Question

Diagram shows a circuit consisting of some elements. The input and output of the circuit is shown. Choose the correct option that shows the component in box. (Zener diode has a breakdown potential of 5V)





Options are:



 

• A. (1)
• B. (2)
• C. (3)
• D. (4)

Answer 1

The Correct Option is D

The circuit provided includes two Zener diodes with a breakdown voltage of 5V. The goal is to identify the correct component that should be placed within the box to transform the sinusoidal input voltage into the desired output voltage as shown in the graphs.

Analysis of the Input and Output Signals

Input: The input voltage is given as a sinusoidal wave with peaks at ±20V.

Output: The output voltage waveform is clipped at ±5V, indicating that the Zener diodes are used to clamp the voltage at these levels.

Role of Zener Diodes

Zener diodes are used for voltage regulation and clamping. In reverse bias, they maintain a constant voltage equal to the breakdown voltage, thus preventing any voltages higher than this value from appearing across them.

Identification of the Correct Option

Examining the given options:

1. Option 1: Uses a single Zener diode and resistor combination which is not suitable as both positive and negative clamping is required.
2. Option 2: Similar to option 1 but arranged differently, still unsuitable due to no clamping at both peaks.
3. Option 3: Two diode series combination which doesn't match the needed configuration for clamping both peaks.
4. Option 4: Contains two Zener diodes in opposite parallel directions, which can clamp both positive and negative voltages at their breakdown levels (±5V).

Based on the configuration and the characteristics of Zener diodes needed to achieve the desired output waveform, Option 4 is correct. This option ensures both positive and negative cycles of the waveform are limited to ±5V.