Mixed-Signal-Electronics - Lehrstuhl für Technische Elektronik - TUM

Mixed-Signal-Electronics
PD Dr.-Ing. Henzler
Prof. Dr. Schmitt-Landsiedel
Lehrstuhl für Technische Elektronik
Technische Universität München
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
1

Mixed-Signal-Team
Prof. Dr. Schmitt-Landsiedel
dsl@tum.de
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
PD Dr. Henzler
henzler@tum.de
2

Stephan‟s ambition for this course …
Simplicity is the Ultimate Sophistication
Leonardo Da Vinci
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
But don‟t misunderstand,
this does not mean that you
don‟t have to exercise!
3

Course and Online Material
Lecture notes
available in the Fachschaft EI (TUM), handout (GIST TUM Asia)
Online material comprising
– annotated slides
– video stream of past lectures (GIST TUM Asia)
www.lte.ei.tum.de/homes/henzler
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
4

Student Discussion Forum
Ask questions online … other students can benefit, too
Try to answer other questions … improves your
understanding
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
5

Administratives
Lecture: Stephan Henzler
henzler@tum.de
office hours: online consultation
Tutorial: Nasim Pour Aryan
n.aryan@tum.de
office hours online & by arrangement
Exam: in written form,
preliminary date February, 14th 2012, 14:00 (TUM)
Credits: 4.5 ECTS credits (TUM)
Language: english
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
6

“Today everything is digital –
Why do we need Mixed-Signal-Electronics?”
Digital System, e.g.
- digital communication
(DSL, GSM, …, LTE)
- computer equipment
- multimedia
(DVD, mp3, camera… )
- control application
(e.g. automotive)
discrete sequence of
numbers from a discrete set
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
7

The Macroscopic World is Purely Analog
motion/acceleration
mechanical force
sound waves
light
electromagnetic
field
Digital System, e.g.
- digital communication
(DSL, GSM, …, LTE)
- computer equipment
- multimedia
(DVD, mp3, camera… )
- control application
(e.g. automotive)
discrete sequence of
numbers from a discrete set
The mixed-signal shell is a bridge between
temperature sense organs
– the analog environment and the digital signal processing
– the physical representation (voltage/current) and a mathematical abstraction
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
sensors/
actuators
time
even „digital‟
signals on a
transmission
channel
8

The Macroscopic World is Purely Analog
motion/acceleration
mechanical force
sound waves
light
electromagnetic
field
ADC
DAC
Digital System, e.g.
- digital communication
(DSL, GSM, …, LTE)
- computer equipment
- multimedia
(DVD, mp3, camera… )
- control application
(e.g. automotive)
discrete sequence of
numbers from a discrete set
The mixed-signal shell is a bridge between
temperature sense organs
– the analog environment and the digital signal processing
– the physical representation (voltage/current) and a mathematical abstraction
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
sensors/
actuators
time
even „digital‟
signals on a
transmission
channel
9

Generic Mixed Signal System
What means mixed-signal?
Mixed-signal refers to a system which processes both analog
and digital signals and which contains converter blocks that
enable interaction between the two domains.
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
10

Topics of MSE Course
Structure of mixed signal systems and mathematical
representation of discrete time signals.
ADC
discrete time
discrete states
discrete time (step function)
continuous states
Lecturer Page Version
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
digital discrete time (step function)
discrete values (states)
11

Sample & hold circuits
Topics of MSE Course
Switched-capacitor circuits
Data converter fundamentals (ADC, DAC)
converter parameters and characteristics
Nyquist rate D/A Converters
Nyquist rate A/D Converters
Oversampling Converters
Outlook: More mixed signal building blocks
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
12

Recommended Literature
David A. Jones
Ken Martin
Analog Integrated Circuit Design
(no picture for copyright reasons)
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
Relevant chapters:
Chapter 7:
Comparators.
Chapter 8:
Sample-and-Holds
Chapter 9:
Discrete Time Signals
Chapter 10:
Switched Capacitor Circuits
Chapter 11:
Data Converter Fundamentals
Chapter 12:
Nyquist-Rate D/A Converters
Chapter 13:
Nyquist-Rate A/D Converters
Chapter 14:
Oversampling Converters
13

Additional Literature & References
Razavi. Principles of Data Conversion System Design.
Wiley, 1994.
Allen, Holberg. CMOS Analog Circuit Design. Oxford, 2010.
Baker, Li, Boyce. CMOS Circuit Desig, Layout, Simulation.
Wiley, 1997.
Gregorian, Temes. Analog MOS Integrated Circuits for
Signal Processing. Wiley 1986.
Oppenheim. Zeitdiskrete Signalverarbeitung. Oldenbourg
1999.
Norsworthy, Schreier, Temes. Delta-Sigma Data
Converters. IEEE Press, 1997.
Schreier, Temes. Understanding Delta Sigma Data
Converters. IEEE Press 2005.
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
14

Constraints of Mixed Signal Circuits in SoC
PROS CONS
• Cheap implementation of complex
signal processing tasks
• System-on-chip (SOC)
Small pcb footprint
• Fast time reference/clock
• Digitally assisted analog
• All advantages of digital
systems, e.g. robustness, noise
immunity, data storage,
reconfigurability, efficient highly
automated design and test
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
• Need to build analog circuits in
digital process, i.e.
• Devices optimized for high
switching speed not for analog,
(e.g. small gm/gds)
• Transistors with high field
and short channel effects
µ(V G), V th(W,L,V DS,V BS), I gate, I DB
• Signal contamination due to digital
switching noise, e.g. cross talk,
supply noise substrate coupling
• several 100mA digital currents
• V analog signals
15

Generic Structure of Mixed-Signal Systems
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
16

Representation of Discrete Time Signals and
Spectral Transformation
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
17

Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12 18

Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12 19

Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
20

Representation of Discrete Time Signals and
Spectral Transformation
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
21

Representation of Discrete Time Signals and
Spectral Transformation
Spectrum of a sampled signal:
s(t) = X
±(t ¡ nT ) $ S(!) = 2¼
T
n
xs(t) = xc(t) ¢ s(t) $
Sampling means multiplication
of continuous time signal with
pulse train
X
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
k
±(! ¡ k!s) !s = 2¼
T
Xs(!) = 1
2¼ Xc(!) ¤ S(!)
= 1
T Xc(!) ¤ X
= 1
T
X
k
In frequency domain this translates
into convolution of signal spectrum
with spectrum of pulse train.
This is simply a copy and shift of
the spectrum to multiples of the
sampling frequency
k
Xc(! ¡ k!s)
±(! ¡ k!s)
22

Representation of Discrete Time Signals and
Spectral Transformation
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
23

Aliasing in the Frequency Domain
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
t
t
t
t
t
t
24

amplitude fsampling = 1 f signal,1 = 0.22
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
Sampling and Aliasing 1
0 5 10 15
samples
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
25

amplitude fsampling = 1 f signal,2 = 0.22 + fsampling
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
Sampling and Aliasing 2
0 5 10 15
samples
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
26

amplitude
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
Sampling and Aliasing 3
Only with the Nyquist criterion it is assured that the samples
represent the signal unambiguously
0 5 10 15
samples
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
27

Remember: All realizable signals have
–
–
–
Practical Sampling: Sample & Hold
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
t
t
t
28

Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
29

Practical Sampling: Sample & Hold
Remember: All realizable signals have
– finite slope
– finite pulse width
– finite bandwidth
– finite value
Hence sampling means always SAMPLE & HOLD
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
30

Sampling with Finite Pulse Width
x sh(t) = xs(t) ¤ h(t)
=
x sh(!) = 1
¿
= 1
¿
1X
n=¡1
+1
Z
¡1
1X
= ¡ 1
j!¿
xc[n] 1
¿ [¾(t ¡ nT ) ¡ ¾(t ¡ nT ¡ ¿)]
1X
n=¡1
n=¡1
1X
xc[n]
n=¡1
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
xc[n] [¾(t ¡ nT ) ¡ ¾(t ¡ nT ¡ ¿)] e ¡j!t dt
nT +¿
Z
nT
e ¡j!t dt
xc[n] h
e ¡j!ti nT +¿
nT
(t)
t
31

Xsh(!) = ¡ 1
j!¿
Sampling with Finite Pulse Width
=
1X
n=¡1
Distortion of base band and damping of mirror spectra
– visible in DAC
– not visible in ADC
1X
n=¡1
xc[n]e ¡j!nT
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
xc[n] ³
e ¡j!nT e ¡j!¿ ´
¡ e
j!nT
1
j!¿
= Xs(!)e ¡1 2j!¿ ej 1 2 !¿ ¡ e ¡j 1 2 !¿
2j 1 2 !¿
= Xs(!)e ¡j 1 2 !¿ sin ³ 1
2 !¿ ´
³
´
1 ¡ e
¡j!¿
ideal sampling X S() impact of hold
1
2 !¿
32

Representation of Discrete Time Signals and
Spectral Transformation
Henzler, Schmitt-Landsiedel Mixed-Signal-Electronics 2011/12
33