I-v charateristics of zener diode

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1. Name : Shubhajit Chatterjee. Student Code : BWU/BEC/19/028. Course Name : Electronic Devices. Course code :PCC-EC301 . Program : Bachelor of Technology in Electronics & Communication Engineering. Semester : 3 rd Semester. TOPIC :I-V Characteristics of Zener Diode

2. A diode is a specialized electronic component with two electrode called anode and the cathode. Most diodes are made with semiconductor materials such as silicon , germanium or selenium. The symbol of a diode is shown below. The arrowhead points in the direction of conventional current flow in the forward biased condition. That means the anode is connected to the p side and the cathode is connected to the n side. DIODE ELECTRONICS & COMMUNICATION ENGINEERING DEPARTMRNT 1

3. Zener diode A Zener diode is a type of diode that permits current not only 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”. ELECTRONICS & COMMUNICATION ENGINEERING DEPARTMRNT 2

4. The arrowhead on a Zener diode symbol points in the direction of forward current when the diode is forward biased. The Zener diode is normally operated in reverse breakdown and the current direction is then from anode to cathode ELECTRONICS & COMMUNICATION ENGINEERING DEPARTMRNT 3

5. The most basic Zener diode circuit consist of a single Zener diode and a resist o r . The Zener diode provides the reference voltage, but a series resistor must be in place to limit the current into the diode otherwise a large amount of current would flow through it and it could be destroyed . The value of resistor calculated to give required value of current for supply voltage used. Zener Diode - Circuit ELECTRONICS & COMMUNICATION ENGINEERING DEPARTMRNT 4 Current=  

6. When a Zener diode is forward biased, it operates as a normal diode. In forward biased P side connected to + ve and N side connected to –ve terminal of battery. In this case the electrons and holes are swept across the junction an large current flow through it. Zener Diode – Forward bias The figure shows, the forward characteristics is same as that of ordinary forward biased junction diode . ELECTRONICS & COMMUNICATION ENGINEERING DEPARTMRNT 5

7. Zener Diode – Reverse biased In case of reverse biased current practically zero and at certain voltage which called Zener voltage the current increases sharply. Each Zener diode has breakdown rating which specifies the max voltage that can be dropped across it. In reverse direction however there is a very small leakage current between 0V and the Zener voltage –i.e. tiny amount of current is able to flow. Then, when the voltage reaches the breakdown voltage ( suddenly current flow through it.   ELECTRONICS & COMMUNICATION ENGINEERING DEPARTMRNT 6

8. Zener Diodes are used in the "REVERSE" bias mode, i.e. the anode connects to the negative supply, and from its I-V characteristics curve above, we can see that the Zener diode has a region in its reverse bias characteristics of almost a constant voltage regardless of the current flowing through the diode. This voltage across the diode (it's Zener Voltage, ) remains nearly constant even with large changes in current through the diode caused by variations in the supply voltage or load. This ability to control itself can be used to great effect to regulate or stabilise a voltage source against supply or load variations. The diode will continue to regulate until the diode current falls below the minimum value in the reverse breakdown region.   I-V characteristics of zener diode ELECTRONICS & COMMUNICATION ENGINEERING DEPARTMRNT 7

9. ELECTRONICS & COMMUNICATION ENGINEERING DEPARTMRNT 8 The most common application of Zener Diode Zener diodes are used in Voltage stabilizers (or) shunt regulators. used  in Over voltage protection circuits. Zener diodes are used in clipping and clamping circuits especially peak clippers . They are used as Reference elements. Used in switching applications.

10. ELECTRONICS & COMMUNICATION ENGINEERING DEPARTMRNT THANK YOU