The Jargon

A bipolar junction transistor is a three terminal semiconductor current controlled device with two P-N junctions. The three terminals are emitter(E), base(B) and collector(C). the emitter junction is heavily doped, base is less doped and made very thin and collector terminal is moderately doped. Collector has grater size than emitter and base terminal is thinner than both. (The thinner the base, the stronger the E-C electric field, and the larger the impact of a small current injected into the base. Explained clearly in active mode operation below) emitter terminal is moderate in size. A BJT has two types of transistors: NPN transistor PNP transistor NPN transistor : In an NPN transistor a p-type material is sandwiched between two n-type materials. [gallery ids="979,978" type="rectangular"] PNP transistor : In a PNP transistor a n-type material is sandwiched between two p-type materials. [gallery ids="989,990" type="rectangular"] Oper...

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. 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. d...

Introduction : A photo diode is a semi-conductor device, with a p-n junction and an intrinsic layer between p and n layers. It can be used as a light detector, which involves the conversion of light into current or voltage depending on mode of operation. [gallery ids="867,866" type="rectangular"] construction :   Working : When a photon of sufficient energy strikes the diode, it creates an electron-hole pair. This mechanism is also known as the inner photoelectric effect. If it occurs at the junction these carriers are swept from the junction by the built-in electric field of the depletion region. Thus holes move toward the anode, and electrons toward the cathode, and a photo current is produced. The total current through the photo diode is the sum of the dark current (current that is generated in the absence of light) and the photo current, so the dark current must be minimized to maximize the sensitivity of the device. Mainly it is operated in two modes 1.  Photo ...

introduction : A tunnel diode is a highly doped semiconductor device that conducts current by quantum mechanical tunneling. it is also called as esaki diode named after leo esaki who got Nobel  prize in physics for discovering electron tunneling in 1973. Tunneling  Phenomenon: According to classical laws of physics, a particle must have an energy at least equal to the height of a potential-energy barrier if it has to move from one side of the barrier to the other. In other words, energy has to be supplied from some external source so that the electrons on one side of junction climb over the junction barrier to reach the other side. However if the barrier is thin such as in tunnel diode, the Schrodinger equation(Quantum Mechanics) indicates that there is a large probability that an electron will penetrate through the barrier. This will happen without any loss of energy on the part of electron. This quantum mechanical behavior is referred to as tunneling and the high-impurity P-N junctio...

introduction: schottky diode is named after named after German physicist Walter H. Schottky.  it is also called as hot carrier diode or surface barrier diode. [caption id="attachment_729" align="aligncenter" width="289"] symbol of schottky diode[/caption] construction : In P-N junction diode semiconductor(P-type)-semiconductor(N-type) junction is formed but, in the case of schottky diode metal-semiconductor junction is formed. basically metals used are molybdenum, platinum, chromium, tungsten Aluminium, gold e.t.c and the semiconductor used is N type silico n is used. working : Schottky diode is often referred as “majority carrier diode”.. When materials are joined, electrons in n-type silicon immediately flow into metal because the electrons in semi conductor are at higher energy level than metal and hence electron flow is established. The flow of electrons stops when Fermi level of two materials are at same level. Due to flow of electrons into m...

Half wave rectifier: Full wave rectifier: with filter across output terminals : Capacitor blocks dc signal and allows ac signal through it. here same thing works capacitor short circuits ac signal.    

Introduction : Zener diodes are a special type of semiconductor diode which is operated in reverse bias.it conducts current in bot forward and reverse bias. this device is named after clarance Melvin zener who discovered zener effect. In forward bias it will act as normal P-N junction diode and it will not turn till more than 0.7 volts are provided.  when it is operated in reverse bias it will allow small amount of current till reverse voltage reaches Zener voltage. If you increase reverse voltage beyond Zener voltage (vz) leakage current increases. It is called Zener break down or zener effect and this voltage is called breakdown voltage. Break down mechanisms are two type 1.  Avalenche break down.  2.Zener break down Avalanche breakdown : A P-type semiconductor in contact with an N-type semiconductor forms a depletion region when it is operated in reverse bias, as bias voltage increases width of this depletion region also increases. In reverse bias condition very little amount o...