We try to see the voltagecurrent realtion in diodes by applying a voltage across it and measuring the corressponding current. Diodes overview diodes are mostly used in practice for emitting light as light emitting diodes, leds or controlling voltages in various circuits. 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. Zener effect dominates at reverse voltages less than 5 volt whereas avalanche effect dominates above 5 v. Plot a graph with reverse voltage along x axis and reverse current along y axis. Zener diode experiment viva questions with answers characteristics mcqs interview questions. To study and measure the effects of forward and reverse bias on the zener diode current. The vi characteristic of scr, mosfet, led, pn junction diode, and zener diode is explained here. Placing the zener diode in parallel with the load as shown in figure 3. They provide a lowcost and no frill method for voltage regulation. When you take your measurements for this experiment, you will find the response of your.
Diodes which are designed with adequate power dissipation capabilities to operate in the break down region are called as break down or zener diodes. Use the diode equation for that state to solve the circuit equations and find i d and v d 3. How do you construct the laboratory experiment that will allow you to make this determination. The experiments in this laboratory exercise will provide an introduction to. The maximum forward current is limited by heatdissipation ability of the diode.
To construct a zener voltage regulator and experimentally determine the range over which the zener maintains a constant output voltage. To study of characteristics of zener diode as constant voltage. This paper shows the vi characteristics of diode through pc that records the. Calculation do a curve fitting using the diode equation. It is also required to obtain the capacitancevoltage characteristics of the diode.
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. Diode is an electronic device having conductor at their ends. Replace the procedure in experiment 3 with the following procedure 1 measure the voltage and current through a signal diode use a 1n4148 from your graymark kit these are also available in the instrument room. Electrostatic analysis of a pn diode pnjuntion diode.
Zener diodes are a special kind of diode which permits current to flow in the forward direction. Write down all circuit equations and simplify as much as possible 2. Simulator procedure as performed through the online labs select the characteristics of diode from the drop down list. Zener diodes with 12 v operation are particularly prone to becoming wideband noise generators if a feed resistor limits the current and the diode skips between zener action and avalanche. Vi characteristics are used for explaining the relationship between voltage and current characteristics of any given electrical component.
Pdf v i characteristics of diode through computer researchgate. The polarity of the voltage source is such that the photodiode is reversed biased. Hence the forward characteristic is the same for both pn junction diode and zener diode. With your lab partner, brainstorm on the following ideas. Under a forward bias condition, this should be about.
A zener diode is constructed for operation in the reverse breakdown re gion. This was conducted as an introductory to electronics laboratory and in line with some topics in lecture classes. A voltage stabilizer is a combination of elements that are designed to ensure the output voltage of a supply fairly remains constant. It has a particular voltage known as break down voltage, at which the diode break downs while reverse biased. The principle behind the diode is similar to a valve or a gate, which lets electricity flow only in one direction simple english wikipedia, diode. Each diode was investigated by plotting the iv curve using a precision sourcemeasurement unit b2902a and a laptop with the corresponding quick iv measurement software installed. The negative part of the voltage axis corresponds to when the diode is reverse biased and the positive part is when the diode is forward biased. To study the forward and reverse bias characteristics of diode and zener diode. Breakdown voltage is also known as zener knee voltage.
In forward bias condition, current is constant until certain voltage is reached. As shown in the figure above, the resistor is selected so that when the input voltage v in is minimum and the load current i l is maximum than the current through the zener diode is, at least, minimum i z. Feb 15, 2016 class 12th physics experiment to determine iv characteristics of a pn junction diode in forward bias donate with paytm. The diode is firmed by doping a semiconductor like silicon or germanium with. It consists of a pn junction with highly doped regions.
The critical parameter of this type of diodes is the zener breakdown voltage. A zener diode is a special kind of 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 knee voltage or zener voltage. It maintains a constant voltage across the device, so it is typically employed as a simple voltage regulator in many circuits. Zener diodes are normal pn junction diodes operating in a reverse biased condition. To analyze the input and output characteristics and to. These conditions destroy normal diodes, but a zener conducts a small amount of current. In this experiment, we try to observe the relation between the voltage and corressponding current generated. For instance, to invoke a 1n4148 diode from the builtin library, we use a command of the type dxxx a c d1n4148. We have also learned about diffusion current, depletion region. Measure voltage across diode and current through diode.
Under forward bias, it needs a small voltage to conduct. The analysis is very similar to that of a metalsemiconductor junction. A zener diode is a type of diode that allows current to flow in the conventional manner from its anode to its cathode i. In experiment b, a 6v zener diode used is conducting. Zener diode as voltage regulator and its vi characteristics. Pn junction diode experiment forward characteristics by. The vi characteristics of a diode can be forward or reverse. Part bfrom both experiment we can conclude the diode can become insulator when inreverse biased and also can be a conductor when in forward biased because thatstime the resistance become low and can make the current easily flow trough diode. The vi characteristic of zener diode indicates that characteristic of zener diode in forward bias is same as pn junction diode.
Diode characteristics diode and diode circuits diodes and. You diodes will use the bit bucket breadboarding system to build and test several dc and ac diode circuits. The operating characteristics of a diode can be illustrated with a graph of the current through the diode plotted against the applied voltage. About the channel in this channel, you will find easiest explaination of graduation physics topics.
To draw the characteristic curve of a zener diode and to determine its reverse break down voltage. The early history of zener diode clarence melvin zener inventor of zener diode. The reverse breakdown of a pn junction may occur either due to zener effect or avalanche effect. Zener doide is a special diode with increased amounts of doping. Zener diode lab viva questions and answers pdf free download.
The first thing we want to do is look at diode characteristics. In the case of normal diodes the diode damages at the break down voltage. Zener diode is a special kind of diode which permits the flow of current in the forward direction as well as in reverse direction when the voltage is above a certain voltage known as breakdown or zener voltage. But simulation doesnt necessarily give the true effect of any experiment as the.
Diode characteristics 2012 summary this experiment was set up to investigate the different properties and characteristics of several different types of diode. Silicon diode characteristics part 1 university of texas. Diodes incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to any product herein. A diode is simply a pn junction, but its applications are extensive in electronic circuits. Zener diode, resistors, power supply, multi meter circuit diagram. Definition ptype semiconductor is suitably joined to ntype semiconductor,to conduct surface is called pn junction. Let vcc be the dc voltage source to be used in the experiment. Basic electronics notes on vi characteristics of zener. To obtain vi characteristics of zener diode with graph electronics practical zener diodes are a special type of semiconductor diode devices that allow current to flow in one direction only that also allow current to flow in the opposite direction, but only when exposed to enough voltage. The zener diode mainly operates in reverse biased condition. The details of the device connection are available online. Keep the multisim file handy to refer it to in the lab. Initially, a negligible constant current flow through the zener diode in its reverse bias but at certain voltage, the current becomes abruptly large.
Three important characteristics of a diode are, first of all, the forward voltage drop. The forward characteristics of a diode is non linear. Sep 12, 2015 zener diode iv characteristics curve in the forward bias condition, the zener diode behaves like an ideal diode within specified current and power limits, but it differs in reverse bias condition where the zener diode has very steep avalanche characteristic at the breakdown voltage in reverse bias condition. To study and draw the characteristics of rectifier filter circuit. In reverse bias, a negligible constant current flow through the zener diode but the current becomes abruptly large at certain voltage. When we apply a voltage more than the zener breakdown voltage can range from 1. The symbol of zener diode is similar to the normal pn junction diode, but with bend edges on the vertical bar. Exploiting this characteristic of zener diodes allows for simple, inexpensive voltage regulators. Zener diode working, characteristics and application as voltage regulator. These include generic diode, schotty diode, shockley diode, constantcurrent diode, zener diode, light emitting diode, photodiode, tunnel diode, varactor, vacuum tube, laser diode, pin diode, peltier diode, gunn diode, and so on. Observation of characteristics of a zener diode debangshu mukherjee bs. Conclusion this experiment focuses on the investigation of.
Use suitable input scales and calibrate the scale on the recording sheet. Zener diodes are heavily doped than ordinary diodes. Experiment 6, photodiode and phototransistor current measurements. Dec 16, 2012 and the best rectifier is fullwave rectifier. It is the reverse biased havily doped silicon or germanium pn junction diode which is operated in the breakdown region where current is limited by both external resistance and power dissipation of the diode. However, the reason for this is some external circuit is required in order to protect the device from the excess current. When a zener diode operates in the breakdown region, it does not burn rapidly.
Theory the japanese physicist leo esaki invented the tunnel diode in 1958. Because of the thinness of the junction, the electrons can pass through the potential barrier of the dam layer at a suitable polarization, reaching the energy states on the. Secondly, a 24v hot plugin was tested to show that without the tvs zener diode, the voltage spike can exceed the bq243xx absolute maximum voltage of 30 v. Draw the reverse characteristics of zener diode and determine its break down voltage.
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. To draw the iv characteristic curves of a pn junction diode in forward bias and reverse bias. Zener diode is a pn junction diode specially designed to operate in the reverse biased mode. In case of junction diodes, there are two types of characteristics, forward and reverse characteristics. To get familiar with working knowledge of the following instruments. Since the zener diode s reverse bias characteristics are what is needed to regulate the voltage, it is connected in reversed bias mode, with the cathode being connected to the positive rail of the circuit. You are tasked to determine experimentally the characteristic curve of a reversebiased zener diode. To draw the characteristic curve of a zener diode and to. When the load current is the highest the zener conducts the least current while at lowest load current it conducts the most current. It also permits the current to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage.
In the reverse biased mode zener diode has large breakdown voltage and though the current increases the voltage remains constant. The graph showing the forward bias voltage and forward current is known as the forward characteristics, and that showing the reverse bias voltage and reverse current is known as the reverse characteristics. Recipe for solving diode circuits state of diode is unknown before solving the circuit 1. Voltagecurrent characteristics of a zener diode physics. Useful mathematical relations are shown and illustrated with plots. There are several drawbacks, however, that will be discussed shortly. Carry out the recording for both forward and reversed bias characteristics. The circuit diagram to plot the vi characteristics of a zener diode is shown. In zener diode, electric current flows from both anode to cathode and cathode to anode. The critical parameter of this type of diodes is the zener. As mentioned earlier, the characteristics of the zener diode make it ideal for application as a voltage regulator. Zener diode working, characteristics and application as.
This activity can be used to make a noise generating test circuit, but should be avoided in most applications. A diode is simply a pn junction see introduction into semiconductor physics with the following characteristics. You may use either of three methods to measure the vi characteristics. Only when the need for semi conductor materials exceeded, the urge to develop a device like zener diode spread deeper and wider. Silicon is preferred to diode because of its higher temperature and current capability. The zener diode working principles and its various. Reverse dc power supply polarity for reverse bias repeat the above procedure for the different values of supply voltage for reverse bias draw vi characteristics for forward bias and reverse bias in one graph. Building a voltage regulator with an ideal zener diode, construction of a voltage regulator is easy, simply connect the diode between the. A main difference between zener diodes and regular silicon diodes is.
Zener diode characteristics zener regulator prelab. Ammeter circuit diagram theory zener diode is a pn junction diode specially designed to operate in the reverse biased mode. The figure below shows the characteristic curve of a zener diode. Zener diodes are designed for specific reverse breakdown voltage called zener breakdown voltage vz. In the forward biased mode the zener diode operates as a pn diode. A key difference is that a pn diode contains two depletion regions of opposite type. 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. It means that the anode must be connected to the negative side of the voltage source and the cathode must be connected to the positive side. A graph showing the variation of voltage applied across the terminals of a diode to the corresponding current is called characteristics of a diode.
Iv characteristics pn junction diode theory a semiconductor pn junction diode is a two terminal electronic device that allows current in only one direction. If you continue browsing the site, you agree to the use of cookies on this website. Again, in this lab, there were two di erent kinds of power supplies built. Aim to plot the reverse characteristics of zener diode and to find the breakdown voltage components and equipments needed 1. We use zener diodes for voltage regulation and voltage stabilisation. Zener diode charecteristics electronic circuits and. The graph shows the reverse vi characteristics of the given pn junction diode. The forward bias characteristic of zener diode is same as the normal pn junction diode but in reverse bias it has different characteristic. Lab experiment related theory available in following books. The value of the resistance is the inverse of the slope of the iv characteristics of the zener diode d all of the mentioned. Zener diodes are normally used only in the reverse bias direction. One or more identical devices labelled pn diode are available in weblab under the devices menu. To verify the vi characteristics of pn junction diode and zener diode. Iv characteristics of zener diode make it suitable for application such as a voltage regulator.
You can check out and keep the portable breadboards, vb106 or vb108, from the 111lab for yourself only one each please this is the first of three labs on basic semiconductor components. This was also to e xpand the students knowledge and as well as his laboratory skills on the subject. Apparatus a zener diode with small reverse breakdown voltage of about 6 volts, i. The codes that represent zener diodes always begin with either of the letters bzx or bzy. It is acting as normal diode while forward biasing. You must also design a circuit that demonstrates the operation of a 7 v 5% loaded zener regulator powered by a 12 v dc voltage source.
Therefore, knee voltage and forward resistance can be determined as explained in the previous experiment. Diodes incorporated does not assume any liability arising out of the application or use of any product. Correspondingly, is there a way we could determine the type of breakdown action from experimental measurements on a zener diode. Conclusion this experiment focuses on the investigation of the basic characteristics of a diode. This is to compensate for the damage that occurs in the case of a pn junction diode when the reverse bias exceeds the breakdown voltage and thereby. Zener diode is a reversebiased heavilydoped pn junction diode which operates in the breakdown region. Jan, 2015 pn junction diode characteristics lab expriment 1. A zener diode is a diode designed to operate in the breakdown region. To obtain vi characteristics of zener diode with graph. Objective in this lab you are to measure iv characteristics of rectifier and zener diodes in both forward and reversebias mode, as well as learn to recognize what mechanisms cause current flow. To study the characteristics of commonemitter npn or pnp transistor and to find out the values of current and voltage gains. Unlike ordinary pn junction diode, the reverse current in zener diode is measured using milliammeter due to the large flow of current.
Zener diode is used for voltage regulation purpose. A semiconductor diode is prepared by joining p and n sections of a semi conducting. From the experiment, the following conclusions were drawn. 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. In this experiment also we know the how to differentiate. The diodes are classified into different types based on their working principles and characteristics.
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