Skip to main content

Transistor

Introduction:


A transistor is a semiconductor device which is used to amplify the signals as well as in switching circuits. Generally, it consists of three terminals emitter(E), base(B) and collector(C) and two P-N junctions. It is one of the active components.

It was invented by John Bardeen, William Shockley and Walter Brattain in 1948, in Bell Telephone Laboratories.

Transistors are divided into different types depending on their construction and operation.
screenshot-30

Transistors are basically classified into two types; they are Bipolar Junction Transistors (BJT) and Field Effect Transistors (FET). The BJTs are again classified into NPN and PNP transistors. The FET transistors are classified into JFET and MOSFET. Junction FET transistors are classified into N-channel JFET and P-channel JFET depending on their function. MOSFET transistors are classified into Depletion mode and Enhancement mode. Again depletion and enhancement mode transistors are classified into N-channel JFET and P-channel.

depending on their function some other transistors are also available.

  • Small signal transistors

  • Small switching transistors

  • Power transistor

  • High frequency transistor

  • Photo transistor

  • Uni junction transistor


comparison of BJT and FET:


screenshot-29
Labels:

Comments

  1. BJT (bipolar junction transistor) | THE JARGONSeptember 24, 2016 at 3:54 PM

    […] bipolar junction transistor is a three terminal semiconductor current controlled device with two P-N junctions. The three […]

    ReplyDelete
  2. THE JARGONJune 10, 2017 at 3:52 AM

    […] →2.2 Transistors […]

    ReplyDelete

Post a Comment

Popular posts from this blog

Tellegens Theorem

Tellegen theorem states that  the summation of instantaneous powers for the n number of branches in an electrical network is zero. Suppose n number of branches in an electrical network have i 1 , i 2 , i 3 , .............i n respective instantaneous currents through them. These currents satisfy Kirchhoff's Current Law . Again, suppose these branches have instantaneous voltages across them are v 1 , v 2 , v 3 , ........... v n respectively. If these voltages across these elements satisfy Kirchhoff Voltage Law then,
1 comment
Read more

relay

A relay is an electrically operated switch. These are remote control electrical switches that are controlled by another switch. A relay is used to isolate one electrical circuit from another. It allows a low current control circuit to make or break an electrically isolated high current circuit path. The basic relay consists of a coil and a set of contacts. The most common relay coil is a length of magnet wire wrapped around a metal core. When voltage is applied to the coil, current passes through the wire and creates a magnetic field. This magnetic field pulls the contacts together and holds them there until the current flow in the coil has stopped. The diagram below shows the parts of a simple relay. Operation: When a current flows through the coil, the resulting magnetic field attracts an armature that is mechanically linked to a moving contact. The movement either makes or breaks a connection with a fixed contact. When the current is switched off, the armature is usually returned by...
1 comment
Read more

P-type semiconductor

The extrinsic  p Type Semiconductor  is formed, when a  trivalent impurity  is added to a pure silicon or germanium atom in small amount and as result large number of holes are created in it. A trivalent impurity like boron, aluminium, nitrogen, gallium, indium. have having three valence electrons but silicon or germanium have four valance electrons. so, it forms only three covalent bonds. In the   fourth covalent bond , only the germanium atom contributes one valence electron, while boron atom has no valence bonds. Hence, the fourth covalent bond is incomplete, having one electron short. This missing electron is known as a  Hole . Thus, each boron atom provides one hole in the germanium crystal. As an extremely small amount of boron impurity has a large number of atoms, therefore, it provides millions of holes in the semiconductor.
Post a Comment
Read more