The zener diode is a particular type of diode that solves this problem. Apparatus a zener diode with small reverse breakdown voltage of about 6 volts, i. Zener diodes are heavily doped than ordinary diodes. A key difference is that a pn diode contains two depletion regions of opposite type. To study and draw the characteristics of rectifier filter circuit. Zener diodes are normal pn junction diodes operating in a reverse biased condition. Conclusion this experiment focuses on the investigation of.
Electrostatic analysis of a pn diode pnjuntion diode. Understanding zener diode datasheet specifications like any other component, the zener diode voltage reference diode has its characteristics specified. Question 4 explain how the characteristic curve of a 24 volt zener diode as plotted by a curve tracer di. The actual reverse voltage is repeatable for a given diode and is dependent upon the internal geometry and characteristics of the diode. We are going to learn about an experiment to find out the zener breakdown voltage and draw the characteristics of zener diode. A zener diode is a diode which allows current to flow in the forward direction in the same manner as an ideal diode, but will also permit it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage. Zener diode is a simplest type of voltage regulator. Write down all circuit equations and simplify as much as possible 2. The zener diode is a special type of diode that is designed to work in the reverse breakdown region.
To draw the characteristic curve of a zener diode and to. In zener diode, electric current flows from both anode to cathode and cathode to anode. It is also required to obtain the capacitancevoltage characteristics of the diode. Zener diode is a pn junction diode specially designed to operate in the reverse biased mode. To draw the characteristic curve of a zener diode and to determine its reverse breakdown voltage aim to draw the characteristic curve of a zener diode and to determine its reverse breakdown voltage. Brother fisher byuidaho compe 350 october 20, 2008. Only when the need for semi conductor materials exceeded, the urge to develop a device like zener diode spread deeper and wider. Carry out the recording for both forward and reversed bias characteristics.
The analysis is very similar to that of a metalsemiconductor junction. In reverse bias, a negligible constant current flow through the zener diode but the current becomes abruptly large at certain voltage. In simple words, it regulates maintain the voltage across its terminal when it is in reverse biased it is consisting of two terminals one is an anode and another is cathode kathode. Plot the forward biased diode graph taking vf readings along the xaxis and if readings. Diodes and diode circuits tlt8016 basic analog circuits 20052006 2 3. The early history of zener diode clarence melvin zener inventor of zener diode. Characteristics of a zener diode the above diagram shows the vi characteristics of. We have also learned about diffusion current, depletion region.
A zener diode is a heavily doped silicon crystal diode which allows current to flow in the forward direction in the same manner as an ideal diode. In the reverse biased mode zener diode has large breakdown voltage and though the current increases the voltage remains constant. Zener breakdown voltage should be approximately close to the desired voltage we want. A zener diode is constructed for operation in the reverse breakdown re gion. Observation of characteristics of a zener diode debangshu mukherjee bs. Its characteristics are otherwise very similar to common diodes. A free powerpoint ppt presentation displayed as a flash slide show on id.
In forward bias, the characteristics of zener diode are same as standard pn junction diode. In the forward biased mode the zener diode operates as a pn diode. In the case of normal diodes the diode damages at the break down voltage. Zener diode, resistors, power supply, multi meter circuit diagram. The contact surface between the layers of ptype and ntype semiconductor pieces plated together so as. Conclusion this experiment focuses on the investigation of the basic characteristics of a diode. Zener diodes are used in circuits to maintain a fixed voltage across a load. When the voltage across the terminals is reversed and the potential reaches the zener voltage or knee, the junction will break down and current will flow in the reverse direction a desired characteristic. It also permits the current to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage. It is acting as normal diode while forward biasing. Basic electronics notes on vi characteristics of zener.
For correct voltage regulation, we need to find out precisely what voltage should be across the zener diode. Working of the zener diode is similar to a pn junction diode in forward biased condition, but the uniqueness lies in the fact that it can also conduct when it is connected in reverse bias above its threshold breakdown voltage. Zener diode applications chapter 3 overview zener diodes zener characteristics zener diodes diode types rectifier zener lower vz due to more heavily. The symbol of zener diode is similar to the normal pn junction diode, but with bend edges on the vertical bar. April 7, 20 introduction a zener diode is a pn junction that has been specially made to have a reverse voltage breakdown at a specific voltage. From the experiment, the following conclusions were drawn. To draw the characteristic curve of a zener diode and to determine its reverse breakdown. The value of the resistance is the inverse of the slope of the iv characteristics of the zener diode d all of the mentioned. A semiconductor diode is prepared by joining p and n sections of a semi conducting. By adjusting the rheostat, voltmeter reading is increased from 0 and in each time note the.
Conventional diodes and rectifiers never operate in the breakdown region, but the zener diode can safely be operated at this point. Calculation do a curve fitting using the diode equation. Properties of junctions zener diode characteristics. To study and measure the effects of forward and reverse bias on the zener diode current. Zener diode characteristics, working and applications. Breakdown voltage is also known as zener knee voltage. The zener diode working principles and its various.
Zener diode lab viva questions and answers pdf free download. P517617 lec 5, p7 transistors transistors are the heart of modern electronics replaced vacuum tubes voltage and current amplifier circuits high frequency switching computers impedance matching low power small size, can pack thousands of transistors in mm2 in this class we will only consider bipolar transistors. A zener diode is a type of diode that allows current to flow in the conventional manner from its anode to its cathode i. Pdf explain a little about the zener diode sina taherinasab. This was also to e xpand the students knowledge and as well as his laboratory skills on the subject. Zener voltage reference diodes are able to run in reverse breakdown condition within their specifications very reliably. We operate a zener diode in reverse biased conditions, and this diode does not get damaged even when the voltage across this exceeds the reverse breakdown voltage. To plot the vi characteristics of zener diode under forward and reverse bias conditions. The vi characteristics of zener diode has been studied and graph is plotted.
To study the forward and reverse bias characteristics of diode and zener diode. The codes that represent zener diodes always begin with either of the letters bzx or bzy. Difference between stand and zener diode operation. The vi characteristic of zener diode indicates that characteristic of zener diode in forward bias is same as pn junction diode. Connections are made as shown in the circuit diagram. This was conducted as an introductory to electronics laboratory and in line with some topics in lecture classes. The reverse breakdown of a pn junction may occur either due to zener effect or avalanche effect. Diode, resistor, variable dc power supply, milliammeter, voltmeter, rheostat and wire. A diode, in electronics, is a two terminal electronic component with an asymmetric transfer characteristics, with low resistance to current flow in one direction and high resistance to current flow in the other direction. Zener diodes as voltage regulators a circuit diagram symbol for a zener diode. To construct a zener voltage regulator and experimentally determine the range over which the zener maintains a constant output voltage. Zener diode is a reversebiased heavilydoped pn junction diode which operates in the breakdown region.
Recipe for solving diode circuits state of diode is unknown before solving the circuit 1. Use the diode equation for that state to solve the circuit equations and find i d and v d 3. Zener diodes if we connect a diode and resistor in series with a dc voltage source so that the diode is forwardbiased, the voltage drop across the diode will remain fairly constant over a wide range of power supply voltages as in figure below a. This was a bad thing before the whole avalanche breakdown, large current.
Pn junction diode and its characteristics in chapter 1 understanding the pn junction, we have seen how a pn junction is formed from a ptype and ntype semiconductor. A zener diode is a diode that breaks down at a specific voltage when it is reverse biased. Zener diode experiment viva questions with answers characteristics mcqs interview questions. The voltage at which zener diode conducts in reverse bias is called as zener voltage vz. Full practical zener diode with readings download pdf. Zener diode is same as the normal pn diode but specially designed to operate in reverse bias. It has a particular voltage known as break down voltage, at which the diode break downs while reverse biased. Ppt zener diode applications powerpoint presentation. The graph has been plotted between voltage and current. Full practical zener diode with readings download pdf see. In this tutorial, we will examine the use of zener diode in pspice and learn about editing the properties of devices this tutorial is written with the assumption that you know how to do all of the basic things in. Use suitable input scales and calibrate the scale on the recording sheet.
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