Transistors Basic Concept
•Download as PPT, PDF•
1 like•135 views
Transistor Definition,Circuit,Classification & Application.
Recommended
More Related Content
What's hot
What's hot (19)
Similar to Transistors Basic Concept
Similar to Transistors Basic Concept (20)
Recently uploaded
Recently uploaded (20)
Transistors Basic Concept
- 1. Justin Chow Jacob Huang Daniel Soledad ME 4447/6405 Student Lecture
- 2. History Properties Types BJT JFET MOSFET Applications Overview Daniel Soledad
- 3. Transistor History “Transistor” is combination of “transconductance” and “variable resistor” HowTransistors Are Made ▪ Vacuum tubes ▪ Inefficient, fragile, bulky, generated a lot of heat ▪ FirstTransistors ▪ Semiconductors – Bell Labs 1947 Introduction
- 4. Packaging Surface Mount orThrough Hole Usually 3 or 4 terminal device ▪ Can be packaged into ICs GeneralApplications Amplification/Regulation Switches Introduction
- 5. Current Controlled i.e: BJT The output current is proportional to input current Voltage Controlled i.e.: JFET, MOSFET The output current is proportional to input voltage
- 6. Bipolar JunctionTransistor 3 semiconductor layers sandwiched together Comes in two flavors NPN BJT PNP BJT BJT Transistor Justin Chow
- 7. Diodes Forward Biased Reverse Biased current flows no current flows whenVPN > .6-.7V BJT Transistor
- 8. BJT Basics (NPN) BE Forward Biased BC Reversed Biased β=IB / Ic ≈ 100 IE = IB + IC BJT Transistor emitter base collector Electron Flow
- 9. Things to remember PNP, biasing opposite Conventional current vs electron flow A small input current controls a much larger output current. BJT Transistor
- 10. Operating Regions BJT Transistor Operating Region Parameters Cut Off VBE <0.7V IB = IC = 0 Linear VBE >0.7V IC = β*IB Saturated IB > 0, IC > 0 VBE >0.7V, VCE 0.2V
- 11. Operating Regions BJT Transistor
- 12. From 3rd Exercise Turns on/off coils digitally
- 13. Common Emitter Amplifier BJT Transistor β=100
- 14. Common Emitter Amplifier BJT Transistor IB = (Vin − VB) / 10000Ω = (Vin − 0.7) / 10000Ω IC = β(Vin − 0.7) / 10000Ω Vout=10000*(Vin-0.7)/1000 When VCE = 0.2V IC = 9.8 / 1000Ω = 9.8mA IB = IC / β = 0.098mA Vin − 0.7 = (0.098mA)(10000Ω) Vin = 1.68V or greater.
- 15. Power Dissipation PBJT =VCE * iCE Should be below the rated transistor power Important for heat dissipation as well BJT Transistor
- 16. Increased Gain β = β1 * β2 VBE =VBE1 +VBE2 Slower Switching 2N6282
- 17. Analogous to BJT Transistors Output is controlled by input voltage rather than by current 4 Pins vs. 3 BJT FET Collector Drain Base Gate Emitter Source N/A Body
- 18. FET (Field EffectTransistors) MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) JFET (Junction Field-EffectTransistor) MESFET HEMT MODFET Most common are the n-channel MOSFET or JFET Jacob Huang
- 19. In practice the body and source leads are almost always connected Most packages have these leads already connected B S G D B S G D S G D MOSFET JFET
- 20. Metal-Oxide Semiconductor F.E.T. A.K.A. Insulated-Gate FET (IGFET) 2 Modes: Enhancement/Depletion
- 21. N-Channel +Vgs -> More electrons -> More Current - Vgs -> Less electrons -> Less current P-Channel – Reversed Different from BJT
- 23. N-Channel VGS >Vth ->Turns on device VGS <VTH -> No Current P-Channel Reversed Only E-type used now
- 24. Region Criteria Effect on Current Cut-off VGS < Vth IDS=0 Linear VGS > Vth And VDS <VGS-Vth Transistor acts like a variable resistor, controlled by Vgs Saturation VGS > Vth And VDS >VGS-Vth Essentially constant current Current flow B S G D
- 26. Used in high-power applications Heat Sink Vertical layout Not Planar like other transistors
- 27. Reverse BiasVGS => Reduces channel size => Reduced Current Defaults “on”
- 28. Vgs = 0 “on” |Vgs|> |Vp| “off” Vp = Pinch-off or Cut-offVoltage
- 29. Internal Capacitance Bi-directional Cut-off voltage is varying for each JFET 0.3V – 10V N-Channel – NegativeVGS P-Channel – PositiveVGS Do not Forward Bias JFET – burn out
- 31. Property BJT MOSFET JFET Gm Best Worst Medium Speed High Medium Low Noise Moderate Worst Best Good Switch No Yes Yes High-Z Gate No Yes Yes ESD Sensitivity Less More Less
- 32. Complementary MOS Used in Logic Gates P-channel (PMOS) to high N-channel (NMOS) to low HIGH usually +5V LOW usually ground Q is high when A = 0, Q is low when A = 1