Analog VLSI Circuits PPT-1

1. Learning Objectives:
LO1: To provide an overview of MOS characteristics and its importance in analog
design.
LO2: To introduce the design and analysis of active loaded amplifiers with and without
feedback.
LO3:To provide a practical approach for design of operational amplifiers.

2. Course Outcomes:
CO1: Ability to understand MOS characteristics and the design of current
sources.
CO2: Ability to apply techniques to design actively loaded amplifiers with
and without feedback.
CO3: Ability to design and analyze operational amplifiers, comparators
and oscillators.
CO4: Ability to evaluate amplifier characteristics from top-level
specifications using circuit simulators.

3. Skills Acquired: Provides a platform to design CMOS amplifiers with the help of
industry standard tools.

4. Unit 1: MOS Large-Signal and Small-Signal Equivalents, Biasing, High-Frequency Modeling, Short
Channel, Subthreshold Operation, Leakage Current, MOS Diodes, Active Resistors, Capacitors, Current
Sink and Source, Cascode Current Mirrors, Gain-Boosting, Current and Voltage References, Supply
Independent Biasing, Sensitivity.
Unit 2: MOS Inverters, Active Load, Current Source Load, Push-Pull Load, Small Signal Gain,
Frequency Response, Miller Effect-3-dB Frequency Determination, Single-Stage MOS Amplifiers,
Common Gate - Common Drain, Cascode, Differential Amplifiers, Active Loaded Differential Pair,
Feedback Amplifiers, Negative Feedback, Loop Gain, Oscillators, Comparators.
Unit 3: Two-Stage CMOS Op-Amp Design, Gain and Frequency Response, Stability and Compensation
in CMOS Op-Amps, Miller Compensated Op-Amp, Lead-Lag Compensation, Case Study of ADA4528: A
Zero Drift and Ultralow Noise Op-Amp
Course Contents

5. 1. B. Razavi, Design of Analog CMOS Integrated Circuits, Tata McGraw Hill, 2002, Reprint 2015.
2. P. E. Allen and D. R. Holberg, CMOS Analog Circuit Design, Third Edition, Oxford Press, 2011.
3. P. R. Gray, P. J. Hurst, S. H. Levis and R. G. Meyer, Analysis and Design of Analog Integrated
Circuits, Fifth Edition, Wiley Student Edition, 2009.
4. A S. Sedra, K. C. Smith and A. N. Chandorkar, Microelectronic Circuits -Theory and Applications,
Seventh Edition, Oxford University Press, 2017.
References

6. Assessment
Interna/
External
Maximum
Marks
Weightage
Quiz-1
Internal
10 7.5
Quiz-2 10 7.5
Mid-Term Examination 50 30
Quiz-3 10 7.5
Quiz-4 10 7.5
End Semester Examination External 100 40
Total 100
Evaluation Pattern: (60:40)

7. Analog VLSI design refers to the process of designing and fabricating ICs
that primarily involve analog electronic components and circuits on a
single semiconductor chip.
Analog circuits deal with continuous signals, such as voltages and
currents, as opposed to digital circuits that work with discrete values (0s
and 1s).
Analog VLSI Design

8. Analog VLSI design involves creating complex systems on a chip that
can perform various functions, such as amplification, filtering, signal
conditioning, voltage regulation, and more.
Some common examples of analog VLSI circuits include operational
amplifiers, voltage regulators, analog-to-digital converters (ADCs), digital-
to-analog converters (DACs), and radio-frequency (RF) circuits.
Analog VLSI Design
Digital VLSI is a more mature field than analog
VLSI. This is because digital circuits are easier
to design and fabricate. Digital circuits also have
a wider range of commercial applications.

9. Designing analog VLSI circuits can be challenging due to the inherent
complexities of dealing with real-world phenomena like noise, signal
distortion, temperature effects, and process variations.
Designers need a deep understanding of semiconductor physics, analog
circuit theory, device modeling, and fabrication processes.
Analog VLSI design plays a crucial role in various applications, including
communications, sensor interfaces, audio and video processing, medical
electronics, and more.
It requires a combination of creativity, engineering expertise, and a solid
foundation in analog electronics to successfully design and produce
functional analog VLSI circuits.
Analog VLSI Design

10. Analog VLSI is a more challenging field to design than digital VLSI. This is because analog circuits are
more sensitive to noise and power consumption. Analog circuits also require a more thorough
understanding of semiconductor physics and device modeling.
Analog vs. Digital VLSI Design

11. Voltage and Current Amplifier

12. Power Amplifier

13. Transformer: Voltage Amplifier

14. Transformer: Voltage Amplifier

15. Power: Passive Network
If ideal transformer is considered
If a passive network is considered
This will NOT guarantee either
voltage or current amplification

16. Maximum Power Delivered
If power and voltage
amplification is required,
then RL > 4RS

17. Maintain Constant Output Voltage
Maintain the output volage regardless of RL
Output voltage regulation

18. Variable Load Resistance
NOT possible by one
equation. Because resistance
RL is varying

19. Maintain Constant Output Voltage
Keping the output voltage (VO) same and
get the power amplification (Pout > Pin)
Voltage Regulation

20. Example: Variable RL
It does NOT satisfy
for a range of RL
It is for fixed value
of RL

21. Example: Loading of the Network by RL

22. Example: Loading of the Network by RL

23. Power Amplifier Requirement

24. Example: Loading of the Network by RL

25. Example: Loading of the Network by RL

26. Example: Range of Current for varying RL

27. Example: Controlling VO by adjusting R1

28. Negative Feedback
Instead of using fixed R use
variable R → R1
Resistive ratio will be
insensitive to changes in RL
This helps in analysing whether
a given network is able to drive
the connected load OR not.

29. Current and Voltage Sources
For an ideal voltage source if
the terminals are shorted,
the current ISC will be Ꝏ

30. Practical Current and Voltage Sources
Source resistance RS = 0.
This is practically NOT
possible
There exists a nonzero small
value of RS associated with
voltage source

31. Good voltage or current
source depends on the
relation between RS and RL
Consider RS = 100Ω
Current Source
Voltage Source
Practical Current and Voltage Sources

32. Motivations

33. Requirement of a bias voltage for power
amplification
Bias volage VDC

34. Requirement of additional supply for power
amplification

35. Superposition of Signals: Linear Systems
It describes how
signals interact
when they are
combined.

36. Superposition of Signals: Linear Systems
N
N

37. Power Amplification: LTI Systems

38. LTI Systems: Concept of Frequency Shift

39. Power Amplification: Non-Linear Systems

40. Consequence of Non - Linearity

41. Linearization of the Non-linear Element
Resistor (RL)
Non-Linear
Element
Relation between current
and voltage

42. Current and Voltage Relation
Voltage
Source
Non-Linear Element
I-V Relation

43. Variation in the input Vi
Current IN
Incremental
Current ∆IN
Change in Source Voltage

44. Linear Relationship Required
Taylor Series Applied
Non-Linear Device

45. Linear Relationship Established
Neglect the higher
order terms

46. Incremental Quantity Approximated
Relationship of
incremental quantities

47. Linear Relationship

48. Non-Linear Element: Final Remark

49. Incremental Current and Voltage Equivalents

50. Small Signal Model
Small Signal Model

51. Linearized Models of Common Electrical Elements

52. Common Electrical Elements

53. Example: Diode Equation
Apply KVL to the Circuit
Diode Equation
Quiescent point assumed to be 0.7V

54. Example: Small Signal
(Diode)
Incremental Voltage is 0.1V
Original Diode Circuit
Linearized
Circuit
Diode equation

55. Example: Small Signal (Diode)
Linearized Resistance of Diode
Linearized Diode Circuit
Quiescent Voltage + Incremental
Quiescent Current + Incremental

56. Small Signal Analysis of Forward Bias Diode
Neglect the higher order terms
Based on the condition
Final condition of small signal

57. A two-port network is an electrical network with two pairs of
terminals to connect to external circuits.
Two terminals constitute a port if the currents applied to them
satisfy the essential requirement known as the port condition:
the current entering one terminal must equal the current
emerging from the other terminal on the same port.
The ports constitute interfaces where the network connects to
other networks, the points where signals are applied, or outputs
are taken.
Two - Port Network

58. A 2-port network in electronics is a fundamental concept used to
analyze and describe the behavior of electrical circuits or
systems with two input terminals and two output terminals.
These networks are used to model and understand the
interaction of electrical signals as they pass through various
components, such as amplifiers, filters, transformers, and
transmission lines.
Two - Port Network
The voltage at port 1 (V1)
The current at port 1 (I1)
The voltage at port 2 (V2)
The current at port 2 (I2)

59. Input Ports: These are the two terminals where electrical signals are
applied as inputs to the network. The signals entering the network can be
voltage or current, depending on the specific application.
Output Ports: These are the two terminals from which the network
delivers its output signals. Like the input, the output signals can also be
voltage or current.
Characteristics and Parameters of 2-port networks

60. Transfer Parameters (T-parameters): Another set of parameters used to describe 2-
port networks is the transfer parameters (T-parameters). These parameters relate input
to output in terms of voltage and current, providing insight into how the network
transforms signals.
Hybrid Parameters (H-parameters): Hybrid parameters describe the network in terms
of input current and output voltage (or vice versa). They are particularly useful for
analyzing transistors and other semiconductor devices.
Impedance Parameters (Z-parameters): Impedance parameters describe the network
in terms of input and output impedance, which is valuable for matching networks and
impedance transformations.
Admittance Parameters (Y-parameters): Admittance parameters describe the
network in terms of input and output admittance, which is also useful for certain types
of analysis.
Characteristics and Parameters of 2-port networks

61. 2-port networks are used extensively in Electronics, Telecommunications,
and RF (radio frequency) engineering to analyze, design, and optimize
circuits and systems.
They allow engineers to understand how components interact with signals
and to predict the overall performance of complex systems.
These networks are essential tools in fields such as microwave
engineering, antenna design, and amplifier design, among others.
Applications: Two-port Networks

62. 3-Step Process for Converting Non-linear to Linear
Step – 1:
Step – 2:
Step – 3:
Note the notation also
It is used to
figure out the
total current
and voltage
This kind of notations are
inconvenient in representation

63. Two-Port Non-linear Network Representation
To find out what
is the relation
between currents
I1 and I2
What is the
gain of the
system?
2-PORT Network
representation

64. Two-Port Non-linear Network
Current IDC is dropped from the
argument as it will NOT change the
argument
Quiescent Network
For neglecting
Incremental current
Quiescent Condition

65. Two-Port Non-linear Network
Y11
Y12
Y21
Y22
All the derivatives
(Y) are constants

66. Two-Port Non-linear Network

67. Two-Port Non-linear Network

68. Summary: Two-Port Non-Linear Network

69. Relation: Input Voltage and Output Current

70. Relation: Input Voltage and Output Current

71. Relation: Input Voltage and Output Current

72. Relation: Input Voltage and Output Current

73. Incremental Gain of a Non-Linear Two Port Network

74. Incremental Gain of a Non-Linear Two Port Network

75. Representation of a Non-Linear Two-Port Network
Based on the assumed condition

76. I-V Characteristics of the Non-Linear Two Port
Network

77. Desirable I-V Characteristics of the Non-Linear Two
Port Network

78. Revision of the Non-Linear Two Port Network

79. Desirable I-V Characteristics of the Non-Linear Two
Port Network for Power Amplification
For Reference

80. Desirable I-V Characteristics of the Non-Linear Two
Port Network for Power Amplification

81. Desirable I-V Characteristics of the Non-Linear Two
Port Network for Power Amplification

82. Desirable I-V Characteristics of the Non-Linear Two
Port Network for Power Amplification

83. MOSFET

84. MOSFET

85. MOSFET

86. MOSFET

87. MOSFET

88. I-V Characteristics of the MOSFET

89. I-V Characteristics of the MOSFET

90. I-V Characteristics of the MOSFET

91. I-V Characteristics of the MOSFET

92. I-V Characteristics of the MOSFET

93. I-V Characteristics of the MOSFET

94. I-V Characteristics of the MOSFET

95. I-V Characteristics of the MOSFET

96. I-V Characteristics of the MOSFET
(Common Source)

97. I-V Characteristics of the MOSFET

98. I-V Characteristics of the MOSFET

99. I-V Characteristics of the MOSFET

100. I-V Characteristics of the MOSFET