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Bridging Theory in Practice. Transferring Technical Knowledge to Practical Applications. Transistors and Integrated Circuits. Transistors and Integrated Circuits. Transistors and Integrated Circuits. Intended Audience: Engineers with little or no semiconductor background

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Bridging theory in practice

Bridging Theory in Practice

Transferring Technical Knowledge

to Practical Applications


Transistors and integrated circuits

Transistors andIntegrated Circuits


Transistors and integrated circuits1

Transistors and Integrated Circuits


Bridging theory in practice

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

  • Moore’s Law

    Expected Time:

  • Approximately 90 minutes


Bridging theory in practice

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

  • Moore’s Law


Bridging theory in practice

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

  • Moore’s Law


Bipolar regions of operation

Bipolar Regions of Operation

VBE

Active

Saturation

VBC

Cut-Off

Inverted

Collector

IC

Device

On

Device

Partly On

Base

IB

IE

IE = IC + IB

Device

Off

Device On

Upside Down

Emitter


Bipolar regions of operation1

Bipolar Regions of Operation

Saturation

IC

IB = 5

Active

IB = 4

IB = 3

IB = 2

IB = 1

VCE

Cut-Off

IB = 0

Collector

IC

Base

IB

Emitter


Bridging theory in practice

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

  • Moore’s Law


Bipolar transistors are current controlled devices

Bipolar Transistors Are “Current Controlled” Devices

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

IC

VCE

Cut-Off

IB = 0

Saturation

IB = 5

Active

IB = 4

IB = 3

IB = 2

IB = 1


Bridging theory in practice

IC

C

B

IC

IB

VCE

Cut-Off

IB = 0

E

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


Bridging theory in practice

IC

VCE

Cut-Off

IB = 0

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


Bridging theory in practice

At room temperature, β ranges

from 240-290 across

3 orders of magnitude

Bipolar Transistor Gain (b)

  • The BJT gain is somewhat independent of the collector current:

1000

800

600

500

β

400

300

25C

200

100

1mA

0.01mA

0.1mA

10mA

100mA

Collector Current


Bridging theory in practice

Collector Current

Base Current

Bipolar Transistor Gain (b)

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

Current

time


Bridging theory in practice

b

b

b

b

b

b

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


Bridging theory in practice

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

  • Moore’s Law


Bridging theory in practice

Collector

IC

RIR

IR

Base

IB

IF

FIF

-(IB+IC) = IE

Emitter

Bipolar Junction Transistor Ebers-Moll Model (1954)

Collector

IC

Base

IB

Emitter


Bipolar junction transistor performance vs temperature

Bipolar Junction Transistor Performance vs. Temperature

As temperature increases, the gain of the BJT increases

b about doubles

over temperature

1000

700

500

β

300

200

100

1mA

0.01mA

0.1mA

10mA

100mA


Bridging theory in practice

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

Bipolar Junction Transistor Performance vs. Temperature

  • 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


Bipolar junction transistor deviations from ideal curves

Original Ideal Curve

Bipolar Junction Transistor Deviations from Ideal Curves

Saturation

IC

IB = 5

Active

IB = 4

IB = 3

IB = 2

IB = 1

IB = 0

VCE


Bridging theory in practice

Saturation

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


Bridging theory in practice

Saturation

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


Bridging theory in practice

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

  • Moore’s Law


Bridging theory in practice

V = IR = 4V

VC = 1V

IB = (1V – 0.7V) = 10mA

IC= β IB =1A

30

IB

~0.7V

Bipolar Transistor Biasing

5V

4

Collector

30W

Base

β = 100

1V

Emitter


Bridging theory in practice

VC = 1V

IC= β IB =1A

IB = 10mA

~0.7V

Bipolar Transistor Biasing

5V

  • Operating as an amplifier:

4

Collector

1mVpp

30W

Base

b = 100

1V

Emitter


Bridging theory in practice

iB = 1mVpp / 30 = 33App

IC= β IB =1A

iC = 3.3mA

iB

~0.7V

Bipolar Transistor Biasing

5V

  • Operating as an amplifier:

4

vC = 13.3mVpp

VC = 1V

Collector

1mVpp

30W

Base

b = 100

IB = 10mA

1V

Emitter


Bridging theory in practice

Bipolar Transistor Biasing

5V

  • Operating as an amplifier:

4

Collector

1mVpp

30W

Base

b = 100

1V

Emitter


Bipolar transistor biasing worst case analysis

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


Bipolar transistor biasing worst case analysis1

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


Bridging theory in practice

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

  • Moore’s Law


Bridging theory in practice

Sub-Threshold

Region

VThreshold (VT)

MOSFET Two BasicRegions of Operation

ID

Drain

ID

Above

(Super)

Threshold

Gate

VGS

Source


Bridging theory in practice

ID

VDS = VGS - VT

VDS

MOSFET Super Threshold Regions of Operation

Linear Region

Drain

VGS = 5V

Saturation Region

ID

VGS = 4V

Gate

VGS = 3V

VGS = 2V

VGS = 1V

Sub-threshold

Region

VGS = 0V

Source


Bridging theory in practice

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

  • Moore’s Law


Bridging theory in practice

ID

VDS

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


Bridging theory in practice

ID

VDS

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


Bridging theory in practice

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

  • Moore’s Law


Mosfet equations and models

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


Mosfet square law model

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


Bridging theory in practice

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

  • Moore’s Law


Bridging theory in practice

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


Bridging theory in practice

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


Bridging theory in practice

Complementary MOSFET “CMOS” Inverter

5V

In

Out

0V


Bridging theory in practice

Complementary MOSFET “CMOS” Inverter

5V

In = 0V

Out

0V


Bridging theory in practice

Complementary MOSFET “CMOS” Inverter

5V

In = 0V

Out

With VGate = 0V,

a nMOS transistor

does not form

a channel

0V


Bridging theory in practice

Complementary MOSFET “CMOS” Inverter

5V

In = 0V

Out

With VGate = 0V,

a nMOS transistor

does not form

a channel

Switch OFF

0V


Bridging theory in practice

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


Bridging theory in practice

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


Bridging theory in practice

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


Bridging theory in practice

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


Bridging theory in practice

5V

In = 5V

Out

0V

Complementary MOSFET “CMOS” Inverter


Bridging theory in practice

Complementary MOSFET “CMOS” Inverter

5V

With VGate = 5V,

a pMOS transistor

does not form a

channel

In = 5V

Out

0V


Bridging theory in practice

Complementary MOSFET “CMOS” Inverter

5V

With VGate = 5V,

a pMOS transistor

does not form a channel

Switch OFF

In = 5V

Out

0V


Bridging theory in practice

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


Bridging theory in practice

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


Bridging theory in practice

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


Bridging theory in practice

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


Bridging theory in practice

5V

In

Out

0V

Complementary MOSFET “CMOS” Inverter

In

0V

5V

Out

5V

0V

NMOS

Off

On

PMOS

On

Off


Cmos inverter worst 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

CMOS InverterWorst Case Analysis


Bridging theory in practice

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

  • Moore’s Law


Integrated circuits

Integrated Circuits

Multiple devices can be placed on a single semiconductor die

This allows the design and manufacture of integrated circuits

0V

Input

5V

Output

SiO2

p

p

n

n

n-well

p-type substrate


Bridging theory in practice

Parasitic Resistances and Capacitances

Source

Gate

Drain

SiO2

n

n

p-type


Parasitic resistances and capacitances

Parasitic Resistances and Capacitances

Rco

Rco

Rac

Rac

Rsp

Rsp

Rsh

Rsh

Source

Gate

Drain

Rg

Rd

Rs

Cdo

Cdo

SiO2

Cg

Cif

Cif

Cof

Cof

Cd

n

n

Cj

Cj

p-type


Bridging theory in practice

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

  • Moore’s Law


Bridging theory in practice

Moore’s 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.”


Bridging theory in practice

Moore’s 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


Bridging theory in practice

Moore’s 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.”


Bridging theory in practice

Moore’s 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


Bridging theory in practice

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

  • Moore’s Law


Bridging theory in practice

Transistors andIntegrated Circuits


Chart slide

Chart Slide


End slide

End Slide


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