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A bipolar junction transistor (BJT) is a type of transistor that uses both electrons and electron holes as charge carriers. In contrast, a unipolar transistor, such as a field-effect transistor (FET), uses only one kind of charge carrier.
The introduction of the transistor is often considered one of the most important inventions in history. [1] [2] Transistors are broadly classified into two categories: bipolar junction transistor (BJT) and field-effect transistor (FET). [3] The principle of a field-effect transistor was proposed by Julius Edgar Lilienfeld in 1925. [4]
The first bipolar junction transistors were invented by Bell Labs' William Shockley, who applied for patent (2,569,347) on June 26, 1948. On April 12, 1950, Bell Labs chemists Gordon Teal and Morgan Sparks successfully produced a working bipolar NPN junction amplifying germanium transistor. Bell announced the discovery of this new "sandwich ...
This seminal work became the reference text for other scientists working to develop and improve new variants of the transistor and other devices based on semiconductors. [34] This resulted in his invention of the bipolar "junction transistor", which was announced at a press conference on July 4, 1951. [35]
The bipolar point-contact transistor was invented in December 1947 [9] at the Bell Telephone Laboratories by John Bardeen and Walter Brattain under the direction of William Shockley. The junction version known as the bipolar junction transistor (BJT), invented by Shockley in 1948. [10]
A heterojunction bipolar transistor (HBT) is a type of bipolar junction transistor (BJT) that uses different semiconductor materials for the emitter and base regions, creating a heterojunction. The HBT improves on the BJT in that it can handle signals of very high frequencies, up to several hundred GHz .
An NPN grown-junction transistor with the cover removed to show the germanium ingot and the base wire. The grown-junction transistor was the first type of bipolar junction transistor made. [1] It was invented by William Shockley at Bell Labs on June 23, 1948 [2] (patent filed June 26, 1948), six months after the first bipolar point-contact ...
BC548 transistor. The BC548 is a general-purpose NPN bipolar junction transistor commonly used in European and American electronic equipment. It is notably often the first type of bipolar transistor hobbyists encounter and is often featured in designs in hobby electronics magazines where a general-purpose transistor is required.