Digital Integrated Circuits – EECS...
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Digital Integrated Circuits – EECS 312 http://robertdick.org/eecs312/ Teacher: Robert Dick Office: 2417-E EECS Email: [email protected] Phone: 734–763–3329 Cellphone: 847–530–1824 GSI: Shengshou Lu Office: 2725 BBB Email: [email protected] HW engineers SW engineers 0 1 2 3 4 5 6 7 8 9 10 200 220 240 260 280 300 Current (mA) Time (seconds) Typical Current Draw 1 sec Heartbeat 30 beats per sample Sampling and Radio Transmission 9 - 15 mA Heartbeat 1 - 2 mA Radio Receive for Mesh Maintenance 2 - 6 mA Low Power Sleep 0.030 - 0.050 mA Year of announcement 1950 1960 1970 1980 1990 2000 2010 Power density (Watts/cm 2 ) 0 2 4 6 8 10 12 14 Bipolar CMOS Vacuum IBM 360 IBM 370 IBM 3033 IBM ES9000 Fujitsu VP2000 IBM 3090S NTT Fujitsu M-780 IBM 3090 CDC Cyber 205 IBM 4381 IBM 3081 Fujitsu M380 IBM RY5 IBM GP IBM RY6 Apache Pulsar Merced IBM RY7 IBM RY4 Pentium II(DSIP) T-Rex Squadrons Pentium 4 Mckinley Prescott Jayhawk(dual) IBM Z9
Transcript of Digital Integrated Circuits – EECS...
Digital Integrated Circuits – EECS 312
http://robertdick.org/eecs312/
Teacher: Robert DickOffice: 2417-E EECSEmail: [email protected]: 734–763–3329Cellphone: 847–530–1824
GSI: Shengshou LuOffice: 2725 BBBEmail: [email protected]
HW engineers SW engineers
0
1
2
3
4
5
6
7
8
9
10
200 220 240 260 280 300
Cu
rre
nt
(mA
)
Time (seconds)
Typical Current Draw 1 sec Heartbeat
30 beats per sample
Sampling andRadio Transmission
9 - 15 mA
Heartbeat1 - 2 mA
Radio Receive for
Mesh Maintenance
2 - 6 mA
Low Power Sleep0.030 - 0.050 mA
Year of announcement
1950 1960 1970 1980 1990 2000 2010
Pow
er d
ensi
ty (
Wat
ts/c
m2 )
0
2
4
6
8
10
12
14
Bipolar
CMOS
VacuumIBM 360
IBM 370 IBM 3033
IBM ES9000
Fujitsu VP2000
IBM 3090S
NTT
Fujitsu M-780
IBM 3090
CDC Cyber 205IBM 4381
IBM 3081Fujitsu M380
IBM RY5
IBM GP
IBM RY6
Apache
Pulsar
Merced
IBM RY7
IBM RY4
Pentium II(DSIP)
T-Rex
Squadrons
Pentium 4
Mckinley
Prescott
Jayhawk(dual)
IBM Z9
Most confusing points for the weekDiodes
Homework
Lecture plan
1. Most confusing points for the week
2. Diodes
3. Homework
2 Robert Dick Digital Integrated Circuits
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Homework
Policy on confusing points
If it doesn’t make sense, I will either
1 cover it in more detail right away,
2 indicate when it will be covered in detail, or
3 invite you to office hours.
3 Robert Dick Digital Integrated Circuits
Most confusing points for the weekDiodes
Homework
Why and when does an NMOS-based consume more power
than a CMOS inverter?
If R is big, low→high output transition is slow.
If R is slow, constant power consumption whenever input is high.
Derive and explain.
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Homework
What is leakage power consumption? What is dynamic
power consumption?
Subthreshold leakage: not a perfect switch at Vt .
Gate leakage.
Dynamic power.
Derive and explain.
5 Robert Dick Digital Integrated Circuits
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Homework
What is the difference between a source and drain?
Source is the side the charge carriers for the MOSFET comefrom.
Drain is the side to which the charge carriers go.
Key question: Which terminal has a higher voltage and which
terminal has a lower voltage?
Derive and explain.
6 Robert Dick Digital Integrated Circuits
Most confusing points for the weekDiodes
Homework
Lecture plan
1. Most confusing points for the week
2. Diodes
3. Homework
7 Robert Dick Digital Integrated Circuits
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Homework
Why diodes?
In the process of building MOSFETs, we accidentally makediodes.
Must understand their properties.
What we learn about device physics here will help us understandMOSFETs in later lectures.
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Homework
Diode physical structure
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Step-by-step diode explanation
1 Dope regions with donors and acceptors.
2 N- and P-doped regions are in contact.
3 Diffusion according to diffusion equation.
4 Drift due to electrical field causes drift–diffusion effects to reachsteady-state.
5 Left with built-in potential, and depletion region (without mobilecharge carriers) near junction.
6 Reverse bias (making P voltage lower than N voltage) just makesdepletion region bigger.
7 Forward bias at first reduces depletion region width, then allowsmobile electrons and holes to combine at junction — suddenincrease in current!
8 At extreme reverse bias, the few mobile carriers that get into thedepletion region so fast that they collide with silicon atoms,generating electron-hole pairs, chain reaction fills depletion regionwith mobile carriers — sudden increase in current!
Step-by-step diode explanation
1 Dope regions with donors and acceptors.
2 N- and P-doped regions are in contact.
3 Diffusion according to diffusion equation.
4 Drift due to electrical field causes drift–diffusion effects to reachsteady-state.
5 Left with built-in potential, and depletion region (without mobilecharge carriers) near junction.
6 Reverse bias (making P voltage lower than N voltage) just makesdepletion region bigger.
7 Forward bias at first reduces depletion region width, then allowsmobile electrons and holes to combine at junction — suddenincrease in current!
8 At extreme reverse bias, the few mobile carriers that get into thedepletion region so fast that they collide with silicon atoms,generating electron-hole pairs, chain reaction fills depletion regionwith mobile carriers — sudden increase in current!
Most confusing points for the weekDiodes
Homework
Material properties
Heat
Eg
Eg
SemiconductorInsulator
or
Metal
Conduction
Valence
Electron mobility µn is a bit over twice that of hole µp.
Units are cm2
Vs.
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Homework
Example dopants
Example donor: As.
Example acceptor: B.
13 Robert Dick Digital Integrated Circuits
Most confusing points for the weekDiodes
Homework
What are the electrons and holes we have been discussing?
We mean only electrons in the conduction band, not the valenceband.
We mean only holes in the valence band, not the conductionband.
The conduction band is mostly empty for a semiconductor.
The valence band is mostly full for a semiconductor.
14 Robert Dick Digital Integrated Circuits
Step-by-step diode explanation
1 Dope regions with donors and acceptors.
2 N- and P-doped regions are in contact.
3 Diffusion according to diffusion equation.
4 Drift due to electrical field causes drift–diffusion effects to reachsteady-state.
5 Left with built-in potential, and depletion region (without mobilecharge carriers) near junction.
6 Reverse bias (making P voltage lower than N voltage) just makesdepletion region bigger.
7 Forward bias at first reduces depletion region width, then allowsmobile electrons and holes to combine at junction — suddenincrease in current!
8 At extreme reverse bias, the few mobile carriers that get into thedepletion region so fast that they collide with silicon atoms,generating electron-hole pairs, chain reaction fills depletion regionwith mobile carriers — sudden increase in current!
Step-by-step diode explanation
1 Dope regions with donors and acceptors.
2 N- and P-doped regions are in contact.
3 Diffusion according to diffusion equation.
4 Drift due to electrical field causes drift–diffusion effects to reachsteady-state.
5 Left with built-in potential, and depletion region (without mobilecharge carriers) near junction.
6 Reverse bias (making P voltage lower than N voltage) just makesdepletion region bigger.
7 Forward bias at first reduces depletion region width, then allowsmobile electrons and holes to combine at junction — suddenincrease in current!
8 At extreme reverse bias, the few mobile carriers that get into thedepletion region so fast that they collide with silicon atoms,generating electron-hole pairs, chain reaction fills depletion regionwith mobile carriers — sudden increase in current!
Most confusing points for the weekDiodes
Homework
Diffusion equation
∂φ (~r , t)
∂t= ∇ · (D (φ, ~r)∇φ (~r , t))
~r : location
t: time
φ(~r , t): density
D(~r , t): diffusion coefficient
∇: vector differential operator
If D is constant,∂φ (~r , t)
∂t= D∇
2φ (~r , t)
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Diffusion example
0
5
10
15
20
25
Time
0 10
20 30
40 50
60 70
80 90
100
Position
0
0.2
0.4
0.6
0.8
1
V
Derive and explain.Note: Python is awesome.
Step-by-step diode explanation
1 Dope regions with donors and acceptors.
2 N- and P-doped regions are in contact.
3 Diffusion according to diffusion equation.
4 Drift due to electrical field causes drift–diffusion effects to reachsteady-state.
5 Left with built-in potential, and depletion region (without mobilecharge carriers) near junction.
6 Reverse bias (making P voltage lower than N voltage) just makesdepletion region bigger.
7 Forward bias at first reduces depletion region width, then allowsmobile electrons and holes to combine at junction — suddenincrease in current!
8 At extreme reverse bias, the few mobile carriers that get into thedepletion region so fast that they collide with silicon atoms,generating electron-hole pairs, chain reaction fills depletion regionwith mobile carriers — sudden increase in current!
Most confusing points for the weekDiodes
Homework
Junction depletion
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Homework
Drift velocity
The drift velocity vd = µξ, where µ is the mobility and ξ is theelectric field.
Net velocity must be small compared to particle random motionvelocity for this to hold – more on this soon.
20 Robert Dick Digital Integrated Circuits
Step-by-step diode explanation
1 Dope regions with donors and acceptors.
2 N- and P-doped regions are in contact.
3 Diffusion according to diffusion equation.
4 Drift due to electrical field causes drift–diffusion effects to reachsteady-state.
5 Left with built-in potential, and depletion region (without mobilecharge carriers) near junction.
6 Reverse bias (making P voltage lower than N voltage) just makesdepletion region bigger.
7 Forward bias at first reduces depletion region width, then allowsmobile electrons and holes to combine at junction — suddenincrease in current!
8 At extreme reverse bias, the few mobile carriers that get into thedepletion region so fast that they collide with silicon atoms,generating electron-hole pairs, chain reaction fills depletion regionwith mobile carriers — sudden increase in current!
Most confusing points for the weekDiodes
Homework
Built-in potential
Φ0 = ΦT ln
[
NAND
n2i
]
(1)
ΦT =kT
q(2)
ni : intrinsic charge carrier concentration.
Nx : acceptor and donor concentrations.
k : Boltzmann constant
T : temperature
q: elementary charge
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Step-by-step diode explanation
1 Dope regions with donors and acceptors.
2 N- and P-doped regions are in contact.
3 Diffusion according to diffusion equation.
4 Drift due to electrical field causes drift–diffusion effects to reachsteady-state.
5 Left with built-in potential, and depletion region (without mobilecharge carriers) near junction.
6 Reverse bias (making P voltage lower than N voltage) just makesdepletion region bigger.
7 Forward bias at first reduces depletion region width, then allowsmobile electrons and holes to combine at junction — suddenincrease in current!
8 At extreme reverse bias, the few mobile carriers that get into thedepletion region so fast that they collide with silicon atoms,generating electron-hole pairs, chain reaction fills depletion regionwith mobile carriers — sudden increase in current!
Step-by-step diode explanation
1 Dope regions with donors and acceptors.
2 N- and P-doped regions are in contact.
3 Diffusion according to diffusion equation.
4 Drift due to electrical field causes drift–diffusion effects to reachsteady-state.
5 Left with built-in potential, and depletion region (without mobilecharge carriers) near junction.
6 Reverse bias (making P voltage lower than N voltage) just makesdepletion region bigger.
7 Forward bias at first reduces depletion region width, then allowsmobile electrons and holes to combine at junction — suddenincrease in current!
8 At extreme reverse bias, the few mobile carriers that get into thedepletion region so fast that they collide with silicon atoms,generating electron-hole pairs, chain reaction fills depletion regionwith mobile carriers — sudden increase in current!
Most confusing points for the weekDiodes
Homework
Diode operation
24 Robert Dick Digital Integrated Circuits
Most confusing points for the weekDiodes
Homework
Diode current
ID = IS
(
eVDφT − 1
)
ID : diode current
VD : diode voltage
IS : saturation current constant
φT = kTq: thermal voltage
k : Boltzmann constantT : temperatureq: elementary charge
25 Robert Dick Digital Integrated Circuits
Step-by-step diode explanation
1 Dope regions with donors and acceptors.
2 N- and P-doped regions are in contact.
3 Diffusion according to diffusion equation.
4 Drift due to electrical field causes drift–diffusion effects to reachsteady-state.
5 Left with built-in potential, and depletion region (without mobilecharge carriers) near junction.
6 Reverse bias (making P voltage lower than N voltage) just makesdepletion region bigger.
7 Forward bias at first reduces depletion region width, then allowsmobile electrons and holes to combine at junction — suddenincrease in current!
8 At extreme reverse bias, the few mobile carriers that get into thedepletion region so fast that they collide with silicon atoms,generating electron-hole pairs, chain reaction fills depletion regionwith mobile carriers — sudden increase in current!
Most confusing points for the weekDiodes
Homework
Avalanche breakdown
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Most confusing points for the weekDiodes
Homework
Diode capacitance
CJ =CJ0
(1− VD/Φ0)m
m = 0.5 for abrupt junctions, m = 0.33 for linear junctions28 Robert Dick Digital Integrated Circuits
Most confusing points for the weekDiodes
Homework
Diffusion capacitance
CJ0 = AD
√
ǫSiq
2
NAND
NA + ND
1
φ0
AD : area of diode
ǫSi : permittivity of silicon
NX : carrier density
φ0 = φT ln NAND
ni 2
φT = kTq
ni : intrinsic carrier concentration
29 Robert Dick Digital Integrated Circuits
Most confusing points for the weekDiodes
Homework
Summary of basic device physics and diodes
What are the electrons, holes, dopants, and acceptors we havebeen talking about?
What are diffusion and drift?
What is “built-in” potential?
Avalanche breakdown?
Intrinsic carriers?
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Homework
Upcoming topics
Transistor static behavior.
Fabrication.
Transistor dynamic behavior.
Interconnect.
31 Robert Dick Digital Integrated Circuits
Most confusing points for the weekDiodes
Homework
Lecture plan
1. Most confusing points for the week
2. Diodes
3. Homework
32 Robert Dick Digital Integrated Circuits
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Homework
Homework assignment and announcement
12 September: Section 3.3.2 in J. Rabaey, A. Chandrakasan, and
B. Nikolic. Digital Integrated Circuits: A Design Perspective.Prentice-Hall, second edition, 2003.
17 September: Laboratory assignment one.
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