Transistor - Wikipedia, the free encyclopedia

Transistor - Wikipedia, the free encyclopedia - Transistor...

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 Transistor From Wikipedia, the free encyclopedia Jump to: navigation , search Assorted discrete transistors In electronics , a transistor is a semiconductor device commonly used to amplify or switch electronic signals. A transistor is made of a solid piece of a semiconductor material, with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current flowing through another pair of terminals. Because the controlled current can be much larger than the controlling current, the transistor provides amplification of a signal. The transistor is the fundamental building block of modern electronic devices , and is used in radio , telephone , computer and other electronic systems. Some transistors are packaged individually but most are found in integrated circuits .
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Contents 1 Introdu ction 2 History 3 Importa nce 4 Usage 4 . 1 S w i t c h e s 4 . 2 A m p l i f i e r s 4 . 3 C o m p u t e r
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[ edit ] Introduction An electrical signal can be amplified by using a device that allows a small current or voltage to control the flow of a much larger current. Transistors are the basic devices providing control of this kind. Modern transistors are divided into two main categories: bipolar junction transistors (BJTs) and field effect transistors (FETs). Applying current in BJTs and voltage in FETs between the input and common terminals increases the conductivity between the common and output terminals, thereby controlling current flow between them. The characteristics of a transistor depend on its type. The term "transistor" originally referred to the point contact type, which saw very limited commercial application, being replaced by the much more practical bipolar junction types in the early 1950s. Today's most widely used schematic symbol , like the term "transistor", originally referred to these long-obsolete devices. [1] In analog circuits , transistors are used in amplifiers , (direct current amplifiers, audio amplifiers, radio frequency amplifiers), and linear regulated power supplies . Transistors are also used in digital circuits where they function as electronic switches, but rarely as discrete devices , almost always being incorporated in monolithic integrated circuits . Digital circuits include logic gates , random access memory (RAM), microprocessors , and digital signal processors (DSPs). [ edit ] History Main article: History of the transistor A replica of the first working transistor. The first patent [2] for the field-effect transistor principle was filed in Canada by Austrian-Hungarian physicist Julius Edgar Lilienfeld on October 22, 1925, but Lilienfeld did not publish any research articles about his devices. [3] In 1934 German physicist Dr. Oskar Heil patented another field-effect transistor. There is no direct evidence that these devices were built, but later work in the 1990s shows that one of Lilienfeld's designs worked as described and gave substantial gain. Legal papers from the Bell Labs patent show that
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This note was uploaded on 09/29/2010 for the course GENERAL AR ECE 250 taught by Professor Drcapps during the Spring '10 term at N.C. State.

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Transistor - Wikipedia, the free encyclopedia - Transistor...

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