Schmitt trigger hysteresis calculation: Given VT+ = 2.0 V and VT− = 1.2 V, compute the hysteresis voltage (width) of the Schmitt trigger.
Digital Electronics
Digital Design
Difficulty: Easy
Choose an option
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A0.4 volt
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B0.6 volt
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C0.8 volt
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D1.2 volts
Answer
Correct Answer: 0.8 volt
Explanation
Introduction / Context:Hysteresis in a Schmitt trigger defines the voltage band that prevents chatter by requiring a different threshold for rising versus falling transitions. This problem is a straightforward computation.
Given Data / Assumptions:
- Rising threshold VT+ = 2.0 V.
- Falling threshold VT− = 1.2 V.
- Hysteresis is the absolute difference between thresholds.
Concept / Approach:The hysteresis width is VT+ − VT−.
Step-by-Step Solution:
Compute: VH = VT+ − VT− = 2.0 − 1.2 = 0.8 V.Interpretation: Input must move 0.8 V across the band before the output can toggle back.Verification / Alternative check:Check signs: thresholds are ordered VT+ > VT−, so difference is positive.
Why Other Options Are Wrong:
- 0.4 volt / 0.6 volt: Underestimates the difference.
- 1.2 volts: Confuses with the lower threshold magnitude.
Common Pitfalls:Adding thresholds instead of subtracting, or using an average rather than the difference.
Final Answer:0.8 volt