2. single stage opamps - cnmpserra/uab/damics/damics-2-single.pdf2. single stage opamps design of...
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![Page 1: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/1.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
1/74Mono Differential CMFB Folded Cascode Gain
2. Single Stage OpAmps
Francesc Serra Graells
[email protected] de Microelectrònica i Sistemes Electrònics
Universitat Autònoma de Barcelona
[email protected] Circuits and Systems
IMB-CNM(CSIC)
![Page 2: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/2.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
2/74Mono Differential CMFB Folded Cascode Gain
The Mono-Transistor Amplifier1
Differential Topologies2
Common Mode Feedback3
Folded Amplifiers4
Cascode Topologies5
Gain Enhancement Techniques6
![Page 3: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/3.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
3/74Mono Differential CMFB Folded Cascode Gain
The Mono-Transistor Amplifier1
Differential Topologies2
Common Mode Feedback3
Folded Amplifiers4
Cascode Topologies5
Gain Enhancement Techniques6
![Page 4: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/4.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
4/74Mono Differential CMFB Folded Cascode Gain
Single-Transistor Topologies
Operational voltage amplifier (OpAmp)?
Commonsource
Commongate
Backgate
Supposing forward saturation,drain is selected as output portdue to its high impedance (CLM):
Current-driven bias pointto control circuit power
![Page 5: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/5.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
5/74Mono Differential CMFB Folded Cascode Gain
Single-Transistor Topologies
Operational voltage amplifier (OpAmp)?
High input impedance
Commonsource
Commongate
Backgate
Inverting amplifier
Supposing forward saturation,drain is selected as output portdue to its high impedance (CLM):
Current-driven bias pointto control circuit power
Highest Gm/IDLow input impedance
Non-inverting amplifier Inverting amplifier
Low input impedance
Lowest Gm/IDModerate Gm/ID
Powerefficiency
Easierfeedback
Latchupp+ n+ n+
Triple-well required
![Page 6: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/6.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
6/74Mono Differential CMFB Folded Cascode Gain
Voltage Transfer Curve
Large signal analysis of common source amplifier:
M1M1 operating instrong inversion andforward saturation:
VB=0 unless specified
M1 in conductionM1 in saturation
CLM negligiblein large signal
M1
e.g. autobiasing
![Page 7: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/7.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
7/74Mono Differential CMFB Folded Cascode Gain
Gain and Frequency ResponseCommon source small signal analysis:
M1 strong inversionand forward saturation
bias point
M1
G
D
BS
G
D
BS
Incremental equivalent circuit:
![Page 8: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/8.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
8/74Mono Differential CMFB Folded Cascode Gain
Gain and Frequency Response
M1 strong inversionand forward saturation
bias point
M1
Incremental equivalent circuit: DC voltage gain
inputtransconductance
outputresistance
3dB/oct
In general, for CMOS amplifiers:
3dB/oct
6dB/oct
![Page 9: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/9.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
9/74Mono Differential CMFB Folded Cascode Gain
Gain and Frequency Response
M1 strong inversionand forward saturation
bias point
M1
Incremental equivalent circuit: Spectral bandwidth
0.5oct/oct
Frequency
-20dB/dec
open-loop
max. closed-loop(i.e. follower)
closed-loop
0.5oct/oct
![Page 10: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/10.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
10/74Mono Differential CMFB Folded Cascode Gain
Dynamic Range
Uncorrelated phenomena and low-frequency:
Noise equivalent circuit:
Thermal noise contribution only(f > flicker corner):
Time
x10 (20dB)
x1 (0dB)
Equivalent input noise:
![Page 11: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/11.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
11/74Mono Differential CMFB Folded Cascode Gain
Dynamic RangeNoise equivalent circuit:
1.5dB/oct
3dB/oct
Thermal noise contribution only(f > flicker corner):
Time
x10 (20dB)
x1 (0dB)
DynamicRange
PowerSupply
TemperatureBandwidth
![Page 12: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/12.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
12/74Mono Differential CMFB Folded Cascode Gain
Full CMOS Circuit
All operating in strong inversion andforward saturation bias points:
M1
Similar performance analysis: Large signal VTC:
M2M3
M1 in conductionM1 in saturation
M2 in saturationM2 in conduction
![Page 13: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/13.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
13/74Mono Differential CMFB Folded Cascode Gain
Full CMOS Circuit
M1
Similar performance analysis: Small signal gain and bandwidth:
M2M3
3dB/oct
3dB/oct
6dB/oct
All operating in strong inversion andforward saturation bias points: 0.5oct/oct
0.5oct/oct
![Page 14: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/14.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
14/74Mono Differential CMFB Folded Cascode Gain
The Mono-Transistor Amplifier1
Differential Topologies2
Common Mode Feedback3
Folded Amplifiers4
Cascode Topologies5
Gain Enhancement Techniques6
![Page 15: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/15.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
15/74Mono Differential CMFB Folded Cascode Gain
Single-ended OpAmps:
Power railsresistive parasitics
M1Digital
Capacitive/inductivecoupling parasitics
Dynamic sources of interference:
Power supply currents
Large signals (e.g. digital states)
EM fieldsTemperature gradients
Mechanical stress
Compact area and power
Poor signal integrity
Fully-Differential vs Single-Ended
![Page 16: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/16.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
16/74Mono Differential CMFB Folded Cascode Gain
Pseudo-differential OpAmps:
M1Digital
Interference rejection
Area and power overheads (x2)
M2
Signal true info
Signal baseline only
Fully-Differential vs Single-Ended
![Page 17: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/17.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
17/74Mono Differential CMFB Folded Cascode Gain
Pseudo-differential OpAmps:
M1Digital
M2
Signal true info
Signal baseline only
Interference rejection
Area and power overheads (x2)
Full-scale extension (+6dB)
Noise increase (+3dB)
Time
SNR(+3dB)
Fully-Differential vs Single-Ended
![Page 18: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/18.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
18/74Mono Differential CMFB Folded Cascode Gain
Pseudo-differential OpAmps:
M1Digital
M2
Signal true info
Signal baseline only
Interference rejection
Area and power overheads (x2)
Full-scale extension (+6dB)
Noise increase (+3dB)
Time
SNR(+3dB)
Distortion cancellation (even harm.)
Limited by device matching
Fully-Differential vs Single-Ended
![Page 19: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/19.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
19/74Mono Differential CMFB Folded Cascode Gain
Basic CMOS topology:
devicemultiplicity
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
sameaspectratio
Fully-Differential OpAmps
![Page 20: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/20.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
20/74Mono Differential CMFB Folded Cascode Gain
devicemultiplicity
Differential input only:
M1
M6
M2
M4M3
M5
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
sameaspectratio
??
Basic CMOS topology:
Fully-Differential OpAmps
![Page 21: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/21.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
21/74Mono Differential CMFB Folded Cascode Gain
devicemultiplicity
Mostly used for single-ended signaling
M5-6 current mirror asymmetry
M1
M6
M2
M4M3
M5
Not full cancellation of unwanted terms
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
sameaspectratio
Differential input only:Basic CMOS topology:
Fully-Differential OpAmps
![Page 22: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/22.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
22/74Mono Differential CMFB Folded Cascode Gain
Large signal VTC:
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
M2 in conductionM2 in saturation
M7 in saturationM7 in conduction
All operating in strong inversionsaturation + neglecting CLM
Basic CMOS topology:
Fully-Differential OpAmps
![Page 23: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/23.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
23/74Mono Differential CMFB Folded Cascode Gain
Large signal VTC:
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
M2 in conductionM2 in saturation
M1 in saturationM1 in conduction
Reduced output range
Basic CMOS topology:
Fully-Differential OpAmps All operating in strong inversionsaturation + neglecting CLM
![Page 24: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/24.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
24/74Mono Differential CMFB Folded Cascode Gain
Large signal VTC:
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
Reduced output range
Basic CMOS topology:
Fully-Differential OpAmps All operating in strong inversionsaturation + neglecting CLM
![Page 25: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/25.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
25/74Mono Differential CMFB Folded Cascode Gain
Large signal VTC:
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
Reduced output range
Basic CMOS topology:
Fully-Differential OpAmps All operating in strong inversionsaturation + neglecting CLM
![Page 26: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/26.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
26/74Mono Differential CMFB Folded Cascode Gain
Large signal VTC:
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
Reduced output range
More offset contributions
Threshold voltagemismatching only
Prob.
Pelgrom's Law
Basic CMOS topology:
Fully-Differential OpAmps All operating in strong inversionsaturation + neglecting CLM
![Page 27: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/27.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
27/74Mono Differential CMFB Folded Cascode Gain
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
Basic CMOS topology:
Fully-Differential OpAmps
Small signal differential and common DC gains:
![Page 28: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/28.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
28/74Mono Differential CMFB Folded Cascode Gain
Small signal differential and common DC gains:
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
Basic CMOS topology:
Fully-Differential OpAmps
common outputdifferential output
differential input common input
![Page 29: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/29.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
29/74Mono Differential CMFB Folded Cascode Gain
Small signal differential and common DC gains:
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
Basic CMOS topology:
Fully-Differential OpAmps
Perfect matching (M1=M2 and M6=M7):
differential output
differential input
![Page 30: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/30.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
30/74Mono Differential CMFB Folded Cascode Gain
Small signal differential and common DC gains:
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
Basic CMOS topology:
Fully-Differential OpAmps
Perfect matching (M1=M2 and M6=M7):
Real matching (e.g. VTH1=VTH2):
Neglectingcommon output
![Page 31: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/31.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
31/74Mono Differential CMFB Folded Cascode Gain
Reduced output range
Summary of design guidelines:
Matching is critical
Basic CMOS topology:
Fully-Differential OpAmps
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
performanceresources
![Page 32: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/32.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
32/74Mono Differential CMFB Folded Cascode Gain
The Mono-Transistor Amplifier1
Differential Topologies2
Common Mode Feedback3
Folded Amplifiers4
Cascode Topologies5
Gain Enhancement Techniques6
![Page 33: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/33.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
33/74Mono Differential CMFB Folded Cascode Gain
Single-ended differential OpAmps:
e.g. max.feedback
Well-defined and stablecommon-mode level
Common-Mode Output Issue
Fully-differential OpAmps:
Specific auxiliary controlcircuitry is needed in practice...
M1
M6
M2
M4M3
M5
M1
M6
M2
M7M5
M4M3 High sensitivity totechnology mismatching(M5-M6|7 and M3-M4)!
![Page 34: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/34.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
34/74Mono Differential CMFB Folded Cascode Gain
Common-mode feedback (CMFB) loop:
CMFB control functionality:
Computing error according to reference level
Sensing common-mode output
Applying needed common-mode correction
Common-Mode Output Issue
Behaviorallyequivalent...
M1 M2 M1 M2
Multi-stage OpAmps require oneCMFB loops for each stage
gain accuracyCMFBcontroldesign?
bandwidth stability
Not to be confused with CMRR!
![Page 35: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/35.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
35/74Mono Differential CMFB Folded Cascode Gain
Resistive-based sensing:
Continuous-Time CMFB
Passive common-modeoutput estimation
M1
M5
M2
M6M4
M3
R1 R2
![Page 36: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/36.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
36/74Mono Differential CMFB Folded Cascode Gain
Resistive-based sensing:
Continuous-Time CMFB
Passive common-modeoutput estimation
M1
M5
M2
M6M4
M3
R1 R2
OpAmp original OR is preserved
Resistive extra loading... ...or limitedCMFB bandwidth
![Page 37: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/37.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
37/74Mono Differential CMFB Folded Cascode Gain
Resistive-based sensing:
Continuous-Time CMFB
M1
M5
M2
M6M4
M3
Resistive loading is avoidedOR severe reduction
M7
Common-mode output level is technology dependent!
M8
R1R2
Power consumption overhead
![Page 38: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/38.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
38/74Mono Differential CMFB Folded Cascode Gain
Resistive-based sensing:
Continuous-Time CMFB
M1
M5
M2
M6M4
M3
Resistive loading is avoidedOR severe reduction
M7
Common-mode output level is technology dependent!
M8
R1R2
Power consumption overhead
M9
Master-slaveautomatic tuning
![Page 39: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/39.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
39/74Mono Differential CMFB Folded Cascode Gain
Resistive-based sensing:
Continuous-Time CMFB
Compact circuit solutionStrong OR reductionNo power consumption overhead
Low-pass CMFBfiltering
M1
M6
M2
M5
M4M3
C1
1 2:
R1 R2
Common-mode outputdefined by technology
![Page 40: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/40.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
40/74Mono Differential CMFB Folded Cascode Gain
MOS-based sensing:
Continuous-Time CMFB
M1
M9
M2
M10M8
M5M6M7
M4x1
M3x2
Supposing M5, M6 and M7working in deep conduction:
Master-slavetuning
By CMFB symmetry (M5=M6):
By bias symmetry (M5|6=M7 and M3=M4):
![Page 41: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/41.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
41/74Mono Differential CMFB Folded Cascode Gain
MOS-based sensing:
Continuous-Time CMFB
M1
M9
M2
M10M8
Resistive loading is avoided
Gain non-linearity
M5M6M7
M4x1
M3x2
No power consumption overhead
Supposing M5, M6 and M7working in deep conduction:
Negligible OR reductionMaster-slave
tuning
Technology compensation
By CMFB symmetry (M5=M6):
By bias symmetry (M5|6=M7 and M3=M4):
![Page 42: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/42.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
42/74Mono Differential CMFB Folded Cascode Gain
Switched-capacitor (SC) implementation:
Discrete-Time CMFB
e.g. fully-differential integrator stage
C2P
C1P
C2N
C1N
clock
![Page 43: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/43.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
43/74Mono Differential CMFB Folded Cascode Gain
Switched-capacitor (SC) implementation:
Discrete-Time CMFB
Low loop-gain
e.g. fully-differential integrator stage
Reduced power overheads
C2P
C1P
C2N
C1N
clock
Capacitive CMFB sensing
M1
M6
M2
M7M5
M4M3CFP CFN
![Page 44: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/44.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
44/74Mono Differential CMFB Folded Cascode Gain
The Mono-Transistor Amplifier1
Differential Topologies2
Common Mode Feedback3
Folded Amplifiers4
Cascode Topologies5
Gain Enhancement Techniques6
![Page 45: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/45.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
45/74Mono Differential CMFB Folded Cascode Gain
Basic fully-differential topology (not showing CMFB):
M1
M6
M2
M7M5
M4M3
111
1 2:
: :
Output Range Issue
Time
OR improvement requiresvery large aspect ratios!
Not compatible with otheroptimization rules (e.g. CMRR)
![Page 46: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/46.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
46/74Mono Differential CMFB Folded Cascode Gain
Fully-differential folded OpAmp (not showing CMFB):
M1
M6
M2
M5
M9M7
1 2:
Folded Topologies
M10
M4 M3
M8
11 :11 :
1:1 :
??
![Page 47: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/47.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
47/74Mono Differential CMFB Folded Cascode Gain
Fully-differential folded OpAmp (not showing CMFB):
M1
M6
M2
M5
M9M7
1 2:
Folded Topologies
Static power consumption (x2)
M10
M4 M3
M8
11 :11 :
1:1 :
All operating in strong inversionsaturation + neglecting CLM
low-impedancenodes
Device silicon area (x2)
Still a singlestage Opamp!
![Page 48: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/48.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
48/74Mono Differential CMFB Folded Cascode Gain
Fully-differential folded OpAmp (not showing CMFB):
M1
M6
M2
M5
M9M7
1 2:
Folded Topologies
Static power consumption (x2)
M10
M4 M3
M8
11 :11 :
1:1 :
All operating in strong inversionsaturation + neglecting CLM
low-impedancenodes
Device silicon area (x2)
Still a singlestage Opamp!
Full-scale OR optimization
![Page 49: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/49.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
49/74Mono Differential CMFB Folded Cascode Gain
Fully-differential folded OpAmp (not showing CMFB):
M1
M6
M2
M5
M9M7
1 2:
Folded Topologies
Static power consumption (x2)
M10
M4 M3
M8
11 :11 :
1:1 :
All operating in strong inversionsaturation + neglecting CLM
Device silicon area (x2)
Full-scale OR optimization
High supply voltage needed...
![Page 50: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/50.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
50/74Mono Differential CMFB Folded Cascode Gain
Fully-differential dual folded OpAmp (not showing CMFB):
Folded Topologies
Static power consumption (x3)
Device silicon area (x3)
M1 M2
M13M12
2
M9 M3
M5
2:21 :
1 :
M11
M6
1 :
M4M10
M7 M8
: 1
![Page 51: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/51.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
51/74Mono Differential CMFB Folded Cascode Gain
Fully-differential dual folded OpAmp (not showing CMFB):
Folded Topologies
Static power consumption (x3)
All operating in strong inversionsaturation + neglecting CLM
Device silicon area (x3)
Same OR optimization
M1 M2
M13M12
2
M9 M3
M5
2:21 :
1 :
low-impedancenodes
Still a single stage Opamp!
M11
M6
1 :
M4M10
M7 M8
: 1
Compatible with low supply voltage
Suposing:
![Page 52: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/52.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
52/74Mono Differential CMFB Folded Cascode Gain
Folded Topologies
M1
M6
M2
M5
M9M7
1 2:
M10
M4 M3
M8
11 :11 :
1:1 :
M1
M6
M2
M5
M8M7
1
2M10
M4 M3
11 :11 :
1:
1 :M9
Single-ended foldedOpAmp counterparts:
![Page 53: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/53.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
53/74Mono Differential CMFB Folded Cascode Gain
Single-ended foldedOpAmp counterparts:
Folded Topologies
M1 M2
M13M12
2
M9 M3
M5
2:21 :
1 :
M11
M6
1 :
M4M10
M7 M8
: 1
M1 M2
M13M12
2
M3
M5
2:2
1 :
M11
M6
1 :
M4
M10
M7 M8
1
M9
1 :
![Page 54: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/54.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
54/74Mono Differential CMFB Folded Cascode Gain
The Mono-Transistor Amplifier1
Differential Topologies2
Common Mode Feedback3
Folded Amplifiers4
Cascode Topologies5
Gain Enhancement Techniques6
![Page 55: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/55.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
55/74Mono Differential CMFB Folded Cascode Gain
Principle BasisCMOS OpAmp general linear model:
inputtransconductance
outputresistance
Enhancement by increasingMOSFET output impedance?
![Page 56: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/56.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
56/74Mono Differential CMFB Folded Cascode Gain
Principle BasisCMOS OpAmp general linear model:
inputtransconductance
outputresistance
Frequency
-20dB/dec
Enhancement by increasingMOSFET output impedance?
Gain improvement:
No speed enhancement (GBW)
Lower equivalent input noise
Accurate feedback functions
![Page 57: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/57.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
57/74Mono Differential CMFB Folded Cascode Gain
Principle of Operation
Output impedance multiplier:
mydevice
cascodedevice
Introducing cascoding in OpAmps:
M1 transconductordevice
M2 cascodedevice
Aplicable to most analog basicbuilding blocks (e.g. current mirror,voltage differential pair) M1
M2
voltageattenuation
DC voltagebiasing level
![Page 58: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/58.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
58/74Mono Differential CMFB Folded Cascode Gain
Basic Cascode OpAmp
M1
M2
Low-frequency small-signal analysis: CMOS OpAmp model:
![Page 59: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/59.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
59/74Mono Differential CMFB Folded Cascode Gain
Basic Cascode OpAmp
M1
M2
Low-frequency small-signal analysis: CMOS OpAmp model:
![Page 60: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/60.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
60/74Mono Differential CMFB Folded Cascode Gain
Basic Cascode OpAmp
M1
M2
Low-frequency small-signal analysis: CMOS OpAmp model:
output impedanceof cascode device
similartransconductance
voltagegain factor!
output impedanceof transconductor device
voltagegain factor!
seriescombination
higheroutput impedance
![Page 61: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/61.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
61/74Mono Differential CMFB Folded Cascode Gain
Regulated Cascode OpAmp
M1
M2
even largerattenuation factors!
??
![Page 62: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/62.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
62/74Mono Differential CMFB Folded Cascode Gain
Regulated Cascode OpAmp
M1
M2
Low-frequency small-signal analysis: CMOS OpAmp model:
even largerattenuation factors!
![Page 63: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/63.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
63/74Mono Differential CMFB Folded Cascode Gain
Regulated Cascode OpAmp
M1
M2
Low-frequency small-signal analysis: CMOS OpAmp model:
even largerattenuation factors!
Minimalist implementation:
M1
M2M3
![Page 64: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/64.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
64/74Mono Differential CMFB Folded Cascode Gain
Output Range Optimization
Basic cascode DC biasing:
supposing M2=M4:
M1
M2
M3
M4
Regulated cascode DC biasing:
alternative low-voltage approach:
M1
M2M3
M1
M2
M3
M4
All operating in strong inversionsaturation + neglecting CLM
operating in stronginversion conduction
![Page 65: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/65.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
65/74Mono Differential CMFB Folded Cascode Gain
Practical Cascode OpAmps
Fully differential + folded + cascode topology example:
M1
M5
M2
M4M3
M9M8M7M6
M16M15M14
M13M12M11M10
optimizedDC biasing
low-impedancenodes
dualcascodingrequired!
cascoding notneeded here...
![Page 66: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/66.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
66/74Mono Differential CMFB Folded Cascode Gain
The Mono-Transistor Amplifier1
Differential Topologies2
Common Mode Feedback3
Folded Amplifiers4
Cascode Topologies5
Gain Enhancement Techniques6
![Page 67: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/67.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
67/74Mono Differential CMFB Folded Cascode Gain
Principle BasisCMOS OpAmp general linear model:
inputtransconductance
outputresistance
Enhancement by increasingMOSFET input transconductance?
![Page 68: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/68.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
68/74Mono Differential CMFB Folded Cascode Gain
Principle BasisCMOS OpAmp general linear model:
inputtransconductance
outputresistance
Frequency
-20dB/dec
Gain improvement:
Lower equivalent input noise
Accurate feedback functionsEnhancement by increasingMOSFET input transconductance?
Speed enhancement (GBW)
![Page 69: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/69.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
69/74Mono Differential CMFB Folded Cascode Gain
Partial Positive Feedback
Basic differential transconductor:
M1 M2
![Page 70: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/70.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
70/74Mono Differential CMFB Folded Cascode Gain
Partial Positive Feedback
Basic differential transconductor: Introducing local positive feedback:
M1
M6
M2
M5M4 M3
11 :11 :
low-impedancenodes
still a singlestage transconductor...
M7 M8
1/N 1/N: :
M1 M2
cross-coupleddevices
Cross-coupled pair
Folded structure
Partial feedback design by sizing ratio
keeping same large signal
range
![Page 71: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/71.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
71/74Mono Differential CMFB Folded Cascode Gain
Partial Positive Feedback
Small signal transconductance:
M1
M6
M2
M5M4 M3
11 :11 :
M7 M8
1/N 1/N: :
![Page 72: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/72.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
72/74Mono Differential CMFB Folded Cascode Gain
Partial Positive Feedback
Small signal transconductance:
M1
M6
M2
M5M4 M3
11 :11 :
M7 M8
1/N 1/N: :
Half-circuit analysis:
Infinite tail sink resistance
Perfect symmetry (no mismatching)
Purely differential input
common-mode = virtual ground
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2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
73/74Mono Differential CMFB Folded Cascode Gain
Partial Positive Feedback
Small signal transconductance:
M1
M6
M2
M5M4 M3
11 :11 :
M7 M8
1/N 1/N: :
Half-circuit analysis:
Infinite tail sink resistance
Perfect symmetry (no mismatching)
Purely differential input
![Page 74: 2. Single Stage OpAmps - CNMpserra/uab/damics/damics-2-single.pdf2. Single Stage OpAmps Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells Mono Differential](https://reader033.vdocuments.net/reader033/viewer/2022060822/609ab2253cdc020f301ce3bc/html5/thumbnails/74.jpg)
2. Single Stage OpAmps
Design of Analog and Mixed Integrated Circuits and Systems F. Serra Graells
74/74Mono Differential CMFB Folded Cascode Gain
Practical Gain Enhanced OpAmp
Single-ended + folded + cross-coupled example:
M1
M6
M2
M5M4 M3 M7 M8
M10M9
Prone to instability
Larger gain and GBW
Compatible withfolding and cascoding
It can generate hysteresis
Local positive feedback vs global negative feedback: