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TRANSCRIPT
Hig
h D
riv
e C
urr
en
t A
mp
lifi
ers
Bu
rak D
ün
da
r
50
40
92
20
4
Cu
rre
nt
Mo
de
An
alo
g
gC
ircu
it D
esig
n
Ov
erv
iew
Cla
ss
AB
Cu
rre
nt
Ou
tpu
tS
tag
es
C
lass A
B C
urr
en
t O
utp
ut S
tag
es
H
arm
on
ic D
isto
rtio
n D
ue
to
Ch
an
ne
l L
en
gth
Mo
du
latio
n
H
arm
on
ic D
isto
rtio
n D
ue
to
Mis
ma
tch
es
D
esig
n E
xa
mp
les
Cla
ss
AB
Ou
tpu
t S
tag
es
pg
C
urr
ent
mode
pow
er
am
plif
iers
use
acurr
ent
outp
ut
C
urr
ent
mode p
ow
er
am
plif
iers
use a
curr
ent
outp
ut
sta
ge (
CO
S)
whic
h is a
ble
to d
rive a
gro
unded load.
C
OS
isth
em
ostcriticalblo
ck
for
imple
menting
a
CO
S is the m
ost critical blo
ck f
or
imp
lem
en
tin
g a
hig
h d
rive c
urr
ent
am
plif
ier.
In
brief
acurr
ent
am
plif
ier
ism
ade
up
ofa
In
brief
a c
urr
ent
am
plif
ier
is m
ade u
p o
f a
transre
sis
tance a
mplif
ier
low
input
resis
tance
and
hig
h g
ain
and a
cla
ss A
B C
OS
whic
h h
as t
o p
rovid
e
hig
h d
rive c
apabili
ty a
nd h
igh o
utp
ut
resis
tance.
Cla
ss A
B O
utp
ut
Sta
ges –
Gen
era
l C
urr
en
t A
mp
lifi
er
Str
uctu
rep
Cla
ss A
B O
utp
ut
Sta
ges –
No
nid
ealiti
es
A
CO
Shas
two
main
sourc
es
ofnon
-id
ea
lity
wh
ich
ca
use
A
CO
S h
as tw
o m
ain
so
urc
es o
f non
ide
alit
y w
hic
h c
au
se
de
via
tio
n f
rom
, th
e id
ea
l D
C t
ran
sfe
r ch
ara
cte
ristic a
nd
aff
ect
line
arity
Th
ech
an
ne
l-le
ng
thm
od
ula
tio
ne
rro
ro
fth
em
irro
rin
gtr
an
sis
tor
–T
he
ch
an
ne
l-le
ng
th m
od
ula
tio
n e
rro
r o
f th
e m
irro
rin
g tra
nsis
tor
(MA
2 M
B2 in F
ig. 1);
–T
he m
ism
atc
hes b
etw
een the tra
nsis
tors
in the c
urr
ent m
irro
r.
C
hannel-
len
gth
mo
du
latio
nis
ca
use
db
yd
iffe
ren
ce
sin
the
C
hannel-
len
gth
modula
tion
is c
au
se
d b
y d
iffe
ren
ce
s in t
he
dra
in-s
ourc
e v
oltage o
f th
e tra
nsis
tors
. It
ca
n b
e r
ed
uce
d b
y
incre
asin
g t
heir c
hannel le
ngth
, how
ever,
this
means larg
er
chip
are
aand
wors
efr
equency
response
ch
ip a
rea
and w
ors
e f
req
ue
ncy r
esp
on
se
.
M
ism
atc
h e
rro
rs a
ffe
ct a
ny to
po
log
y a
nd
ca
n o
nly
be
elim
ina
ted
w
ith
a c
are
ful la
yo
ut.
Cla
ss A
B O
utp
ut
Sta
ges –
Co
nfi
gu
rati
on
sg
C
OS
based
on
regula
rcascaded
C
OS
based o
n r
egula
r cascaded
mirro
rs.
T
he
circuit
exhib
its
hig
houtp
ut
T
he c
ircuit e
xhib
its h
igh o
utp
ut
resis
tance a
nd s
win
g,
but
any s
trate
gy
allo
win
g t
he d
rain
volta
ge t
o tra
ck the
gg
gate
voltage in t
he o
utp
ut
transis
tors
(MA
2 a
nd M
B2)
is lackin
g.
Channel
lth
dl
titill
liit
liit
length
modula
tio
n s
till
limits lin
earity
.
Cla
ss A
B O
utp
ut
Sta
ges –
Co
nfi
gu
rati
on
sg
A
firs
tso
lutio
nw
hic
hre
du
ce
sA
first
so
lutio
n w
hic
h r
ed
uce
s
ch
an
ne
l-le
ng
th m
od
ula
tio
n is
usin
g th
e c
asco
de
d m
irro
r w
ith
dyn
am
ic m
atc
hin
g
sh
ow
nin
Fig
2It
exh
ibits
ash
ow
n in
Fig
. 2
. It e
xh
ibits a
red
uce
d n
on
-lin
ea
rity
by a
fa
cto
r of
2 thanks to t
he
follo
win
g a
ctio
n o
f co
mm
on
d
rain
MA
4(M
B4
)d
rain
MA
4 (
MB
4).
A
be
tte
r so
lutio
n fo
r re
du
cin
g
ha
rmo
nic
dis
tort
ion
du
e to
ch
an
ne
l le
ng
th m
od
ula
tio
n is
ach
iee
db
imp
lem
en
tin
ga
ch
ieve
d b
y im
ple
me
ntin
g
the
CO
S u
sin
g a
cu
rre
nt
mirro
r w
ith
im
pro
ve
d d
yn
am
ic
ma
tch
ing
as in
Fig
. 3
.
Cla
ss A
B O
utp
ut
Sta
ges –
Co
nfi
gu
rati
on
sg
F
inalC
OS
ism
ade
up
oftw
o
Fin
al C
OS
is m
ade u
p o
f tw
o
co
mp
lem
en
tary
active
-ga
in e
nh
an
ce
d
mirro
rs w
hic
h b
ase t
heir p
erf
orm
ance
on
a p
rincip
le q
uite s
imila
r to
the g
ain
-b
tit
hi
Th
tt
boosting techniq
ue. T
he t
wo c
urr
en
t m
irro
rs a
re c
om
po
se
d o
f tr
an
sis
tors
M
A1-M
A3 a
nd M
B1–M
B3 a
nd t
wo
au
xili
ary
vo
lta
ge
am
plif
iers
,A
la
nd
A2
.a
uxili
ary
vo
lta
ge
am
plif
iers
, A
l and A
2.
Th
an
ks to
th
ese
, th
e d
rain
vo
lta
ge
s o
f M
A1, M
A2 a
nd M
B1, M
B2 a
re a
lmost
eq
ua
l e
ve
n f
or
larg
e c
urr
en
ts.T
hu
s,
a
CO
Sith
hig
hlin
earit
perf
orm
ance
isC
OS
with h
igh
lin
earity
perf
orm
ance
is
achie
ved.
The u
se o
f A
1 a
nd A
2 a
lso
pro
vid
es a
very
hig
h o
utp
ut re
sis
tance.
Harm
on
ic D
isto
rtio
n D
ue t
o C
han
nel
Len
gth
Mo
du
lati
on
–R
eg
ula
r C
as
co
de
d C
OS
Ha
rmo
nic
dis
tort
ion
du
eto
ch
an
ne
lle
ng
th
Ha
rmo
nic
dis
tort
ion
du
e t
o c
ha
nn
el le
ng
th
mo
du
latio
n is o
bta
ine
d f
or
reg
ula
r ca
sco
de
d
cu
rre
ntm
irro
ra
ssu
min
ga
lltr
an
sis
tors
are
cu
rre
nt m
irro
r a
ssu
min
g a
ll tr
an
sis
tors
are
ma
tch
ed
.IM
=>
Ma
gn
itu
de
ofS
inu
so
ida
lIM
=>
Ma
gn
itu
de
of S
inu
so
ida
l
Input C
urr
ent
I Q=
> Q
uie
sce
nt C
urr
en
t
Harm
on
ic D
isto
rtio
n D
ue t
o C
han
nel
Len
gth
Mo
du
lati
on
–R
eg
ula
r C
as
co
de
d C
OS
A
se
xp
ecte
dfr
om
cu
rre
ntm
irro
rsw
ith
ide
ally
ma
tch
ed
A
s e
xp
ecte
d fro
m c
urr
en
t m
irro
rs w
ith ideally
matc
hed
tr
an
sis
tors
an
d e
qu
al tr
an
sco
nd
ucta
nce
ga
in,
the
eve
n-o
rde
r h
arm
on
ic d
isto
rtio
n is v
ery
lo
w.
In fa
ct,
it is
pro
po
rtio
na
l to
th
e
diffe
rence
betw
een
the
two
channel-
length
modula
tion
diffe
ren
ce b
etw
een
th
e tw
o c
hannel
length
modula
tion
para
mete
rs. T
here
fore
, th
ird-o
rder
harm
onic
dis
tort
ion b
ecom
es
the d
om
inant
contr
ibution.
H
arm
onic
dis
tort
ions
HD
2and
HD
3are
dependent
upon
the
H
arm
onic
dis
tort
ion
s H
D2 a
nd H
D3 a
re d
ependent
upon
th
e
rela
tive m
agnitude o
f th
e input sig
nal and
pand
n. T
hey c
an
be r
educed b
y incre
asin
g t
he tra
nsconducta
nce g
ain
and/o
r th
e
ch
an
ne
lle
ng
thofth
etr
an
sis
tors
.channel le
ngth
of th
e tra
nsis
tors
.
F
or
dynam
ic m
atc
hin
g t
ype c
ascoded C
OS
, H
D2 a
nd H
D3
term
s a
re r
educed b
y a
facto
r of 2
Harm
on
ic D
isto
rtio
n D
ue t
o C
han
nel
Len
gth
Mo
du
lati
on
–C
asco
ded
CO
S
wit
h Im
pro
ved
Dyn
am
ic M
atc
hin
gp
yg
H
D2
ispro
port
ionalto
the
channel
len
gth
mo
du
latio
n
HD
2 is
pro
port
ional to
the c
hannel-
len
gth
modula
tion
coeffic
ients
and t
o the d
iffe
rences b
etw
een V
TN
and
VTP.
VTP.
T
he im
pro
ved d
ynam
ic m
atc
hin
g m
akes t
hird o
rder
harm
onic
dis
tort
ion
term
alm
ost
neglig
ible
.harm
onic
dis
tort
ion
term
alm
ost
ne
glig
ible
.
Harm
on
ic D
isto
rtio
n D
ue t
o C
han
nel
Len
gth
Mo
du
lati
on
-G
ain
Bo
oste
d
Ca
sc
od
ed
CO
S
H
D2
and
HD
3depend
on
the
diffe
rence
and
the
sum
H
D2 a
nd H
D3 d
ep
en
d o
n t
he d
iffe
rence a
nd t
he s
um
of p
and
nre
spectively
. H
ow
ever
the topolo
gy
pro
vid
es
avery
low
-dis
tort
ion
CO
Sbecause
HD
2pro
vid
es a
very
low
dis
tort
ion
CO
S b
ecause H
D2
and H
D3
are
gre
atly r
educed b
y the a
mplif
ier
gain
.
IM=
> M
ag
nitu
de
of
Sin
uso
ida
l
Input C
urr
ent
IQ=
> Q
uie
sce
nt C
urr
en
t
A =
> A
mp
lifie
r G
ain
Harm
on
ic D
isto
rtio
n D
ue t
o C
han
nel
Le
ng
th M
od
ula
tio
n-
Sim
ula
tio
n R
esu
lts
g
Ha
rmo
nic
Dis
tort
ion
Du
e t
o M
ism
atc
he
s-
Th
resh
old
Vo
lta
ge
Mis
ma
tch
es
g
N
egle
cting
the
channel
length
modula
tion
and
any
N
eg
lectin
g t
he c
hannel-
len
gth
mo
du
latio
n a
nd a
ny
oth
er
sourc
e o
f non-lin
earity
, except
that
caused b
y
mis
matc
hes
inVT,second
and
third
ord
er
harm
onic
mis
matc
hes in V
T,second
and t
hird o
rder
harm
onic
dis
tort
ion f
orm
ula
s c
an b
e o
bta
ined.
IM=
> M
ag
nitu
de
of
Sin
uso
ida
l In
pu
t C
urr
en
t
I=
>Q
uie
sce
ntC
urr
en
tIQ
=>
Qu
iesce
nt C
urr
en
t
Ha
rmo
nic
Dis
tort
ion
Du
e t
o M
ism
atc
he
s-
Tra
ns
co
nd
uc
tan
ce
Mis
ma
tch
es
A
se
co
nd
mis
ma
tch
err
or
wh
ich
giv
es
rise
toh
arm
on
ic
A s
eco
nd
mis
ma
tch e
rror
whic
h g
ive
s r
ise t
o h
arm
onic
dis
tort
ion is the m
ism
atc
h o
f th
e tra
nsco
nd
ucta
nce
ga
in o
f th
e
mirro
rin
g tra
nsis
tors
.
T
he s
econd-o
rder
harm
onic
dis
tort
ion is independent
of th
e
sig
nal am
plit
ude a
nd is p
roport
ional to
the d
iffe
rence b
etw
een
the
re
lative
tra
nsco
nd
ucta
nce
mis
ma
tch
es. T
he
th
ird
-ord
er
ha
rmo
nic
dis
tort
ion
is a
bo
ut
eq
ua
l to
ze
ro.
De
sig
n E
xa
mp
les
gp
In
this
section
we
will
dis
cuss
som
eim
ple
menta
tions
In
this
section w
e w
ill d
iscuss s
om
e im
ple
me
nta
tio
ns
ofcurr
ent
am
plif
iers
based o
n t
he o
utp
ut
sta
ge in
Fig
.6,w
hic
hpro
ved
tobe
the
best
solu
tion
for
Fig
. 6, w
hic
h p
roved
to b
e t
he b
est
solu
tion
for
min
imiz
ing h
arm
onic
dis
tort
ion d
ue t
o c
hannel-le
ngth
modula
tion.
A V
FC
OA
(V
olt
ag
e F
eed
back C
urr
en
tO
pera
tio
nalA
mp
lifi
er)
-S
ch
em
ati
cp
p)
A V
FC
OA
(V
olt
ag
e F
eed
back C
urr
en
tO
pera
tio
nalA
mp
lifi
er)
-S
tru
ctu
rep
p)
T
he
tra
nsre
sis
tan
ce
am
plif
ier
isco
mp
ose
do
ftr
an
sis
tors
M1-
T
he t
ran
sre
sis
tan
ce a
mplif
ier
is c
om
posed
of tr
an
sis
tors
M1
M1
2 a
nd
inclu
de
s,
as m
ain
blo
cks, a
fo
lde
d c
asco
de
am
plif
ier.
a
co
mm
on
so
urc
ea
mp
lifie
r a
nd
a c
lass A
B v
olta
ge
fo
llow
er.
T
he
fold
ed
caseodc
am
plif
ier
ism
ade
up
oftr
ansis
tors
M3
-M6.
The f
old
ed
ca
se
od
c a
mplif
ier
ism
ade u
p o
f tr
an
sis
tors
M3
M6.
The c
om
mon s
ourc
e a
mplif
ier
is m
ade u
p o
ftr
ansis
tor
M8 a
nd
cu
rre
nt g
en
era
tor
IB6
. It
is c
on
ne
cte
d to
th
e first sta
ge
by
the
com
mon-d
rain
M7 w
hic
h p
rovid
es a
pro
pe
r le
ve
l sh
ift.
Th
e
pp
pcom
mon
sourc
e a
mplif
ier
drives the c
lass A
B v
oltage follo
wer
whic
h is c
om
posed o
ftr
ansis
tors
M9-M
12. D
iode-c
onnecte
d
tra
nsis
tors
M9
an
d M
10
accu
rate
ly s
et th
e c
urr
ent in
M11
and
yM
12 to a
multip
le o
f IB
6.
A V
FC
OA
(V
olt
ag
e F
ee
db
ac
k C
urr
en
tO
pe
rati
on
alA
mp
lifi
er)
-D
es
ign
Eq
ua
tio
ns
pp
)g
q
D
Ctr
an
sre
sis
tan
ce
D
C t
ran
sre
sis
tan
ce
In
put and o
utp
ut re
sis
tances
T
ran
sfe
r fu
nctio
n
G
ain
ba
nd
wid
th p
rod
uct
A V
FC
OA
(V
olt
ag
e F
eed
back C
urr
en
tO
pera
tio
nalA
mp
lifi
er)
-P
erf
orm
an
ce
pp
)
A C
OA
(C
urr
en
t O
pera
tio
nal A
mp
lifi
er)
-
Sch
em
ati
c
A C
OA
(C
urr
en
t O
pera
tio
nal A
mp
lifi
er)
-
Str
uctu
re
T
he
circu
itco
nta
ins
thre
em
ain
blo
cks:a
tra
nsre
sis
tan
ce
am
plif
ier
a
Th
e c
ircu
it c
on
tain
s th
ree
ma
in b
locks: a
tra
nsre
sis
tan
ce
am
plif
ier,
a
tra
nsco
nd
ucta
nce
am
plif
ier
an
d a
CO
S.
T
he
tra
nsre
sis
tan
ce
am
plif
ier
is m
ad
e u
p o
f tr
an
sis
tors
M1
-M7
an
d is
ba
se
d o
n a
fo
lde
d c
asco
de
am
plif
ier.
It
makes the m
ain
contr
ibution to
pth
e o
pe
n-lo
op
ga
in o
f th
e o
ve
rall
am
plif
ier.
In
ad
ditio
n, co
mm
on
dra
in
M7 p
rovid
es the p
roper
bia
s v
oltage to the follo
win
g s
tage.
T
he
. tr
an
sco
nd
ucta
nce
am
plif
ier
is c
om
po
se
d o
f tr
an
sis
tors
M8
-M1
9d
ki
lA
Bf
hi
Ittit
tl
da
nd
wo
rks in
cla
ss A
B f
ash
ion. It c
on
stitu
tes a
cro
ss-c
ou
ple
d
diffe
ren
tia
l sta
ge
.
F
req
ue
ncy c
om
pe
nsa
tio
n o
f th
e m
ain
am
plif
ier
is a
ch
ieve
d b
y M
ille
r ca
pa
cita
nce
Cc
an
dn
ulli
ng
resis
tor
Rc
ca
pa
cita
nce
Cc
an
d n
ulli
ng
re
sis
tor
Rc.
T
his
circu
it c
an
ea
sily
be
co
nve
rte
d to
fu
lly d
iffe
ren
tia
l ve
rsio
n b
y
sim
ply
ad
din
g a
re
plic
a o
f th
e in
pu
t sta
ge
(h
ere
bia
se
d a
t V
B)
A C
OA
(C
urr
en
t O
pera
tio
nal A
mp
lifi
er)
–
Desig
n E
qu
ati
on
sg
q
T
ran
sco
nd
ucta
nce
ga
in
Tra
nsco
nd
ucta
nce
gain
T
ota
l tr
an
sco
nd
ucta
nce
ga
in
T
ran
sfe
rfu
nctio
n
Tra
nsfe
r fu
nctio
n
G
ain
bandw
idth
pro
du
ct
p
A C
OA
(C
urr
en
t O
pera
tio
nal A
mp
lifi
er)
–
Perf
orm
an
ce
Use o
f F
ully D
iffe
ren
tial C
OA
as
Cu
rren
t am
plifi
er
p
Use o
f F
ully D
iffe
ren
tial C
OA
as
Tra
nsco
nd
ucta
nce a
mp
lifi
er
p
Use o
f F
ully D
iffe
ren
tial C
OA
as
Vo
ltag
e a
mp
lifi
er
gp
Use o
f F
ully D
iffe
ren
tial C
OA
as
Tra
nsre
sis
tan
ce a
mp
lifi
er
p
Re
fere
nc
es
GP
alm
isa
no
GP
alu
mb
oS
Pe
nn
isi
G
. P
alm
isa
no
, G
. P
alu
mb
o,
S. P
en
nis
i,
CM
OS
cu
rre
nt a
mp
lifie
rs, K
luw
er
Aca
de
mic
Pu
blis
he
rs1
99
9P
ub
lish
ers
, 1
99
9 Th
an
k y
ou