Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15 1 Polytech’Montpellier – MEA4 M2 EEA – Systèmes Microélectroniques Analog IC Design One- and two-transistors Amplifiers Pascal Nouet – 2015/2016 - [email protected]http://www.lirmm.fr/~nouet/homepage/lecture_ressources.html Introduction • Analog Integrated Circuits are based on elementary stages – Voltage references – Current mirrors – Current sources – Amplifier stages V out T 1 V in V dd R V out T 1 V in V dd I bias T 3 T 2 I bias V out T 1 V in V dd
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Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
• Analog Integrated Circuits are based on elementary stages – Voltage references – Current mirrors – Current sources – Amplifier stages
Vout T1
Vin
Vdd
R
Vout T1
Vin
Vdd
Ibias
T3 T2 Ibias
Vout T1
Vin
Vdd
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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Outline
• Elementary amplifiers – Common source amplifier
• Biasing with a resistor • Biasing with an ideal current source • Biasing with a current miror
– Common gate amplifier – Common drain or source follower – Overview of Basic CMOS Amplifiers
• Common mode issues – Differential pair and differential amplifier – Differential output amplifier
• Homework & Labs
• Resistance biasing: dimensionnement & plage de fonctionnement – Vout > Veff – Vin(dc) à Veff1 à W/L (Ibias) – R à Vout # Vdd/2
• Small-Signal Model – Voltage Gain, input and output resistance
Common Source amplifier
Vout T1
Vin
Vdd
R
gm1.vin rds//R vin vout
g1 d1
s1
tneffindcin VVvVV +≅+=
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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R-biased Common Source amplifier
-16,7 V/V
Vin (V)
Ids (A)
Vout (V)
Common Source amplifier
• Biasing with an ideal current source
• Biasing point – Vin > Vtn ; Vin-Vtn = Veff < Vout ; Vout # Vdd/2 – à W/L
• Small-Signal Model – Voltage Gain, input and output resistance
Ibias
Vout T1
Vin
Vdd
gm1.vin rds vin vout
g1 d1
s1
Impact of a resistive load ?
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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I-biased Common Source amplifier
.INCLUDE ../modn.mod M1 d g s b MODN w=25u l=1.6u M=4 vs s 0 0 vb b 0 0 vg g 0 0 Iload vdd d 100u Valim vdd 0 5 .dc vg 0.98 1 0.002 .op .probe v(d) Id=par('i(Valim)') .option probe post=2 .end
Common Source amplifier
• Biasing by current mirror
• Biasing point – Vin > Vtn ; Vin-Vtn = Veff < Vout ; Vout#Vdd/2 – à W/L
• Small-Signal Model – Voltage Gain, input and output resistance
gm.vin rdsn // rdsp
vin vout
g1 d1
s1 Vout
T1
Vin
Vdd
Ibias
T3 T2
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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T-biased Common Source amplifier
.INCLUDE ../modn.mod
.Include ../modp.mod M1 d g s b MODN w=25u l=1.6u M=4 M2 d g1 vdd vdd MODP w=25u l=1.6u M=4 M3 g1 g1 vdd vdd MODP w=25u l=1.6u M=4 vs s 0 0 vb b 0 0 vg g 0 0 Ibias g1 0 100u Valim vdd 0 5 .dc vg 0.96 1.02 0.002 .probe v(d) Id=par('i(Valim)') .option probe post=2 .end
Impact of a capacitive load ?
Outline
• Elementary amplifiers – Common source amplifier – Common gate amplifier – Common drain or source follower – Overview of Basic CMOS Amplifiers
• Common mode issues – Differential pair and differential amplifier – Differential output amplifier
• Homework & Labs
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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Common gate amplifier
All transistors are saturated
( ) 0112
1
=⋅−−⋅+⋅
−=
inminoutdsoutds
ings
vgvvgvg
vv
21
11
dsds
dsm
in
outv gg
ggvvA
++
==
Vdd
Ibias
T3 T2
T1 Vbias
Vout
Vin gm1.vgs1 rds1
rds2
vgs1 vout
vin
( ) ( ) inmdsoutdsds vggvgg ⋅+=⋅+ 1121
Input resistance ? 1
2 2
mv
dsin gA
rr ≅=
Common gate amplifier
Vdd
Ibias
T3 T2
T1 Vbias Vout
Vin
Impact of a resistive load ?
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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Common gate amplifier
Amplificateur grille commune M2 vdd g out vdd MODP w=25u l=1.6u M=4 M3 g g vdd vdd MODP w=25u l=1.6u M=4 M1 in bias out in MODN w=25u l=1.6u M=4 Ibias g 0 100u Vbias bias 0 1 Valim vdd 0 dc 5 Vin in 0 dc 0 Rl out 0 100k .dc vin 0 .1 0.001
Vdd
Ibias
T3 T2
T1 Vbias Vout
Vin
Outline
• Elementary amplifiers – Common source amplifier – Common gate amplifier – Common drain or source follower – Overview of Basic CMOS Amplifiers
• Common mode issues – Differential pair and differential amplifier – Differential output amplifier
• Homework & Labs
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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Source follower (Common drain)
Vout
Ibias
T3 T2
T1 Vin
Vdd
gm2.vgs2 rds2 vgs2=0
gm1.vgs1 rds1 vgs1
vout
vin
( ) 1121
1
// gsmdsdsout
outings
vgrrv
vvv
⋅×=
−=
1121
1 ≅++
==mdsds
m
in
outv ggg
gvv
A
Output resistance? 1121
11
mmdsdsout ggggr ≅
++=
All transistors are saturated
Source follower (Common drain)
Vout
Ibias
T3 T2
T1 Vin
Vdd
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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Outline
• Elementary amplifiers – Common source amplifier – Common gate amplifier – Common drain or source follower – Overview of Basic CMOS Amplifiers
• Common mode issues – Differential pair and differential amplifier – Differential output amplifier
• Homework & Labs
Overview of Basic CMOS Amplifiers
Vin
Vdd
T2
Rp
T1
T3 Vout
�
T1
Vdd
T2
Rp T3
Vout
Vin
�
T1
Vdd
T2
Rp T3
Vout
Vbias
Vin �
Vin
Vdd
T2
Rp
T1
T3 Vout
�
Vbias
Vdd
T2
Rp
T1
T3 Vout
Vin
�
T1
Vdd
T2
Rp T3
Vout
Vin
�
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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Outline
• Elementary amplifiers – Common source amplifier – Common gate amplifier – Common drain or source follower – Overview of Basic CMOS Amplifiers
• Common mode issues – Differential pair and differential amplifier – Differential output amplifier
• Homework & Labs
Common Source Amplifier Limitations
• Biasing – Vin=Veff+Vtn
Current Mirror Biasing
Vdd
T1 Vout
Vin
( )( )21
1211 //
dsds
mdsdsmV gg
grrgA+
−=−=
∞=inr 21 // dsdsout rrr =
T3 T2
Vdd
21 dd II =
1
2
Vout
Vin↗
Vdd
3
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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Differential Input Stage: small-signal output voltage
2in
mvg1dsr
2in
mvg−
3
1
mg 42 // dsds rr44 gsm vg
4gsv
outv
( )4244 //2 dsdsin
mgsmout rrvgvgv ×⎟⎠
⎞⎜⎝
⎛ +=
34
12 m
inmgs gvgv ×≈
( )423
4 //22 dsdsin
min
mm
mout rrvgvg
ggv ×⎟⎟
⎠
⎞⎜⎜⎝
⎛+=
43 mm gg =
( )42 // dsdsmin
out rrgvv
×=
2in
mcinvVV +=+
2in
mcinvVV −=−
Differential Input Stage: small-signal gain analysis
Vdd
T1
Vout
Vin+
T4 T3
Vdd
T2
Vin-
Id1 Id2
Ibias
( )42
2,1422,1 //
dsds
mdsdsm
in
out
ggg
rrgvv
+=×=
22
2,1
biasp
biasn
mv II
gA
λλ +=
2,12,12,1
22
eff
bias
eff
bias
m VI
V
I
g =⎟⎠
⎞⎜⎝
⎛
=
( ) 2,1
2
effpnv VA
λλ +=
2,1
2,12,1
2WL
CµI
Voxn
deff =
2,12,1)(2
LW
I
CµA
dpn
oxnv
⋅+=
λλ
Low Veff and large length for large gain
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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Differential Input Stage: common-mode input range (CMIR)
Vdd
T1 Vmc
T4 T3
Vdd
T2 Vmc
Id1 Id2
Ibias A
B
All transistors must operate in saturation:
min,AA VV >
tpeffddB VVVV −−= 4,3
2,1effAB VVV >−4,3efftp VV +
min,AV>(for correct operation of the current source)
( ) min,2,1 AefftnmcA VVVVV >+−=
2,1min, efftnAmc VVVV ++>2,1effV>
AeffBeffAB VVVVVV +>→>− 2,12,1
( ) AtnAmcB VVVVV +−−>
tnmcB VVV −>
tnBmc VVV +<tntpeffddmc VVVVV +−−< 4,3
Low Veff for large CMIR
Outline
• Elementary amplifiers – Common source amplifier – Common gate amplifier – Common drain or source follower – Overview of Basic CMOS Amplifiers
• Common mode issues – Differential pair and differential amplifier – Differential output amplifier
• Homework & Labs
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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Homework & Lab
T5
Ibias 10.Ibias
Vdd=3.3V
VA
T7 T6
R
Ibias
T3 T2
T4 T1
T9
T8
Ibias
VC
T71 T61
VB
T81
V-
V+
T11 T12
T14 T13
10.Ibias
T2bis
T1bis
VS
T15 Cf Rs
VD
VS1
Dimensionnement de l’étage différentiel
1°) Calculez le W/L de T13 et T14 de façon à ce que la tension de sortie soit égale à 2,5V lorsque V1=V2=1,6V. Estimez ensuite la résistance de sortie de cet étage.
2°) Calculez le W/L de T11 et T12 de façon à ce que le gain différentiel soit de 500.
3°) Quelle serait la fréquence de coupure de cet étage si on connecte une capacité de 5 pF à la sortie à la place du 2ème étage de gain ?
Homework & Lab
T5
Ibias 10.Ibias
Vdd=3.3V
VA
T7 T6
R
Ibias
T3 T2
T4 T1
T9
T8
Ibias
VC
T71 T61
VB
T81
V-
V+
T11 T12
T14 T13
10.Ibias
T2bis
T1bis
VS
T15 Cf Rs
VD
VS1
Dimensionnement du 2ème étage de gain
1°) Calculez la résistance de sortie de l’étage puis le W/L du transistor T15 ainsi que le gain petit-signal de l’étage Av.
2°) On connecte une résistance de 100kΩ en sortie de l’amplificateur. Calculez le nouveau gain de l’étage A’
v ?
Analog IC Design - Academic year 2015/2016 - Session 4 06/12/15
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Homework & Lab
Performances statiques de l’OTA Miller
Déterminez les valeurs théoriques du gain statique (petit-signal) de l’amplificateur (en l’absence de charge), de la plage de mode commun d’entrée admissible et de la dynamique de sortie.
Caractérisation statique de l’OTA Miller
Tracez la caractéristique statique VS=f(V+-V-) sans charge de sortie pour un mode commun égal à Vdd/2. Relevez le point de pente maximum (V+-V-)max de cette caractéristique et déduisez-en le gain expérimental.
Caractérisation dynamique de l’OTA Miller
Tracez le diagramme de Bode du montage et concluez sur la stabilité de ce montage utilisé en suiveur de tension.
Montez l’amplificateur en suiveur de tension puis appliquez un échelon de tension entre 1V et 2V sur l’entrée et observez la sortie. Conclure et expliquez les résultats obtenus.