Updated: Dec 9, 2025 | Source: 2024-2028 Question Pool | Topic: E6C
E6C01E6C

What is the function of hysteresis in a comparator?

Deep Dive: E6C01

The correct answer is A: To prevent input noise from causing unstable output signals. What is the function of hysteresis in a comparator is to prevent input noise from causing unstable output signals. Hysteresis prevents oscillation from noise. For amateur radio operators, this is important for digital circuits. Understanding this helps when using comparators.

Why Other Answers Are Wrong

Option B: Incorrect. Allow comparator to be used with AC input signals isn't the function - hysteresis prevents noise from causing instability. AC input isn't the function. Option C: Incorrect. Cause output to continually change states isn't the function - hysteresis prevents instability, not causes it. Continual change isn't the function. Option D: Incorrect. Increase sensitivity isn't the function - hysteresis actually reduces sensitivity to prevent noise. Increase sensitivity isn't the function.

Exam Tip

Hysteresis in comparator = prevent input noise from causing unstable output. Think 'H'ysteresis = 'H'elps 'S'tability (prevents noise). Hysteresis prevents oscillation from noise. Not AC input, not continual change, not increase sensitivity - just prevent noise instability.

Memory Aid

Hysteresis in comparator = prevent input noise from causing unstable output. Think 'H'ysteresis = 'N'oise 'P'revention. Hysteresis prevents oscillation from noise. Important for digital circuits.

Real-World Example

Hysteresis in a comparator: Its function is to prevent input noise from causing unstable output signals. Without hysteresis, noise near the threshold can cause the output to oscillate. Hysteresis creates a dead band that prevents this. This is the function - prevent noise instability.

Source & Coverage

Question Pool: 2024-2028 Question Pool

Subelement: E6C

Reference: 2024-2028 Question Pool · E6 - Circuit Components

Key Concepts

Hysteresis Comparator Prevent input noise Unstable output signals

Verified Content

Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E6C topic.