Bridging Theory in Practice

1
Bridging Theory in Practice

• Transferring Technical Knowledge
• to Practical Applications

2
Transistors andIntegrated Circuits
3
Transistors and Integrated Circuits
4
Transistors andIntegrated Circuits

• Intended Audience
• Engineers with little or no semiconductor
  background
• A basic understanding of electricity is assumed
• Topics Covered
• Bipolar Junction Transistors (BJTs)
• Metal Oxide Semiconductor Field Effect
  Transistors (MOSFETs)
• Integrated Circuits
• Moores Law
• Expected Time
• Approximately 90 minutes

5
Transistors andIntegrated Circuits

• Bipolar Junction Transistors
• Regions of Operation
• Current Control Device
• Equations and Models
• Basic Bias Circuit
• Metal Oxide Semiconductor Field Effect
  Transistors
• Regions of Operation
• Voltage Control Device
• Equations and Models
• Inverter Circuit
• Integrated Circuits
• Moores Law

6
Transistors andIntegrated Circuits

• Bipolar Junction Transistors
• Regions of Operation
• Current Control Device
• Equations and Models
• Basic Bias Circuit
• Metal Oxide Semiconductor Field Effect
  Transistors
• Regions of Operation
• Voltage Control Device
• Equations and Models
• Inverter Circuit
• Integrated Circuits
• Moores Law

7
Bipolar Regions of Operation
Collector
IC
Device On
Device Partly On
Base
IB
IE
IE IC IB
Device Off
Device On Upside Down
Emitter
8
Bipolar Regions of Operation
Collector
IC
Base
IB
Emitter
9
Transistors andIntegrated Circuits

• Bipolar Junction Transistors
• Regions of Operation
• Current Control Device
• Equations and Models
• Basic Bias Circuit
• Metal Oxide Semiconductor Field Effect
  Transistors
• Regions of Operation
• Voltage Control Device
• Equations and Models
• Inverter Circuit
• Integrated Circuits
• Moores Law

10
Bipolar Transistors Are Current Controlled
Devices
Saturation

• For a specific bias configuration (VCE), the
  collector current is determined by the base
  current
• Circuits with bipolar transistors are designed to
  provide the required amount of base current

IB 5
Active
IB 4
IB 3
IB 2
IB 1
11
Bipolar Transistor Gain (b)

• In ACTIVE mode, the collector current is almost
  constant

Saturation
IB 5
Active
IB 4
IB 3
IB 2
IB 1
12
Bipolar Transistor Gain (b)
Saturation

• The BJT gain (b) in active mode is defined as
• b IC / IB
• Sometimes, the gain is also given as
• hFE IC / IB

IB 5
Active
IB 4
IB 3
IB 2
IB 1
13
Bipolar Transistor Gain (b)

• The BJT gain is somewhat independent of the
  collector current

1000
800
600
500
ß
400
300
25C
200
100
1mA
10mA
100mA
0.1mA
0.01mA
Collector Current
14
Bipolar Transistor Gain (b)

• In the ACTIVE mode, fluctuations in base current
  result in amplified fluctuations in collector
  current

Current
time
15
Bipolar Transistor Gain (b)

• In the ACTIVE mode, fluctuations in base current
  result in amplified fluctuations in collector
  current

b IC / IB
Current
b
b
b
time
16
Transistors andIntegrated Circuits

• Bipolar Junction Transistors
• Regions of Operation
• Current Control Device
• Equations and Models
• Basic Bias Circuit
• Metal Oxide Semiconductor Field Effect
  Transistors
• Regions of Operation
• Voltage Control Device
• Equations and Models
• Inverter Circuit
• Integrated Circuits
• Moores Law

17
Bipolar Junction Transistor Ebers-Moll Model
(1954)
Collector
IC
Base
IB
Emitter
18
Bipolar Junction Transistor Performance vs.
Temperature

• As temperature increases, the gain of the BJT
  increases

1000
700
500
ß
300
200
100
1mA
10mA
100mA
0.1mA
0.01mA
19
Bipolar Junction Transistor Performance vs.
Temperature

• Since the gain of the transistor increases with
  temperature, THERMAL RUN AWAY can occur

• As the temperature increases, the gain increases
• As the gain increases, the collector current
  increases
• As the collector current increases, more power is
  dissipated
• As more power is dissipated, the temperature
  increases
• Go back to step 1.

• As the temperature increases, the gain increases
• As the gain increases, the collector current
  increases
• As the collector current increases, more power is
  dissipated
• As more power is dissipated, the temperature
  increases

• As the temperature increases, the gain increases
• As the gain increases, the collector current
  increases
• As the collector current increases, more power is
  dissipated

• As the gain increases, the collector current
  increases

• As the temperature increases, the gain increases

• As thermal run away begins, it can move the BJT
  away from the expected operating bias point
• Eventually, if the temperature of the device
  increases above the maximum rated junction
  temperature (TJUNCTION,MAX), the bipolar
  transistor can be damaged or destroyed

20
Bipolar Junction Transistor Deviations from Ideal
Curves

• Original Ideal Curve

IC
IB 5
Active
IB 4
IB 3
IB 2
IB 1
IB 0
VCE
21
Bipolar Junction Transistor Deviations from Ideal
Curves

• Early Effect Gain (b) increases with Collector
  Emitter Voltage

IC
IB 5
Active
IB 4
IB 3
IB 2
IB 1
IB 0
VCE
22
Bipolar Junction Transistor Deviations from Ideal
Curves

• Above VCEO, the BJT does not function as
  expected...

IC
IB 5
Active
IB 4
IB 3
IB 2
IB 1
IB 0
VCE
VCEO
23
Transistors andIntegrated Circuits

• Bipolar Junction Transistors
• Regions of Operation
• Current Control Device
• Equations and Models
• Basic Bias Circuit
• Metal Oxide Semiconductor Field Effect
  Transistors
• Regions of Operation
• Voltage Control Device
• Equations and Models
• Inverter Circuit
• Integrated Circuits
• Moores Law

24
Bipolar Transistor Biasing
5V
4?
Collector
30W
Base
ß 100
1V
Emitter
25
Bipolar Transistor Biasing
5V

• Operating as an amplifier

4?
Collector
1mVpp
30W
Base
b 100
1V
Emitter
26
Bipolar Transistor Biasing
5V

• Operating as an amplifier

4?
vC 13.3mVpp
VC 1V
Collector
1mVpp
30W
Base
b 100
IB 10mA
1V
Emitter
27
Bipolar Transistor Biasing
5V

• Operating as an amplifier

4?
Collector
1mVpp
30W
Base
b 100
1V
Emitter
28
Bipolar Transistor BiasingWorst Case Analysis
5V

• Operating as an amplifier

4?
Collector
1mVpp
30W
?max 200 ?typ 100 ?min 50
Base
1V
VBE,max 0.8V VBE,typ 0.7V VBE,min 0.5V
Emitter
29
Bipolar Transistor BiasingWorst Case Analysis
Collector Voltage
VBE
0.5V
0.7V
0.8V
1.67V 6.67mV
3.00V 6.67mV
3.67V 6.67mV
50
Circuit Fails
1.00V 13.3mV
2.33V 13.3mV
?
100
Circuit Fails
Circuit Fails
Circuit Fails
200
30
Transistors andIntegrated Circuits

• Bipolar Junction Transistors
• Regions of Operation
• Current Control Device
• Equations and Models
• Basic Bias Circuit
• Metal Oxide Semiconductor Field Effect
  Transistors
• Regions of Operation
• Voltage Control Device
• Equations and Models
• Inverter Circuit
• Integrated Circuits
• Moores Law

31
MOSFET Two BasicRegions of Operation
ID
Drain
ID
Above (Super) Threshold
Gate
VGS
Source
32
MOSFET Super Threshold Regions of Operation
Linear Region
Drain
Saturation Region
VGS 5V
ID
VGS 4V
Gate
VGS 3V
VGS 2V
VGS 1V
Sub-threshold Region
VGS 0V
Source
33
Transistors andIntegrated Circuits

• Bipolar Junction Transistors
• Regions of Operation
• Current Control Device
• Equations and Models
• Basic Bias Circuit
• Metal Oxide Semiconductor Field Effect
  Transistors
• Regions of Operation
• Voltage Control Device
• Equations and Models
• Inverter Circuit
• Integrated Circuits
• Moores Law

34
MOSFETs Are Voltage Controlled Devices

• For a specific bias configuration (VDS), the
  drain current is determined by the gate-source
  voltage
• Circuits with MOSFETs are designed to provide the
  required amount of gate voltage

VGS 5
VGS 4
VGS 3
VGS 2
VGS 1
VGS 0
35
MOSFET Transconductance (gm)

• The MOSFET gain (b) in active mode is NOT defined
  as
• b ID / VGS
• Rather, we speak of a MOSFET's tranconductance
• gm?ID/ ?VGS

VGS 5
VGS 4
VGS 3
VGS 2
VGS 1
VGS 0
36
Transistors andIntegrated Circuits

• Bipolar Junction Transistors
• Regions of Operation
• Current Control Device
• Equations and Models
• Basic Bias Circuit
• Metal Oxide Semiconductor Field Effect
  Transistors
• Regions of Operation
• Voltage Control Device
• Equations and Models
• Inverter Circuit
• Integrated Circuits
• Moores Law

37
MOSFET Equationsand Models

• Square Law Model
• Simple, easy for hand calculations
• Inaccurate for modern devices
• Bulk Charge Theory
• Moderately complex for hand calculations
• Inaccurate for modern devices
• Charge Sheet Model
• Complex
• Almost as accurate as the exact charge model
• Exact Charge Model
• Very complex
• Very accurate for older and modern devices

38
MOSFET Square Law Model

• Subthreshold Region
• Linear Region
• Saturation Region

G a t e
S o u r c e
D r a i n
ID 0A
W
L
ID ( ??ox / tox ) ( W / L ) ( VGS VT )VDS -
VDS2/2
ID ( ??ox / 2tox )( W / L )(VGS VT)2
39
Transistors andIntegrated Circuits

• Bipolar Junction Transistors
• Regions of Operation
• Current Control Device
• Equations and Models
• Basic Bias Circuit
• Metal Oxide Semiconductor Field Effect
  Transistors
• Regions of Operation
• Voltage Control Device
• Equations and Models
• Inverter Circuit
• Integrated Circuits
• Moores Law

40
n-Channel MOSFET (nMOS)Acting as a Switch
Switch is Off VGate 0V
Switch is On VGate VDrain
VDrain 5V
VDrain 5V
IDrain
VGate 0V
VGate 5V
VSource 0V
VSource 0V
41
p-Channel MOSFET (pMOS)Acting as a Switch
Switch is Off VGate VSource
Switch is On VGate 0V
VSource 5V
VSource 5V
IDrain
VGate 5V
VGate 0V
VDrain 0V
VDrain 0V
42
Complementary MOSFET CMOS Inverter
5V
In
Out
0V
43
Complementary MOSFET CMOS Inverter
5V
In 0V
Out
0V
44
Complementary MOSFET CMOS Inverter
5V
In 0V
Out
With VGate 0V, a nMOS transistor does not form
a channel
0V
45
Complementary MOSFET CMOS Inverter
5V
In 0V
Out
With VGate 0V, a nMOS transistor does not form
a channel
Switch OFF
0V
46
Complementary MOSFET CMOS Inverter
5V
With VGate 0V, a pMOS transistor does form a
channel
In 0V
Out
With VGate 0V, a nMOS transistor does not form
a channel
Switch OFF
0V
47
Complementary MOSFET CMOS Inverter
5V
With VGate 0V, a pMOS transistor does form a
channel
Switch ON
In 0V
Out
With VGate 0V, a nMOS transistor does not form
a channel
Switch OFF
0V
48
Complementary MOSFET CMOS Inverter
5V
With VGate 0V, a pMOS transistor does form a
channel
Switch ON
Current tries to flow
In 0V
Out
With VGate 0V, a nMOS transistor does not form
a channel
Switch OFF
0V
49
Complementary MOSFET CMOS Inverter
5V
With VGate 0V, a pMOS transistor does form a
channel
Switch ON
Current tries to flow
In 0V
Out 5V
With VGate 0V, a nMOS transistor does not form
a channel
Switch OFF
0V
50
Complementary MOSFET CMOS Inverter
51
Complementary MOSFET CMOS Inverter
5V
With VGate 5V, a pMOS transistor does not form
a channel
In 5V
Out
0V
52
Complementary MOSFET CMOS Inverter
5V
With VGate 5V, a pMOS transistor does not form
a channel
Switch OFF
In 5V
Out
0V
53
Complementary MOSFET CMOS Inverter
5V
With VGate 5V, a pMOS transistor does not form
a channel
Switch OFF
In 5V
Out
With VGate 5V, a NMOS transistor does form a
channel
0V
54
Complementary MOSFET CMOS Inverter
5V
With VGate 5V, a pMOS transistor does not form
a channel
Switch OFF
In 5V
Out
With VGate 5V, a NMOS transistor does form a
channel
Switch ON
0V
55
Complementary MOSFET CMOS Inverter
5V
With VGate 5V, a pMOS transistor does not form
a channel
Switch OFF
In 5V
Out
With VGate 5V, a NMOS transistor does form a
channel
Switch ON
Current flows
0V
56
Complementary MOSFET CMOS Inverter
5V
With VGate 5V, a pMOS transistor does not form
a channel
Switch OFF
In 5V
Out 0V
With VGate 5V, a NMOS transistor does form a
channel
Switch ON
Current flows
0V
57
Complementary MOSFET CMOS Inverter
In 0V 5V
Out 5V 0V
NMOS Off On
PMOS On Off
58
CMOS InverterWorst Case Analysis

• Logic functions are often less susceptible to
  variations
• Both semiconductor component and system
  variations, however, can impact the CMOS logic
  performance
• Ambient Temperature
• Junction Temperature
• System Voltage
• Input Voltage Levels
• Timing
• Transistor Threshold Voltages
• Capacitances

59
Transistors andIntegrated Circuits

• Bipolar Junction Transistors
• Regions of Operation
• Current Control Device
• Equations and Models
• Basic Bias Circuit
• Metal Oxide Semiconductor Field Effect
  Transistors
• Regions of Operation
• Voltage Control Device
• Equations and Models
• Inverter Circuit
• Integrated Circuits
• Moores Law

60
Integrated Circuits

• Multiple devices can be placed on a single
  semiconductor die
• This allows the design and manufacture of
  integrated circuits

Output
SiO2
p
p
n
n
n-well
p-type substrate
61
Parasitic Resistances and Capacitances
Source
Drain
Gate
SiO2
n
n
p-type
62
Parasitic Resistances and Capacitances
Source
Drain
Gate
Rg
Rd
Rs
Cdo
Cdo
SiO2
Cg
Cif
Cif
Cof
Cof
Cd
n
n
Cj
Cj
p-type
63
Transistors andIntegrated Circuits

• Bipolar Junction Transistors
• Regions of Operation
• Current Control Device
• Equations and Models
• Basic Bias Circuit
• Metal Oxide Semiconductor Field Effect
  Transistors
• Regions of Operation
• Voltage Control Device
• Equations and Models
• Inverter Circuit
• Integrated Circuits
• Moores Law

64
Moores Law

• Gordon E. Moore
• Cramming more components onto integrated
  circuits,
• Electronics, Volume 38, Number 8, April 19,
  1965.
• The complexity for minimum component costs has
  increased
• at a rate of roughly a factor of two per year...
  Certainly over
• the short term this rate can be expected to
  continue, if not
• increase.

65
Moores Law
65536
32768
16384
8192
4096
2048
1024
512
of Integrated Components
256
128
64
32
16
8
4
2
1
1959
1961
1963
1965
1967
1969
1971
1973
1975
66
Moores LawDay of Reckoning
Clearly, we will be able to build such
component-crammed equipment. Next, we ask under
what circumstances we should do it. The total
cost of making a particular system function must
be minimized...." "It may prove to be more
economical to build large systems out of smaller
functions, which are separately packaged and
interconnected.
67
Moores LawDay of Reckoning
105
1962
104
1965
103
Relative Manufacturing Cost / Component
1970
102
10
1
1
10
102
103
104
105
Number of Components per Integrated Circuit
68
Transistors andIntegrated Circuits

• Bipolar Junction Transistors
• Regions of Operation
• Current Control Device
• Equations and Models
• Basic Bias Circuit
• Metal Oxide Semiconductor Field Effect
  Transistors
• Regions of Operation
• Voltage Control Device
• Equations and Models
• Inverter Circuit
• Integrated Circuits
• Moores Law

69
Transistors andIntegrated Circuits

70
Chart Slide
71
End Slide