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IIT-Bombay Lecture 6 M. Shojaei Baghini
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IIT-Bombay Lecture 6 M. Shojaei Baghini
Slides Figures
- Unless it’s mentioned figures and contents of
Basic Single Stage Amplifier Configurations Part I Ref.: Chapter 3 - - PowerPoint PPT Presentation
Basic Single Stage Amplifier Configurations Part I Ref.: Chapter 3 - - PowerPoint PPT Presentation
2 Basic Single Stage Amplifier Configurations Part I Ref.: Chapter 3 from Razavis book and chapter 3 from Grays book. IIT-Bombay Lecture 6 M. Shojaei
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IIT-Bombay Lecture 6 M. Shojaei Baghini
Common Source (CS) Amplifier with Resistive Load
Subthreshold/Moderate Inversion region
- Biasing using gate voltage
(DC or AC coupled) and drain resistor
- Concept of load line to trace large
signal values of voltage and current
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IIT-Bombay Lecture 6 M. Shojaei Baghini
CS Amplifier with Resistive Load (cont’d)
( ) ( )
− < −
− TH gs DS D DS
- x
D TH gs
- x
T nV V V D
V V V R V L W C R V V L W C nV e I R Gain
T TH gs
µ µ ) 3 ( ) 2 ( ) 1 ( :
Three different
- perating
regions:
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IIT-Bombay Lecture 6 M. Shojaei Baghini
CS Amplifier with Resistive Load (cont’d)
- Gain as a function of VDC across R
- Tradeoff between Av, BW, swing and power
- Tighter tradeoff as VDD scales down
( )
− = − =
− TH gs saturation D D D TH GS
- x
T ld subthresho D D T nV V V D
V V I R R V V L W C nV I R nV e I R Gain
T TH GS
_ _
2 : µ
Subthreshold region Saturation region
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IIT-Bombay Lecture 6 M. Shojaei Baghini
More relaxed tradeoff between Av and swing
( )(
)
1 1
2
M I TH gs v
V V A λ λ + − − ≈ CS Amplifier with Active Load Sources of nonlinearity:
- λ varies as VDS swings.
- “gm” varies as Vin varies.
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IIT-Bombay Lecture 6 M. Shojaei Baghini
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CS Amplifier with Diode-connected Load
( ) ( )
2 2 2 1 2 2 1
1 1
m b m b m m m v
g g L W L W g g g A + − = + − =
( ) ( )
2 1 2 1
L W L W g g A
p n m m v