Explain construction, features and applications of Zener diode.

Construction of Zener Diode

A Zener diode is a special type of diode that exhibits a sharp breakdown voltage, known as the Zener voltage, at which it can conduct current in the reverse direction. This breakdown voltage is typically in the range of a few volts to a few hundred volts.

The construction of a Zener diode is similar to that of a regular diode, consisting of a p-n junction formed by the diffusion of impurities into a semiconductor material. However, the Zener diode has a heavily doped p-region and a lightly doped n-region. This results in a thin depletion region and a high electric field across the junction, which allows electrons to tunnel from the valence band of the p-region to the conduction band of the n-region, even at relatively low reverse voltages.

Features of Zener Diode

The following are the key features of a Zener diode:

• Sharp Breakdown Voltage: The Zener diode exhibits a sharp breakdown voltage, known as the Zener voltage (Vz), at which it can conduct current in the reverse direction. This breakdown voltage is typically in the range of a few volts to a few hundred volts.

• Voltage Regulation: Zener diodes are primarily used for voltage regulation purposes. When a Zener diode is connected in parallel with a load, it maintains a constant voltage across the load, regardless of variations in the input voltage or the load current.

• High Impedence: Zener diodes have a high impedance in the reverse direction, except at the breakdown voltage. This high impedance allows them to regulate voltage without significantly affecting the circuit current.

• Low Leakage Current: Zener diodes have a low leakage current in the reverse direction, except at the breakdown voltage. This low leakage current minimizes power dissipation and ensures efficient voltage regulation.

Applications of Zener Diode

Zener diodes have a wide range of applications in electronic circuits, including:

• Voltage Regulation: Zener diodes are commonly used for voltage regulation purposes. They are connected in parallel with a load to maintain a constant voltage across the load, regardless of variations in the input voltage or the load current.

• Voltage Reference: Zener diodes can be used as voltage references in various electronic circuits. They provide a stable and precise voltage reference, which can be used to calibrate other components or to set the operating point of electronic circuits.

• Clipping and Clamping Circuits: Zener diodes are used in clipping and clamping circuits to limit the voltage or current in a circuit. They can be used to protect sensitive components from overvoltage or to shape the waveform of a signal.

• Voltage Surge Protection: Zener diodes can be used for voltage surge protection by clamping the voltage across a sensitive component to a safe level. This prevents damage to the component caused by sudden voltage spikes or surges.

• Switching Circuits: Zener diodes can be used in switching circuits to control the flow of current. They can be used as voltage-controlled switches or as voltage-controlled rectifiers.

In summary, Zener diodes are special types of diodes that exhibit a sharp breakdown voltage, known as the Zener voltage. They are used in various electronic circuits for voltage regulation, voltage reference, clipping and clamping circuits, voltage surge protection, and switching circuits.