Analog Integrated Circuit Design A video course under the NPTEL Nagendra Krishnapura

Analog Integrated Circuit Design
A video course under the NPTEL
Nagendra Krishnapura
Department of Electrical Engineering
Indian Institute of Technology, Madras
Chennai, 600036, India
National Programme on Technology Enhanced Learning
Nagendra Krishnapura
Analog Integrated Circuit Design
Nagendra Krishnapura: Introduction
www: http://www.ee.iitm.ac.in/∼nagendra
e-mail: [email protected]
Website has reference material, problem sets from other
analog courses, and other resources
Nagendra Krishnapura
Analog Integrated Circuit Design
Modern signal processing systems
Sensor(s)
Digital Processing
Actuator(s)
...
...
DSP
...0100011011...
...
Continuous-time
Continuous-amplitude
Discrete -time
Discrete -amplitude
Continuous-time
Continuous-amplitude
Interface Electronics
(Signal Conditioning)
(A-D and D-A Conversion)
Picture source: Prof. Shanthi Pavan
Nagendra Krishnapura
Analog Integrated Circuit Design
Analog circuits in modern systems on VLSI chips
Analog to digital conversion
Digital to analog conversion
Amplification
Signal processing circuits at high frequencies
Power management-voltage references, voltage regulators
Oscillators, Phase locked loops
The last two are found even on many “digital” ICs
Nagendra Krishnapura
Analog Integrated Circuit Design
Analog circuits in modern systems on VLSI chips
Analog to digital conversion
Digital to analog conversion
Amplification
Signal processing circuits at high frequencies
Power management-voltage references, voltage
regulators
Oscillators, Phase locked loops
The last two are found even on many “digital” ICs
Nagendra Krishnapura
Analog Integrated Circuit Design
Image sensor
Chip Micrograph
Voltage
Regulator
Column
CDS circuits
703 x 499 pixels
(VGA format)
Timing Generator
10b pipelined
ADC
I/O circuit
Chip size: 4.74mm x 6.34mm
H. Takahashi et al., “A 3.9 µm pixel pitch VGA format 10b digital image sensor with 1.5-transistor/pixel,” IEEE
International Solid-State Circuits Conference, vol. XVII, pp. 108 - 109, February 2004.
Nagendra Krishnapura
Analog Integrated Circuit Design
Wireless LAN transceiver
M. Zargari et al., “A single-chip dual-band tri-mode CMOS transceiver for IEEE 802.11a/b/g WLAN,” IEEE
International Solid-State Circuits Conference, vol. XVII, pp. 96 - 97, February 2004.
Nagendra Krishnapura
Analog Integrated Circuit Design
DRAM
64 I/Os
ADDRESSES
AND CONTROL
64 I/Os
BANK 3
ROW
DECODERS
BANK 2
DATA LINES
BANK 1
COLUMN
DECODERS
1088
SENSE AMPS
512K
ARRAY
BANK 0
VPP PUMP
K. Hardee et al. “A 0.6V 205MHz 19.5ns tRC 16Mb embedded DRAM,” IEEE International Solid-State Circuits
Conference, vol. XVII, pp. 200 - 201, February 2004.
Nagendra Krishnapura
Analog Integrated Circuit Design
Analog IC design in India
Many companies starting analog centers
Multinationals and Indian start ups
Big demand for skilled designers
Interesting and profitable activity ⌣
¨
Nagendra Krishnapura
Analog Integrated Circuit Design
Course goals
Learn to design negative feedback circuits on CMOS ICs
Negative feedback for controlling the output
Amplifiers, voltage references, voltage regulators, biasing
Phase locked loops
Filters
Nagendra Krishnapura
Analog Integrated Circuit Design
Course prerequisites
Circuit analysis-small and large signal
Laplace transforms, frequency response, Bode plots,
Differential equations
Ideal opamp circuits; Opamp nonidealities
Single transistor amplifiers, differential pairs
Nagendra Krishnapura
Analog Integrated Circuit Design
Course contents
Nagendra Krishnapura
Analog Integrated Circuit Design
Course contents-Negative feedback amplifiers
Amplifiers using negative feedback
Stability, Frequency compensation
Negative feedback circuits using opamps
Opamp models
Nagendra Krishnapura
Analog Integrated Circuit Design
Course contents-Opamps on CMOS ICs
Components available on a CMOS integrated circuit
Device models-dc small signal, dc large signal, ac small
signal, mismatch, noise
Single stage opamp
Cascode opamps
Two stage opamp with miller compensation
Nagendra Krishnapura
Analog Integrated Circuit Design
Course contents-Fully differential circuits
Differential and common mode half circuits, common mode
feedback
Fully differential miller compensated opamp
Fully differential feedforward compensated opamp
Nagendra Krishnapura
Analog Integrated Circuit Design
Course contents-Phase locked loop
Frequency multiplication using negative feedback
Type I, type II loops
Oscillators
Phase noise basics
PLL noise transfer functions
Nagendra Krishnapura
Analog Integrated Circuit Design
Course contents-Design of opamps
Single stage opamp
Folded, telescopic cascode opamps
Two stage opamp
Fully differential opamps and common mode feedback
Applications: Bandgap reference, constant gm bias
generation
Nagendra Krishnapura
Analog Integrated Circuit Design
Course contents-Applications
Bandgap reference
Constant current and constant gm bias generators
Continuous-time filters
Switched capacitor filters
Nagendra Krishnapura
Analog Integrated Circuit Design
What is design and how do I learn it?
Nagendra Krishnapura
Analog Integrated Circuit Design
Design versus Analysis
Design: Create something that doesn’t yet exist
Analysis: Analyze something that exists
Nagendra Krishnapura
Analog Integrated Circuit Design
To be able to design
Knowing analysis is necessary, not sufficient
Multiple ways of looking at building blocks
Trial and error approaches
Approximations
Intuitive thinking/understanding
Curiosity
Open mind
Thoroughness
Nagendra Krishnapura
Analog Integrated Circuit Design
Intuition
Intuitive thinking is not sloppy thinking!
Relate problems to other problems already solved
Use boundary conditions, dimension checks etc.
Build your intuition
Solve many problems
Think about why the answer is what it is
Come up with the form of the solution before applying full
blown analysis
Nagendra Krishnapura
Analog Integrated Circuit Design
Using these lectures
Nagendra Krishnapura
Analog Integrated Circuit Design
Using these lectures
Take notes as you watch
Work out all the steps in solving a problem—Don’t just
watch it being solved
Expect to spend about three hours to understand an hour
long lecture
Nagendra Krishnapura
Analog Integrated Circuit Design
Brief overview of prerequisites
Nagendra Krishnapura
Analog Integrated Circuit Design
Circuit analysis
Nodal analysis-Kirchoff’s Current Law (KCL) at each node
Solve N simultaneous equations for an N node circuit
Mesh analysis-Kirchoff’s Voltage Law (KVL) around each
loop
Solve M simultaneous equations for a circuit with M
independent loops
Nagendra Krishnapura
Analog Integrated Circuit Design
Nodal analysis
i11 (v ) + i12 (v ) + . . . + i1N (v ) = i1
i21 (v ) + i22 (v ) + . . . + i2N (v ) = i2
..
.
iN1 (v ) + iN2 (v ) + . . . + iNN (v ) = iN
ikl : Current in the branch between nodes k and l
ikk : Current in the branch between node k and ground
vk : Voltage at node k ; v = [v1 v2 . . . vN ]T
ik : Current source into node k
ikl can be a nonlinear function of v
Nagendra Krishnapura
Analog Integrated Circuit Design
Nodal analysis—Linear circuits
g11 v1 + g12 v2 + . . . + g1N vN
= i1
g21 v1 + g22 v2 + . . . + g2N vN
= i2
..
.
gN1 v1 + gN2 v2 + . . . + gNN vN
= iN
gkl : Conductance between nodes k and l
gkk : Conductance between node k and ground
vk : Voltage at node k
ik : Current source into node k
Nagendra Krishnapura
Analog Integrated Circuit Design
Nodal analysis—Independent voltage source
..
.
gk 1 v1 + gk 2 v2 + . . . + gkN vN
vk
= ik
..
.
node k
= Vo
node k
Ideal voltage source Vo connected to node k
Nagendra Krishnapura
Analog Integrated Circuit Design
Nodal analysis—Voltage controlled voltage source
..
.
gk 1 v1 + gk 2 v2 + . . . + gkN vN
= ik
..
.
node k
vk − kvl
= 0
node k
Voltage controlled voltage source vk = kvl driving node k
Nagendra Krishnapura
Analog Integrated Circuit Design
Nodal analysis—Controlled voltage source
gk 1 v1 + gk 2 v2 + . . . + gkl vl + . . . + gkN vN
vk
gk 1 v1 + gk 2 v2 + . . . +
+ . . . + gkN vN
Rm
gl1 v1 + gl2 v2 + . . . + glk vk + . . . + glN vN
v
gl1 v1 + gl2 v2 + . . . − k + . . . + glN vN
Rm
= ik
node k
= ik
node k
= il
node l
= il
node l
Current controlled voltage source vk = Rm ikl driving node k
Nagendra Krishnapura
Analog Integrated Circuit Design
Nodal analysis—Controlled current source
gk 1 v1 + gk 2 v2 + . . . + gkl vl + . . . + gkN vN
gk 1 v1 + gk 2 v2 + . . . + gkl vl − gm vl + . . . + gkN vN
= ik + gm vl
= ik
Voltage controlled current source i0 = gm vl driving node k
Nagendra Krishnapura
Analog Integrated Circuit Design
Nodal analysis—Ideal opamp
..
.
gm1 v1 + gm2 v2 + . . . + gmN vN
= im
..
.
vk − vl
= 0
node m
node m
Ideal opamp with input terminals at nodes k , l and output
at node m
Nagendra Krishnapura
Analog Integrated Circuit Design
Nodal analysis—solution

 
i1
v1
 i2 
  v2 
 
 
  ..  =  .. 
.
 . 
iN
vN
gN1 gN2 . . . gNN

g11 g12 . . . g1N
 g21 g22 . . . g2N


..

.

Gv
v
= i
= G−1 i
gkl : Conductance between nodes k and l
gkk : Conductance between node k and ground
vk : Voltage at node k
ik : Current source into node k
Modified terms for voltage sources or controlled sources
Matrix inversion yields the solution
Nagendra Krishnapura
Analog Integrated Circuit Design
Nodal analysis—solution
vk
=
g11 g12 . . . i1 . . . g1N g21 g22 . . . i2 . . . g2N ..
.
gN1 gN2 . . . iN . . . gNN g11 g12 . . . g1k . . . g1N g21 g22 . . . g2k . . . g2N ..
.
gN1 gN2 . . . gNk . . . gNN Cramer’s rule can be used for matrix inversion
Nagendra Krishnapura
Analog Integrated Circuit Design
Circuits with capacitors and inductors




I1 (s)
V1 (s)
Y11 (s)Y12 (s) . . . Y1N (s)
 I2 (s) 
 Y21 (s)Y22 (s) . . . Y2N (s)   V2 (s) 





=
 .. 
  .. 

..





. 
.
.
IN (s)
VN (s)
YN1 (s)YN2 (s) . . . YNN (s)

Y(s)V (s) = I(s)
V (s) = Y−1 I(s)
Conductances gkl replaced by admittances Ykl (s)
Roots of the determinant of Y(s) are system poles
Nagendra Krishnapura
Analog Integrated Circuit Design
Laplace transform analysis for linear systems
Input
Output
X (s)
H(s)X (s)
e
st
X (jω)
e
jωt
cos(ωt)
H(s)est
H(jω)X (jω)
H(jω)ejωt
|H(jω)| cos (ωt + ∠H(jω))
(Steady state solution)
Linear time invariant system described by its transfer
function H(s)
H(s) is the laplace transform of the impulse response
s = jω implies a sinusoid of frequency ω
Nagendra Krishnapura
Analog Integrated Circuit Design
Laplace transform analysis for linear systems
Transfer function H(s) (no poles at the origin)
1 + b1 s + b2 s 2 + . . . + b M s M
1 + b1 s + b2 s 2 + . . . + b N s N
QM
1 + s/zk
= Adc QNk =1
k =1 1 + s/pk
H(s) = Adc
Single pole at the origin
H(s) =
Q
ωu M
k =1 1 + s/zk
Q
s N
k =2 1 + s/pk
All poles pk must be in the left half plane for stability
Nagendra Krishnapura
Analog Integrated Circuit Design
Frequency and time domain analyses
Frequency domain
Algebraic equations-easier solutions
Only for linear systems
Time domain
Differential equations-more difficult to solve
Can be used for nonlinear systems as well
Piecewise linear systems occur quite frequently (e.g.
saturation)
Nagendra Krishnapura
Analog Integrated Circuit Design
Bode plots
Sinusoidal steady state response characterized by |H(jω)|,
∠H(jω)
Bode plot: Plot of 20 log |H(jω)|, ∠H(jω) versus log ω
approximated by straight line segments
Good approximation for real poles and zeros
Nagendra Krishnapura
Analog Integrated Circuit Design
Simulators
Very powerful tools, indispensable for complex calculations, but
GIGO!
Matlab/Octave: System level analysis (Frequency
response, pole-zero, transfer functions)
Spice: Circuit analysis
Maxima: Symbolic analysis
Nagendra Krishnapura
Analog Integrated Circuit Design
References
Recorded lectures:
http://www.ee.iitm.ac.in/∼nagendra/videolectures
Behzad Razavi, Design of Analog CMOS Integrated Circuits,
McGraw-Hill, August 2000.
Hayt and Kemmerly, Engineering Circuit Analysis, McGraw Hill,
6/e.
B. P. Lathi, Linear Systems and Signals, Oxford University Press,
2 edition, 2004.
Sergio Franco, Design with operational amplifiers and analog
ICs, Tata McGraw Hill.
Nagendra Krishnapura
Analog Integrated Circuit Design