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  1. 1. Transistors • History • Transistor Types • BJT: A bipolar (junction) transistor is a threeterminal electronic device constructed of doped semiconductor material and may be used in amplifying or switching applications • FET :The field-effect transistor (FET) relies on an electric field to control the shape and hence the conductivity of a channel of one type of charge carrier in a semiconductor material • Power transistors
  2. 2. What is a Transistor? A Transistor is an electronic device composed of layers of a semiconductor material which regulates current or voltage flow and acts as a switch or gate for electronic circuit.
  3. 3. History of the Transistor John Pierce –supervised the Bell Labs team which built the first transistor (1947) First Solid State Transistor – (1951) Gordon K. Teal (left) and Morgan Sparks at Bell Laboratories, 1951 Akio Morita, who founded a new company named Sony Electronics that mass-produced tiny transistorized radios (1961)
  4. 4. Processor development followed Moore’s Law
  5. 5. Applications Switching Amplification Oscillating Circuits Sensors
  6. 6. Composed of N and P-type Semiconductors • N-type Semiconductor has an excess of electrons – Doped with impurity with more valence electrons than silicon P-type Semiconductor has a deficit of electrons (Holes) – Doped with impurity with less valence electrons than silicon
  7. 7. P-N Junction (Basic diode): - Bringing P and N Semiconductors in contact P Type N Type - Creation of a Depletion Zone
  8. 8. Reverse Biased => No Current Applying –Voltage to Anode increases Barrier Voltage & Inhibits Current Flow Forward Biased => Current • Applying Voltage to Cathode • Barrier Voltage to Anode allows current flow
  9. 9. Types Of Transistors NPN: transistor where the majority current carriers are electrons The majority current carriers in the PNP transistor are holes
  10. 10. Transistor Operation
  11. 11. California Test Questions A transistor circuit is used as an amplifier. When a signal is applied to the input of the transistor, the output signal is     A a smaller amplitude. B an equal amplitude. C a larger amplitude. D zero amplitude. C: The collector and emitter will amplify the output signal from the Bias input.
  12. 12. California Test Questions A transistor is classified as a semiconductor because:     A the transistor conducts electricity. B the transistor increases the amplitude. C the transistor increases the frequency. D intentionally introducing impurities into an extremely pure silicon or germanium. D intentionally introducing impurities into an extremely pure silicon or germanium. 
  13. 13. Summary Transistors are composed of three parts – a base, a collector, and an emitter . Semi-conductive materials are what make the transistor possible . There are two main types of transistors-junction transistors and field effect transistors. Field effect transistor has only two layers of semiconductor material, one on top of the other