P517617 lec5, p1 diodes and transistors diodes what do we use diodes for. Diode characteristics diode and diode circuits diodes. Diode characteristics diodes are the basic types of power semiconductor switching devices. Introduction to diodes university of california, san diego. The transistor characteristics are useful in amplifier design as well as understanding how transistors operate. If you need to use your diode on another day, mark it with a piece of tape with your name and leave it in the storage cubbies in the back of the lab. 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.
Page electro principles i etec 1120 114 the practical diode the practical diode considers many of the diode characteristics that must be dealt with on a regular basis. A diode is simply a pn junction, but its applications are extensive in electronic circuits. However, their iv characteristics are very different. The curve of the zener questions for the lab report. To study and measure the effects of forward and reverse bias on the zener diode current. One more property of the diode looking at figures 4 and 5, if you think about the diode symbol as an arrow you can infer that current can flow through the diode only in the direction of the arrow. The forward characteristics of a diode is non linear. It arises from the fact that the forward characteristics of real p n.
However, unlike a resistor, a diode does not behave linearly with respect to the applied voltage as the diode has an exponential currentvoltage iv relationship and therefore we can not described its operation by simply using an equation. Jul 27, 2018 1 compare the the purpose of this lab is to study the characteristics of the diode. To study and verify the functionality of a pn junction diode in forward bias b pointcontact diode in reverse lab report 1. Basic electronics notes on vi characteristics of zener diode. If the transistor is a pnp, then the arrow points to the base of the transistor, otherwise it points to the output. Measuring operating characteristics for a diode laser, including threshold current, output power versus current, and slope efficiency. It is a two terminal device with one terminal marked as positive and the other one as negative. Practical report on diode characteristics pdf scoop. An equation that models the iv characteristic of a nonideal diode is shown below. The ideal diode characteristic equation is known as the shockley equation, or simply the diode equation.
Diode characteristics 2012 summary this experiment was set up to investigate the different properties and characteristics of several different types of diode. You will be using a 2n2222 transistor so your data will be different. It means that a zener diode can be used as an alternate current path. Useful mathematical relations are shown and illustrated with plots. In this article we are going to discuss some of the basic characteristics of diodes and their properties. Deduce the forward working voltage of the diode vd. The purpose of this lab is to study the characteristics of the diode. Since the reverse saturation current, is is typically very small 109 to 1015 a, the expression. Diodes zetex neuhaus gmbh dzng promotes knowledge of the environment and the environmental awareness of its employees through continuous education and further training, and motivates them to act responsibly. Full practical zener diode with readings download pdf. When the positive polarity is at the anode the diode is forward biased and is conducting. Ideal diode and real diode a diode is said to be an ideal diode when it is forward biased and acts like a perfect conductor, with zero voltage across it. Diodes which are designed with adequate power dissipation capabilities to operate.
In the reverse, when we reverse bias the diode the depletion. To study the characteristics of the forward and reverse biased junction diodes. The symbol of the transistor has an arrow on the emitter. Lab 1 diode characteristics purpose the purpose of. Diode lasers have been called wonderful little devices. In general, the cathode of a diode is marked by a solid line on the diode. Diode iv characteristics contents that should be delivered for every report. Reverse characteristics curve for a junction diode. A light emitting diode led is essentially a pn junction diode. In the forward biased mode the zener diode operates as a pn diode.
Plot the vi characteristics and calculate the resistance levels 5. In the reverse biased mode zener diode has large breakdown voltage and though the current increases the voltage remains constant. Experiment guide university of california, berkeley. Some of the characteristics that will be investigated are the iv curve and the rectification properties.
Under a forward bias condition, this should be about. Now, we change the direction of voltage that is being applied. The threshold voltage is just a characteristic of each individual diode i. A pn junction diode is formed when a single crystal of semiconductor is doped with acceptors impurities pentavalent on one side and donor impurities trivalent on the other side. Use the diode equation for that state to solve the circuit equations and find i d and v d 3. The graph shows the reverse vi characteristics of the given pn junction diode. Plot a graph with reverse voltage along x axis and reverse current along y axis. Luyando flusa 2, benny alvarado rosa 2 universidad del turabo, puerto rico department of computer and electrical engineering 1 ieee, member, 2 elen 332 student abstract this laboratory report discusses the theoretical and practical dc and ac characteristics and the behavior of. Observation of the vi characteristic of a diode debangshu mukherjee bs. Three important characteristics of a diode are, first of all, the forward voltage drop.
Let us apply these two models and study the very practical diode circuit shown in figure 6. Some of the voltage and current division lab report. 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. Thus the load voltage remains at constant by altering the current flow through the zener diode. Because diodes of the same type can have significantly different characteristics, use the same diode for all experiments in this lab. Simulator procedure as performed through the online labs select the characteristics of diode from the drop down list. Pn junction is formed by bringing a p type material in contact with n type material. The lead connected to the ptype material is called the anode and the lead connected to the ntype material is the cathode. The diode is a device formed from a junction of ntype and ptype semiconductor material.
The precautions are quite similar to that taken in a normal diode i. The vi characteristics of the ideal diode are shown in the figure below. To study and verify the functionality of a pn junction diode in forward bias b pointcontact diode in reverse. A zener diode is a type of diode that permits current to flow in the forward direction like a normal diode, but also in the reverse direction if the voltage is larger than the breakdown voltage known as zener knee voltage or zener voltage.
Diode iv characteristics the iv graph for a nonideal diode is shown in figure 2, along with an ideal approximation to accommodate the nonzero threshold voltage. Forward bias reverse bias v d volts i d ma v d volts i d a b reverse bias condition. Pdf this paper describes an experiment that studies the effect of diode temperature and. Similarly, when the diode is reversed biased, it acts as a perfect insulator with zero current through it. Electro principles i page the pn junction diode etec 1120. Ideal characteristics forward characteristic reverse characteristic calculations from graph. The purpose of this laboratory investigation is to determine the voltage and current characteristics of several pn junction diodes including the. 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. A pn junction diode is one of the simplest semiconductor devices around, and which has the characteristic of passing current in only one direction only. This was a bad thing before the whole avalanche breakdown, large current. The data below were collected for the example of a npn 2n36443 transistor using the circuit below. Basics currentvoltage characteristic of a zener diode with a breakdown voltage of 17 volt. You can always remember that the arrow points at the n material. Reverse biased pn junction diode when a diode is connected in a reverse bias condition, a positive voltage is applied to the ntype material and a negative voltage is applied to the ptype material.
Zener diodes when we first talked about practical diodes, it was mentioned that a parameter associated with the diode in the reverse bias region was the breakdown voltage, v br, also known as the peakinverse voltage piv. To construct a zener voltage regulator and experimentally determine the range over which the zener maintains a constant output voltage. Diodes and diode circuits tlt8016 basic analog circuits 20052006 2 3. Write down all circuit equations and simplify as much as possible 2. To study and verify the functionality of a pn junction diode in forward bias b pointcontact diode in reverse bias components equipments required. Diode is an electronic device having conductor at their ends. To study the forward and reverse bias characteristics of diode and zener diode.
Draw the i v characteristics curve of diode from the reading obtain in this experiment. Copy all of the specifications for each diode as well as of the specification definitions for your final lab report. Most of the commercial leds are realized using a highly doped n and a p junction. Recipe for solving diode circuits state of diode is unknown before solving the circuit 1. The constant vz developed across the diode can then be applied to a load. The vi characteristics of a zener diode can be divided into two parts i forward characteristics. The principle behind the diode is similar to a valve or a gate, which lets electricity flow only in one direction simple. Observation of characteristics of a zener diode debangshu mukherjee bs. However, unlike a resistor, a diode does not behave linearly with respect to the applied voltage as the diode has an exponential currentvoltage iv relationship and therefore we can not. The diode will be easier to understand if we compare the diode to another two terminal device we know and love the resistor. Compare the theoretical and practical values cutin voltage and resistances.
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