Post on 28-Mar-2015
transcript
ME 6405 Student Lecture
Transistor
Sung-bum Kang
Keun Jae Kim Hongchul Sohn
Wenwei Xu
October 1, 2009
Georgia Institute of Technology
Contents
Introduction to Transistor(Speaker: Sung-bum Kang)
Field Effect Transistor(Speaker: Hongchul Sohn)
Power Transistor(Speaker: Wenwei Xu)
11
33
44
Applications of Transistor(Speaker: Wenwei Xu)55
Bipolar Junction Transistor(Speaker: Keun Jae Kim)22
“Transistor” Part 1
Introduction to Transistor(Speaker: Sung-bum Kang)11
Field Effect Transistor(Speaker: Hongchul Sohn)
Power Transistor(Speaker: Wenwei Xu)
33
44
Applications of Transistor(Speaker: Wenwei Xu)55
Bipolar Junction Transistor(Speaker: Keun Jae Kim)22
Introduction
Question #1: How can we transfer original signal in long distance without loss?
Amplifier and Electronic Switch are needed.
Amplifier: any device that changes, usually increases, the amplitude of a signal. Electronic Switch: switch that the physical opening and closing is achieved by
applying appropriate electrical control signals.
Question #2: How can we control the TV with remote-controller?
Question #3: How can a computer recognize 0(off) and 1(on) for computing?
Introduction
Early 20th century, vacuum tube was used for the amplifier and switch.
ENIAC, the first general-purpose electronic
computer, contains 17,468 vacuum tubes.Vacuum Tube Radio
However, Vacuum Tube is too big, fragile, and energy-consuming.
Transistor solved this problem.
Introduction – Invention of Transistor
Invention In 1947, John Bardeen, Walter Brattain,
and William Schockly, researchers at Bell Lab, invented Transistor.
They found Transistor Effect: “when electrical contacts were applied to a crystal of germanium, the output power was larger than the input.”
In 1956, they were awarded the Nobel Prize in physics.
Transistor is a semiconductor device commonly
used to amplify or switch electronic signals.
John Bardeen, Walter Brattain,
and William Schockly
First model of Transistor, 1947
Introduction – Progress of Transistor
more than 2.9 billion transistors is packed into an area of fingernail
1941, Vacuum Tube
1948, the first (Germanium) TR
1954, Silicon TR
1958, Integrated Circuit
Sep 2009, 22nm silicon wafer
Now?
Edison effect
John Bardeen, Walter Brattain, and William Schockly
At TI Lab, Ease of processing, lower cost, greater power handling, more stable temperature characteristics
Intel CEO Paul Otellini, Sep 23 2009
Individual electronic components were soldered on to printed circuit boards.
IC placed all components in one chip.
Introduction – Underlying Science
Semiconductor is a basic building material of most integrated circuits. is a material that has an electrical resistivity between that of a
conductor and an insulator. has a few charge carriers(holes or free electrons) and may hence
be classified as almost insulator. However, the conductivity increases by adding impurities(doping).
Silicon is used in most commercial
semiconductors
Introduction – Underlying Science
Doping P(positive)-type doping is adding a certain type of atoms to the
semiconductor in order to increase holes. P-type semiconductor, acceptor
N(negative)-type doping is adding some amount of an element with more electrons in order to increase free electrons.
N-type semiconductor, donor
Add Group III(Boron)Add Group V (Phosphorous)
Introduction – Underlying Science
PN Junction is a junction formed by P-type and
N-type semiconductors together in very close contact.
Electrons(+) from n(-) region diffuse to occupy holes(-) in p(+) region.
Thin depletion region forms near junction.
What happens at the junction?
Introduction – Underlying Science
Forward bias -V pumps electrons into the N-region. +V pumps more holes into the P-region. Excess of charge in P and N region will
apply pressure on the depletion region and will make it shrink.
→ current flows
Backward bias -V sucked out electrons from N-region. +V sucked out holes from P-region. The depletion layer widens and it
occupies the entire diode(p-n). → current doesn’t flow
External Energy
Introduction – Types of Transistor
Transistor are categorized by Semiconductor material: germanium, silicon, gallium arsenide, etc.
Structure: BJT, FET, IGFET (MOSFET), IGBT
Polarity: NPN, PNP (BJTs); N-channel, P-channel (FETs)
Maximum power rating: low, medium, high
Maximum operating frequency: low, medium, high
Application: switch, audio, high voltage, etc.
Physical packaging: through hole, surface mount, ball grid array, etc.
Amplification factor Various Types of Transistor:
http://en.wikipedia.org/wiki/Category:Transistor_types
General Purpose Transistors Bipolar Junction Transistor (BJT) Field Effect Transistors (FET) Power Transistors
“Transistor” Part 2
Field Effect Transistor(Speaker: Hongchul Sohn)
Power Transistor(Speaker: Wenwei Xu)
33
44
Applications of Transistor(Speaker: Wenwei Xu)55
Bipolar Junction Transistor(Speaker: Keun Jae Kim)
Introduction to Transistor(Speaker: Sung-bum Kang)11
22
BJT Introduction
PNP
NPN 3 Terminals
Base (B) Collector (C) Emitter (E)
2 Types: NPN, PNP Currents flow in opposite
direction NPN:
BE forward biased BC reverse biased
PNP: BE reverse biased BC forward biased
Georgia Institute of Technology 15
BJT Characteristics
IC is controlled by IB (Current Control) β (beta) is amplification factor for
transistor Typical value of is β 20 ~ 200
iE = iC + iB iC = βiB
VBE = VB – VE
VCE = VC - VE
Operating Regions
BJT Operating Regions
Operating Regions
Operating Region
Parameters Mode
Cut OffVBE < Vcut-in VCE > Vsupply
IB = IC = 0Switch OFF
LinearVBE = Vcut-in
Vsat < VCE < Vsupply
IC = β*IB
Amplification
Saturated
VBE = Vcut-in,VCE < Vsat
IB > IC,max, IC,max > 0
Switch ON
BJT Operating Regions
Georgia Institute of Technology 18
1) Cutoff Region: VBE < Vcut-in, iB = 0 iC = 0, VCE > Vsupply
2) Active / Linear Region: VBE = Vcut-in, iB > 0 iC = βiB, Vsat < VCE < Vsupply
3) Saturation Region: VBE = Vcut-in, iB > iC,max iC,max, VCE < Vsat
Vin
Vsupply
BJT Operating Regions
VSupplyVin
RB
RC
Question: What is the minimum Vin that can use the transistor as an amplifier?
Given:• RB = 10 kΩ• RC = 1 kΩ • β = 100• VSupply = 10 V• Vcut-in = 0.7 V• Vsat = 0.2 V
iB = iC / β = 0.0098/100 = 0.098mA
BJT as Amplifier
Vin - iB*RB – VBE = 0
Vsupply – iC *RC – VCE=0
iC = (Vsupply – VCE) / RC
Set VCE = Vsat = 0.2V
iC = (10 – 0.2) / 1000 = 9.8mA
iC = βiB
Vin = iB*RB + VBE
Set VBE = Vcut-in = 0.7V
Vin = 0.098*(10-3)*10000 + 0.7V
Vin = 1.68V or greater.
From
3rd Exercise
Turns on/off coils digitally
BJT as Switch
44
55
22
33
11 Introduction to Transistor(Speaker: Sung-bum Kang)
Field Effect Transistor(Speaker: Hongchul Sohn)
Power Transistor(Speaker: Wenwei Xu)
Applications of Transistor(Speaker: Wenwei Xu)
Bipolar Junction Transistor(Speaker: Keun Jae Kim)
“Transistor” Part 3
Field-Effect Transistors
Basics Conduction of a “channel” is controlled by electric field effect
Three terminals: gate, source, drain
Voltage-controlled current device
control terminal
current channel
of charge carriers for charge carriers
control voltage
Very little current flows through input (gate) terminals
Field-Effect Transistors
BJT vs. FET What was BJT then?
A current-controlled current device
Comparison
Field-Effect Transistors
Types JFET (Junction FET)
MOSFET (Metal-oxide-semiconductor FET)
MESFET (Metal-semiconductor FET)
HFET (Hetero-structure FET)
MODFET (Modulation doped FET)
IGBT (Insulated-gate bipolar transistor)
Power MOSFETs
FREDFET (Fast reverse or fast recovery epitaxial diode FET)
ISFET (Ion-sensitive FET)
DNAFET
JFET (Junction FET)
MOSFET (Metal-oxide-semiconductor FET)
JFETs
JFETs n-channel
General Properties Advantages: Much higher input resistance, lower noise, easier
fabrication, ability to handle higher currents and powers
Disadvantages: Slower speeds in switching circuits, smaller bandwidth for a given gain in an amplifier
p-channel
n-channel JFET
Characteristics
n-channel JFET
Characteristics Idealized Static
2(1 )GSD DSS
P
vi I
V
n-channel JFET
Characteristics Practical Static
2(1 ) (1 )GS DSD DSS
P A
v vi I
V V
Transfer
MOSFETs
MOSFETs or Insulated-gate FET (IGFET)
n-channel Enhancement
General Properties Input resistance even higher
Used primarily in digital electronic circuits
Provide controlled-source characteristics in amplifier circuits
n-channel Depletion
n-channel Enhancement MOSFET
Characteristics
n-channel Enhancement MOSFET
Characteristics Practical
2( ) (1 )DSD GS T
A
vi K v V
V 2[2( ) ]D GS T DS DSi K v V v v
n-channel Depletion MOSFET
Characteristics Practical
2[2(1 )( ) ( ) ]GS DS DSD DSS
P P P
v v vi I
V V V 2(1 ) (1 )GS DS
D DSSP A
v vi I
V V
Task: Design a n-channel common-source JFET Amplifier
Amplifiers, Switches
Applications
You CAN do it!! Psst! You can read it!!http://www.electronics-tutorials.ws/amplifier/amp_3.html
“Transistor” Part 4
Introduction to Transistor(Speaker: Sung-bum Kang)
Field Effect Transistor(Speaker: Hongchul Sohn)
Power Transistor(Speaker: Wenwei Xu)
11
33
Applications of Transistor(Speaker: Wenwei Xu)
Bipolar Junction Transistor(Speaker: Keun Jae Kim)22
44
55
Power Transistor
Concerned with delivering high power Used in high voltage and high current application
In generalFabrication process different in order to: Dissipate more heat Avoid breakdownLower gain than signal level transistor
Power BJT
Same structure to the signal level BJT The active area is distinctively higher-high current
capacity Thick and low-doped collector region Large heat dissipation--- larger dimensions
Power MOSFET
Same working principles to MOSFET
Designed to handle large power
Low internal voltage drop and high current capacity
High commutation speed and good efficiency at low voltages—high speed switch
Applications of Transistorbuilding blocks for modern electronics
Digital logic circuits Microprocessors, microcontrollers, chips (TTL) Photo-transistors Replaces normal switches, mechanical relays. A/D converter Encoders Multiplexers Power supplies
more…
microprocessorwireless
communicationmotor
headphone, microphone
Applications(cont.)
– Switch for a digital signal: BJT or MOSFET – Switch for a analog signal: JFET – Switch for a power signal: Power MOSFET or BJT – Current controlled-current amplifier: BJT – Voltage controlled-current amplifier: JFET or MOSFET
Small input voltage and large output currentoperated in the cut-off region(open) and saturation region(close)
Example: 2N3904 NPNAssuming LED requires 20-40 mA to provide a bright display and has 2 voltage drop when forwarded biased
Output=0V—offOutput=5V---on, the transistor is in saturation, with base current
(5 0.7 ) /10 0.43BI V V K mA
Collector current (LED current) is limited by collector resistor
mAVVVIC 28100/)2.025(
BJT as switches
BJT as amplifiers
Audio amplifiers, radio frequency amplifiers, regulated power supplies
Low input impedance and high voltage gain
ExampleSpeaker amplifier
BJT series produce higher gain
Applications of FET
Advantages of FET over BJT They are devices controlled by voltage with a very high input
impedance (107 to 1012 ohms) FETs generate a lower noise level than the Bipolar Junction
Transistor (BJT) FETs are more stable than BJT with temperature FETs are easier to manufacture than the BJT, because they require
fewer steps to be built and they allow more integrated devices in the same IC
FETs behave like resistors controlled by voltage for small drain-source voltage values
The high input impedance of FET allows them to withhold loads long enough to allow its usage as storage elements
Power FETs can dissipate higher power and can switch very large currents.
Applications of FET
Amplifiers•Small Signal•Low Distortion•High Gain•Low Noise amplifier•Selectivity•High-Frequency
Switches•Chopper-Type•Analog Gate•Communicator
Protection Diodes•Low-leakage
Current LimitersResistorsMixersOscillators
FET as analog switch-example
When VGS = 0, FET becomes saturated and it behaves like a small resistance(<100 ohm) and, therefore,
VOUT = {RDS/ (RD + RDS (ON))}* Vin
RD>>RDS, VOUT → 0
When a negative voltage equal to VGS (OFF) is applied to the gate, the FET operates in the cut-off region and it acts like a very high resistance usually of some mega ohms. Hence output voltage becomes nearly equal to input voltage.
Contact information(in order of presenting)
Sung-bum Kang sb.kang@gatech.edu Keun Jae Kim kkim345@gatech.edu Hongchul Sohn hsohn7@gatech.edu Wenwei Xu xuw3@gatech.edu
References www.wikipedia.org www.google.com
“Introduction to Electrical Engineering”, Mulukata S. Sarma, Oxford University Press, 2001, Chap. 7.4~8.4. Fall 2008 Transistors Slides http://www-g.eng.cam.ac.uk/mmg/teaching/linearcircuits/index.html http://en.wikipedia.org/wiki/FET http://en.wikipedia.org/wiki/JFET http://en.wikipedia.org/wiki/MOSFET http://www.slideshare.net/guest3b5d8a/fets “Introduction to Electrical Engineering”, Mulukata S. Sarma, Oxford University Press, 2001, Chap. 7.4~8.4. Fall 2008 Transistors Slides http://www-g.eng.cam.ac.uk/mmg/teaching/linearcircuits/index.html http://en.wikipedia.org/wiki/FET http://en.wikipedia.org/wiki/JFET http://en.wikipedia.org/wiki/MOSFET http://www.slideshare.net/guest3b5d8a/fets
http://www.electronics.dit.ie/staff/ypanarin/Lecture%20Notes/K235-1/2%20Transistor-Thyristor.pdf http://ecee.colorado.edu/~bart/book/book/chapter5/ch5_9.htm http://www.ece.mtu.edu/labs/EElabs/EE3305/Bipolar_Junction_Transistors.pdf http://www.partminer.com/glossaryhtml/bjt.htm http://www.lycos.com/info/bipolar-junction-transistor--applications.html http://jimwarholic.com/uploaded_images/power-supply-768753.jpg http://abbydamico.files.wordpress.com/2008/09/microprocessor-athlon-64.jpg http://www.billfrymire.com/blog/wp-content/uploads/2008/05/wireless-communication-connection-1000.jpg http://www.cybermediatech.com/images/WirelessHeadphone-big.jpg http://www.colorado.edu/physics/phys3330/phys3330_fa09/pdfdocs/AN101FETintro.pdf http://www.circuitstoday.com/fet-applications
Thank you!