BJT - Bipolar Junction Transistor

1904 to 1947

Vacuum tube was the electronic device of interest and development

1904

Vacuum tube diode was introduce by _________

J. A. Fleming

Introduce Vacuum tube diode in _______

1906

_______ added third element called control grid to the vacuum diode, resulting in the first amplifier the triode.

Lee De Forest

Added the third element called control grid to the vacuum diode, resulting in the first amplifier, the triode.

December 23, 1947

Demonstration of the amplifying action of the first transistor at the Bell Telephone Labortatories

Dr. S. William Shockley, Walter H. Brattain, & John Bardeen

The inventors of the first transistor, demonstrating its functionality at Bell Labs.

• Smaller & Lightweight

• No heater requirement

• Rugged Construction

• Less power absorbed

• No Warm-up Period

• Low Voltage use

Advantages of Transistors.

Transistor

A three-layer semiconductor device consisting of either two n and p-type material.

DC Biasing

Necessary to establish the proper region of operation for ac amplification. Emitter layer is heavily doped, with the base and collector only lightly doped.

Doping

The process of adding impurities to a semiconductor to change its electrical properties, enhancing conductivity. Also considerably less than that of the outer layers. Decreases conductivity (increases resistance)