Which statement best describes the waveform components of an ideal triangle wave in steady state?
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Apositive ramps only
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Bnegative ramps only
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Cpositive and negative ramps of equal value
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Dpositive and negative ramps of unequal value
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Ea sinusoid with harmonics only
Answer
Correct Answer: positive and negative ramps of equal value
Explanation
Introduction:A triangle wave is a fundamental non-sinusoidal waveform used in modulation, timing, and function generators. Recognizing its time-domain structure helps in understanding its frequency spectrum and how it is produced by integrator circuits.
Given Data / Assumptions:
- Ideal triangle wave centered around zero with symmetric rise and fall times.
- Constant slope segments (linear ramps).
- No DC offset or asymmetry unless specified.
Concept / Approach:An ideal triangle wave consists of a linear rise followed by a linear fall of equal magnitude but opposite slope, repeating every period. This symmetry leads to a spectrum with only odd harmonics whose amplitudes decrease with the square of harmonic number, but the time-domain hallmark is equal positive and negative ramps.
Step-by-Step Solution:Consider a comparator–integrator oscillator: constant comparator output levels drive the integrator with constant current.Constant current through the timing capacitor causes voltage to change linearly: dv/dt = I/C (constant).When thresholds are crossed, polarity reverses and the slope changes sign but not magnitude.Thus, the output is equal-magnitude positive and negative ramps forming a symmetric triangle.
Verification / Alternative check:On an oscilloscope, measuring rise time and fall time over the same vertical excursion shows equality for an ideal triangle, validating equal ramp magnitudes and durations.
Why Other Options Are Wrong:
- Positive-only or negative-only ramps: Would imply a sawtooth or unipolar waveform.
- Unequal ramps: Produces an asymmetric triangle or sawtooth, not the ideal triangle.
- Sinusoid with harmonics only: Describes a Fourier series perspective but not the direct time-domain ramp description requested.
Common Pitfalls:
- Confusing triangle with sawtooth (which has unequal ramp durations or slopes).
- Ignoring DC offset or duty-cycle variations that break symmetry in real circuits.
Final Answer:positive and negative ramps of equal value