Bipolar Junction Transistors

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Bipolar Junction Transistors

• (INTRODUCTION)

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TRANSISTORS

• The name transistor is derived from transfer
  resistor , indicating a solid-state device.
  Instead of depending on thermal emission, the
  solid semiconductor has free charges that are
  controlled by the input voltage to provide
  rectification or amplification in the output.
  Since there is no heated filament, the operation
  of semiconductor devices is instantaneous,
  without any warm-up time.

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• 1904-1947
• vacuum tube was the electronic device of interest
  and development
• 1904
• vacuum tube diode was introduced by J.A.
  Fleming.
• 1906
• Lee De Forest added a third element, the control
  grid to the vacuum diode resulting in the first
  amplifier, the triode.

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• In the following years, the production rose from
  about 1 million tubes in 1922 to about 100
  million in 1937 because of radio and television.
• The industry became one of the primary importance
  and rapid advances were made in design,
  manufacturing techniques, high-power and
  high-frequency applications and miniaturization.

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December 23, 1947

• Walter H. Brattain and John Bardeen demonstrated
  the amplifying action of the First Transistor (a
  point-contact transistor) at the Bell Telephone
  Laboratories.

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Advantages of the transistor over the tube

• smaller and lightweight
• no heater required and heater loss
• rugged construction
• more efficient since less-power was absorbed by
  the device itself
• instantly available for use (no warm-up period)
• Lower operating voltages were possible

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The Inventors

• Dr. Shockley
• - was born in London England on 1910
• - PhD in Harvard in 1936
• Dr. Bardeen
• -was born in Madison, Wisconsin on 1908
• -PhD in Princeton in 1936
• Dr. Brattain
• -was born in Amoy, China on 1902
• -PhD in University of Minessota in 1928

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