From the iv characteristics curve above, we can see that the zener diode has a. When we apply a voltage more than the zener breakdown voltage can range from 1. Zener diode definition 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. In forward bias, the characteristics of zener diode are same as standard pn junction diode. The iv characteristics curve of a zener diode, shown below, is the curve which shows the current. Vi characteristics of pn junction diode in 3biasing modes. The figure below shows the characteristic curve of a zener diode. Voltampere vi characteristics of a pn junction or semiconductor diode is the curve between voltage across the junction and the current through the circuit.
It provides the constant voltage from the fluctuating voltage source to the load. The vi characteristics of pn junction diode in forwarding bias are nonlinear, that is, not a straight line. Normally it is called the vi characteristics of a general p n junction diode. Voltage regulation using zener diodes bryan witherspoon november 8, 2008 abstract in digital or mixedsignal applications, there is a need to precisely regulate the voltage entering or exiting a circuit. Zener voltage z 1 10 100 1,000 1 10 100 v, zener voltage v fig. The characteristics of a junction diode demonstrate that it is designed largely for operating in the forward direction. Electrons diffuse across the junction and combine with majority holes. Its characteristics are otherwise very similar to common diodes.
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. Electronics tutorial about the zener diode and how the zener diode can be used. Zener diodes are heavily doped than ordinary diodes. Zener diode is same as the normal pn diode but specially designed to operate in reverse bias. Applying a large amount of forward bias causes greater forward current with a small value of forward voltage. But due to higher doping concentration, higher current flows through the zener diode. The above diagram shows the vi characteristics of the zener diode behavior. A normal pn junction diode is usually fabricated by adjusting the ptype and ntype semiconductors on a single semiconductor crystal. Zener diode operation and applications ece tutorials.
The basic purpose of a power supply is to provide one or more fixed voltages to the working circuit, with sufficient current handling capacity to maintain the operating conditions of the circuit. The forward bias characteristic of zener diode is same as the normal pn junction diode but in reverse bias it has different characteristic. The vi characteristics of a zener diode is shown in the below figure. The zener regulator is composed of resistor r1 and zener diode cr1 the resistor characteristics are shown in table iv. Lets try again, this time with our friend, the zener diode. The zener diode is a diode designed to operate in the breakdown region and have a specific negative voltage called the zener voltage. The heart of the zener voltagereference is shown in the. Basic electronics notes on vi characteristics of zener diode in pdf. But zener breakdown voltage occurs when the reverse bias voltage is greater than a predetermined voltage. Zener diodes are used in circuits to maintain a fixed voltage across a load.
Clarence melvin zener inventor of zener diode only when the need for semi conductor materials exceeded, the urge to develop a device like zener diode spread deeper and wider. 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. The iv characteristic of the zener diode is not completely vertical in the breakdown region. The iv characteristic curve of the diode is shown on figure 1b. Analysis and measurement of a zener diode voltagereference. The type of diode also has some importance in defining the forward voltage drop.
Zener diode characteristics in the forward region the zener diode acts like a regular silicon diode, with a 0. Diode signal processing applications are also introduced including signal clipping and rectification. As mentioned earlier, the characteristics of the zener diode make it ideal for application as a voltage regulator. A diode allow electric current to pass in forward direction and block current in reverse direction. Basics currentvoltage characteristic of a zener diode with a breakdown voltage of 17 volt. Hbd854 zener theory and design considerations handbook. The voltage at which zener diode conducts in reverse bias is called as zener voltage vz. The forward characteristics of zener diode are similar to that of normal pn. Zener diode as voltage regulator tutorial electronicstutorials. Typically, a silicon diode will have a vf around 0. Because of this ability to reverse a portion of the current, zener diodes offer several advantages in a circuit that normal diodes dont.
Zener diode working with circuit diagram and applications. But for simplicity, both types are called zener diodes. This voltage regulator is a pn junction diode that has a precisely tailored impurity distribution to provide a welldefined breakdown voltage. When a forward voltage is applied, current flows through it.
Zener diode connection characteristics of a zener diode. Normally the voltage is taken along the xaxis and current along yaxis. However, when reverse biased voltage is applied to the zener diode, it works in different manner. 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. The forward biasing and reverse biasing of the zener. For zener diodes, silicon is preferred to ge because of its high temperature and current capability. This manual was prepared to acquaint the engineer, the equipment. The other differences between the pnjunction and zener diode are shown in the comparison. Vi characteristics of pn junction diode electronics post.
We will focus our analysis in the reverse bias region of the iv curve. Explain how normal diodes might be used as crude substitutes for a zener diode in the following circuit. The zener diode has a unique property that offers a simple, lowcost solution to. Practical report on diode characteristics pdf scoop. A zener diode is a type of diode that allows current to flow in the conventional manner from its anode to its cathode i. When forward biased voltage is applied to the zener diode, it works like a normal diode.
The slope of the pn junction diode in forwarding bias shows the resistance is very low. It can be designed to have a breakdown voltage over a wide range from 0. A zener diode is a special diode that is optimized for operation in the breakdown region. Zener pdf datasheets, circuit,characteristics,diagram,price of zener. Vi characteristics of zener diode vi characteristics of. This paper shows the vi characteristics of diode through pc that records the different readings of voltage across diode and current.
Some of the voltage and current division lab report. The forward characteristic of the zener diode is similar to a normal diode which is clearly seen in the figure above. The vi characteristics or voltagecurrent characteristics of the pn junction diode is shown in the below figure. Zener diode is a simplest type of voltage regulator. 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. A zener diode is a diode that breaks down at a specific voltage when it is reverse biased. A specific diodes vf depends on what semiconductor material its made out of. Zener diode characteristics, working and applications. In this experiment, we try to observe the relation between the voltage and corressponding current generated. The voltage change for a given change in current is the resistance of the diode. Diode characteristics 2012 summary this experiment was set up to investigate the different properties and characteristics of several different types of diode. Zener diodes are simple and useful devices for building voltage regulator circuits, but are times when you may have to improvise in the absence of the proper zener diode.
This article will help to explain the characteristics which make up zener diodes, specifically how the voltage across a zener diode varies with the current flowing through it. This video lecture explains the vi characteristics of the zener diode. Many early inventions were made till 1905, yet a more focused work on semiconductor devices were started only at the time of the second world war. Finally, lets try using one fat 20 v zener diode type 1n5357brlg, to drop some of the load.
Characteristics of a zener diode the above diagram shows the vi characteristics of. Initially, a negligible constant current flow through the zener diode in its reverse bias but at certain voltage, the current becomes abruptly large. As voltage stabilizer the zener diode is used for regulating the voltage. When the diode is connected in forward bias diode acts as a normal diode. Pdf explain a little about the zener diode sina taherinasab. Zener diodes the simplest of all voltage regulators is the zener diode voltage regulator. This nonlinear characteristic illustrates that during the operation of the n junction, the resistance is not constant. The symbol of zener diode is shown in the figure below. The vi characteristics of a zener diode is as shown in the figure below. Measure and plot the vi terminal characteristics of pn junction diodes.
Placing the zener diode in parallel with the load as shown in figure 3. Z ener diode as the name suggests is a two terminal device with two terminals being anode p and cathode n. The figure represents the curve for both silicon and germanium diodes. The horizontal line in the below figure represents the amount of voltage applied across the pn junction diode whereas the vertical line represents the amount of current flows in the pn junction diode. The zener diode is connected in parallel across the load and maintain the constant voltage v z and hence stabilises the voltage. Here you will learn, how the zener diode is used in reverse biasing. Forward biasing will cause a large i f with a rather small value of v f. This means that for slight changes in current, there will be a small change in the voltage across the diode.
Then, the output on the anode of the zener is just 16 v, well within the safe input range of the regulator. The breakdown voltage of a zener diode can be set by controlling the doping level. Zener diode characteristics in the forward region, the zener diode acts like a regular silicon diode, with a 0. This post includes explanation of operation of zener diode and vi characteristics of zener diode. In forward bias zener works as an ordinary diode but when it is operated in reverse bias its shows the specialty of voltage regulation, it must be noted that in fig given below.
Pdf the various attempts have been made to simulate the experiments using computer. Reverse biasing will generally not cause current conduction until higher values of reverse voltage are reached. When the reverse bias voltage is greater than a predetermined voltage then the zener breakdown voltage occurs. Every zener diode has particular zener voltage knee voltages in that they can regulate voltage. Pdf v i characteristics of diode through computer researchgate. The following are the main application of the zener diode. Electrical characteristics tamb 25 c, unless otherwise specified part number zener voltage range 1 test current reverse leakage dynamic resistance f 1 khz surge current 3 regulator 2. 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.
Limitations of switching frequency are also investigated. Zener diodes as voltage regulators a circuit diagram symbol for a zener 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. Unlike normal diodes, which allow only forward current, zener diodes will allow a current to move in reverse when voltage exceeds a specified value, preventing breakdown of the diode. This was a bad thing before the whole avalanche breakdown, large current. Vz is the reverse breakdown voltage and vg is the forward voltage drop across the diode. Zener diode as voltage regulator and its vi characteristics. In breakdown the voltage across the zener diode is close to. Semiconductor is basically a pn junction where the ptype silicon contacts with the ntype.
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