Transistor

James Malm

1

Essay on Transistor

The transistor is a virtually invisible electronic device that has changed the lives of many people. Before the invention of transistors, vacuum tubes were used to amplify electrical signals. The vacuum tubes consumed lots of power and they needed regular maintenance to clean and adjust. This made them very expensive. Scientists were therefore faced with the challenge to come up with a more reliable, cost effective device to replace the vacuum tubes. In 1947, the transistor was invented at the Bell Laboratories. The transistor has two basic functions: modulation and switching. Modulation is often used to achieve amplification of electrical signal. The transistor regulates current and voltage flow and acts as a switch for electronic signals. They are made from semiconductors such as Silicon and Germanium since these elements conduct electricity moderately well. The transistor consist of three layers of a semiconductor materials each capable of carrying current. The semiconductor material is given special properties by a chemical process called doping. The doping results in a material that either adds extra electrons to the materials (n-type) or creates extra holes (p-type) in the material crystal structure. A small change in the current or the voltage at the inner semiconductor layer which acts as the control electrode produces a large rapid change in the current passing through the entire component. The component can thus act as a switch, opening and closing an electronic gate many times in a second. Transistors are the basic elements in integrated circuits (ICs) consisting of very large number of transistors connected with circuitory and backed into a single silicon microchip or chip. It may take scores of transistors to accomplish a task as simple as adding one and one.