*Question E6C01:
What is the function of hysteresis in a comparator?*  

*Correct Answer is  A: To prevent input noise from causing unstable output signals*  

### AI Response: (may contain errors)  

Hysteresis in a comparator is a technique used to improve the stability of the output signal by creating a threshold range for switching. 

### Correct Answer Explanation:
- **A: To prevent input noise from causing unstable output signals**  
  This is the correct answer. Hysteresis introduces two different threshold voltage levels for switching the output state. When the input voltage crosses the upper threshold, the output switches high, and it remains high until the input drops below the lower threshold. This prevents small fluctuations or noise in the input signal from causing the output to toggle rapidly, leading to a stable output.

### Incorrect Answer Explanations:
- **B: To allow the comparator to be used with AC input signals**  
  This is incorrect. Hysteresis does not specifically enable the use of AC signals. Comparators can handle AC signals, but hysteresis is primarily used to stabilize the output against noise, not to accommodate AC inputs.

- **C: To cause the output to continually change states**  
  This is incorrect. Hysteresis is designed to prevent continual state changes by providing a stable switching threshold. Without hysteresis, a noisy input could cause the output to toggle rapidly, but hysteresis mitigates this.

- **D: To increase the sensitivity**  
  This is incorrect. Hysteresis does not increase sensitivity; rather, it stabilizes the output by creating a defined range for switching. Increased sensitivity would mean the comparator responds to smaller changes in input, which is not the purpose of hysteresis.

### Summary:
- Hysteresis is crucial for ensuring stable output in the presence of noise.
- It creates distinct upper and lower thresholds for switching, preventing rapid toggling.
- Understanding hysteresis helps in designing reliable comparator circuits.