Question
What is the function of hysteresis in a comparator?
Answer Options
- A) To prevent input noise from causing unstable output signals
- B) To allow the comparator to be used with AC input signals
- C) To cause the output to continually change states
- D) To increase the sensitivity
Correct Answer: A
Explanation
A comparator is a digital circuit that compares two input voltages and changes its output state (high or low) when the input signal crosses a reference threshold. If the input signal is noisy or contains ripple, it may hover near the threshold voltage, causing the output to rapidly switch back and forth (chatter or oscillation).
Hysteresis is a function added to a comparator, usually through positive feedback, to create two separate switching thresholds: a higher one for switching high, and a lower one for switching low. The primary function of this dual threshold is to prevent input noise from causing unstable output signals. Once the input crosses the threshold, the output stays stable until the input crosses the other threshold, well away from the initial switching point.
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