ZENER DIODE

AIM:

Simulate the electrical characteristics of a Zener diode, analyze its performance under both forward and reverse bias conditions, and determine key Zener diode parameters.

Objective:

• Explain the concept of reverse breakdown voltage in a Zener diode.

• Compare simulated data with theoretical models and manufacturer datasheet values.

Principle:

A Zener diode is a specialized semiconductor diode designed to operate in the reverse breakdown region. Unlike standard diodes, which are typically damaged under high reverse voltage, Zener diodes are specifically constructed to utilize this property without damage.

Working:

Forward Bias Operation:

• When the anode is connected to the positive terminal and the cathode to the negative terminal of the power supply, the Zener diode becomes forward-biased.

• In this state, the diode allows current to flow easily from anode to cathode once the forward voltage threshold is exceeded (approximately 0.7V for silicon-based Zener diodes).

Reverse Bias Operation:

• When the cathode is connected to the positive terminal and the anode to the negative terminal of the power supply, the Zener diode is reverse-biased.

• Under normal reverse-bias conditions (below the breakdown voltage), the diode restricts current flow, allowing only a minimal leakage current.

• When the reverse voltage exceeds the breakdown voltage, the Zener diode enters the reverse breakdown region, conducting current while maintaining a stable voltage across its terminals.

Connections:

Forward Bias Configuration:

1. Connect the anode of the Zener diode to the positive terminal of the power supply.

2. Connect the cathode to one end of a resistor.

3. Attach the other end of the resistor to the negative terminal of the power supply.

Reverse Bias Configuration:

1. Connect the cathode of the Zener diode to the positive terminal of the power supply.

2. Connect the anode to the ground (negative terminal).

3. Place a resistor in series between the power supply and the cathode of the Zener diode.

4. If a load is used, connect it in parallel with the Zener diode.

CIRCUIT DIAGRAM:

Forward Bias

                                                   Reverse Bias