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

A P-N junction diode is a basic diode. It is the combination of P-type and N-type semiconductor. symbol : P-N junction and potential barrier : A P-N junction is the basic building block of many semiconductor devices like diodes and transistors. P -n  junctions are formed by joining  n -type and  p -type semiconductor materials. Since the  n -type region has a high electron concentration and the  p -type a high hole concentration this difference in concentration creates density mismatch across junction which results to creation of potential barrier. The value of potential barrier v b  is 0.3 for germanium and 0.7 for silicon. Working : Forward bias: Application of positive charge at p-side pushes holes towards potential barrier and similarly negative charge at N-side pushes electrons towards barrier if input voltage is grater than potential barrier then electrons diffuse from the  n -type side to the p-type side. Similarly, holes flow by diffusion from the p-type side to the n-type side

Frederick Guthrie invented the diode in 1873, but did not put it into practical use. Thomas Edison independently developed it in 1880, then used it in his 1883 patent of the incandescent light bulb. John Ambrose Fleming received the first patent on the diode itself in 1904. A Diode is a two terminal active component that conducts primarily in one direction. Diodes are one of the simplest, but most useful of all semiconductor devices. Many types of diode are used for a wide range of applications. Rectifier diodes are a vital component in power supplies where they are used to convert AC mains (line) voltage to DC. Zener diodes are used for voltage stabilization, preventing unwanted variations in DC supplies within a circuit. Signal diodes are used to obtain the audio and video signals from transmitted radio frequency signals (demodulation) and can also be used to shape and modify AC signal waveforms (clipping, limiting and DC restoration). Diodes are also built into many digital integra

The extrinsic  n Type Semiconductor  is formed, when a  pentavalent impurity  is added to a pure silicon or germanium atom in small amount and as result large number of electrons are created in it. A pentavalent impurity like phosphorous, arsenic, antimony, antimony, bismuth, lithium Antimony have having five valence electrons but, silicon or germanium need only four valance electrons. it forms four covalent bonds. But, one electron will be left excess in Antimony Thus, each Antimony atom leaves one excess electron in the germanium crystal. As an extremely small amount of Antimony impurity has a large number of atoms, therefore, it provides millions of electrons in the semiconductor. Energy band diagram :

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.

Introduction: A light-emitting diode (LED) is a semiconductor light source. LED's are used as indicator lamps in many devices, and are increasingly used for lighting. Introduced as a practical electronic component in 1962, early LED's emitted low-intensity red light, but modern versions are available across the visible, ultraviolet and infrared wavelengths, with very high brightness. The LED is based on the semiconductor diode. When a diode is forward biased, electrons are able to recombine with holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. An LED is usually small in area (less than 1 mm 2 ), and integrated optical components are used to shape its radiation pattern and assist in reflection. LEDs present many advantages over incandescent light sources including lower energy consumption, longer l

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

An inductor is a passive electronic component that stores energy in the form of a magnetic field. In its simplest form, an inductor consists of a wire loop or coil. The inductance is directly proportional to the number of turns in the coil. Inductance also depends on the radius of the coil and on the type of material around which the coil is wound.   The standard unit of inductance is the Henry abbreviated H. This is a large unit. More common units are the micro Henry, abbreviated µH (1 µH =10 -6 H) and the milli Henry, abbreviated mH (1 mH =10 -3 H). Occasionally, the nano Henry (nH) is used (1 nH = 10 -9 H).             inductors in series & parallel : applications : Inductors are used extensively in analog circuits and signal processing. Applications range from the use of large inductors in power supplies, which in conjunction with filter capacitors remove  fluctuations from the direct current output.          

INTRODUCTION : The capacitor is a component which has the ability or “capacity” to store energy in the form of an electrical charge producing a potential difference (Static Voltage) across its plates, much like a small rechargeable battery. CAPACITANCE : Capacitance is the electrical property of a capacitor and is the measure of a capacitors ability to store an electrical charge onto its two plates with the unit of capacitance being the FARD  (abbreviated to F ) named after the British physicist Michael Faraday. Capacitance is defined as being that a capacitor has the capacitance of One Farad when a charge of One Coulomb is stored on the plates by a voltage of One volt . Capacitance, C is always positive and has no negative units. However, the Farad is a very large unit of measurement to use on its own so sub-multiples of the Farad are generally used such as micro-farads, nano-farads and pico-farads, for example. Standard Units of Capacitance Micro farad  (μF)    1μF = 1/1,000,000