh-s
peed
cir
cuit
s, s
tati
c R
OM
s an
d PL
As.
Vou
t
Vin
2.5V
VD
D
2.5V
VD
D
Vou
t
Vin
p n
p-de
vice
pul
l-up
(load
)
n-de
vice
pul
l-dow
n(d
rive
r)
Whe
n dr
iver
is o
n, s
tead
y-st
ate
curr
ent
flow
s - n
ot a
goo
d ch
oice
for l
ow-p
ower
Wp/
L p =
1/2
Wp/
L p =
2
Wp/
L p =
4
0Vci
rcui
ts.
β n βp
------
Prin
cipl
es o
f V
LSI
Des
ign
Det
ails
of
the
MO
S T
rans
isto
rC
MSC
491
B/7
11
22(D
ecem
ber
4, 2
000
6:10
pm
)U
MB
CU
M B
C
UNIVERSITY OF M
AR
YL
AN
D B
ALTIM
ORE COUNTY
1 9
6 6
Pse
udo-
nMO
SEx
ampl
e: C
alcu
lati
on o
f noi
se m
argi
ns:
The
tran
sfer
curv
efo
rth
eps
eudo
-nM
OS
inve
rter
can
beus
edto
calc
ulat
eth
eno
ise
mar
gins
of i
dent
ical
pse
udo-
nMO
S in
vert
ers.
Vou
t
Vin
VD
D
0.8V
VD
D
Vou
t
Vin
p n
Pseu
do-n
MO
S in
vert
er
5V 0.26
V
2.2V
VO
HV
IH
VO
LV
IL
NM
H =
VO
H -
VIH
= 5
V -
2.2V
= 2
.8V
NM
L =
VIL
- V
OL
= 0.
8V -
0.26
V =
0.5
4V (T
his
is q
uite
a b
it w
orse
than
NM
H)