EE 359 Electronic Circuits March 3, 2005 0 Multistage Amplifiers Two Stage CMOS OpAMP Bipolar OpAmp...
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Transcript of EE 359 Electronic Circuits March 3, 2005 0 Multistage Amplifiers Two Stage CMOS OpAMP Bipolar OpAmp...
March 3, 20051
EE 359 Electronic Circuits
Multistage AmplifiersMultistage Amplifiers
Two Stage CMOS OpAMP
Bipolar OpAmp
SPICE
March 3, 20052
EE 359 Electronic Circuits
HW #5
• 7.10, 7.21, 7.71, 7.88
Due Tuesday
March 3, 20053
EE 359 Electronic Circuits
Why Multistage?
• Practical transistor amplifiers consist of a number of stages connected in cascade.
• First stage typically high input impedance, & CMMR
• Middle stages amplification
• Last stage, low output impedance
March 3, 20054
EE 359 Electronic Circuits
Two stage CMOS
Q8,Q5:current mirrors
March 3, 20055
EE 359 Electronic Circuits
Differential Input
013
313 ||||
1
2rr
g
vgv O
m
idmg
Usually the leakage resistances are much larger than 1/g_m3
3
13 2 m
midg g
gvv
March 3, 20056
EE 359 Electronic Circuits
Differential Gain
March 3, 20057
EE 359 Electronic Circuits
Differential Input
22
2
23
41
234
idm
id
m
mmo
idmgmo
vg
v
g
ggi
vgvgi
March 3, 20058
EE 359 Electronic Circuits
• vG2=0, vG1=vid
2/2
1
||
0
04020
omd
momid
d
ArgA
rrgRGv
vA
March 3, 20059
EE 359 Electronic Circuits
Equivalent Circuit MOSFET Opamp
March 3, 200510
EE 359 Electronic Circuits
Bias Circuit for Opamp
• Bias current independent of Supply Voltage and MOSFET threshold volage
• Q_12, Q_13 deliberately mismatched, Q_12 4x wider
March 3, 200511
EE 359 Electronic Circuits
Bipolar Opamp
March 3, 200512
EE 359 Electronic CircuitsBipolar Opamp
March 3, 200513
EE 359 Electronic Circuits
Small Signal Analysis
• Input and output Impedances
March 3, 200514
EE 359 Electronic Circuits
Gain of Second Stage
March 3, 200515
EE 359 Electronic Circuits
Last stage
March 3, 200516
EE 359 Electronic Circuits
Small Signal Model
March 3, 200517
EE 359 Electronic CircuitsFrequency Response
March 3, 200518
EE 359 Electronic Circuits Spice Simulation
March 3, 200519
EE 359 Electronic Circuits
Opamp Transfer Function
March 3, 200520
EE 359 Electronic Circuits
Differential Gain
March 3, 200521
EE 359 Electronic Circuits
Frequency Response• Adjust frequency resonse by adding resistor in Q4
March 3, 200522
EE 359 Electronic Circuits
Common Mode Rejection Ratio