Which statement describes a sawtooth wave?

Which statement describes a sawtooth wave?

• A. Rise and fall times are equal.
• B. Rise and fall times are unequal, with one edge possibly instantaneous.
• C. The waveform is a rectangular pulse with fixed width.
• D. The waveform is a pure sine wave.

Answer: (B)

A sawtooth wave is characterized by an abrupt transition in one direction and a gradual, linear ramp in the other. In the typical form, the signal rises smoothly over a finite rise time and then abruptly drops back to the starting level (or vice versa), so the rise and fall times are not equal and one edge can be essentially instantaneous. That is exactly what the statement describes: rise and fall times are unequal, with one edge possibly instantaneous. This differs from a sine wave, which has smooth, continuous cycles with no sharp edges; and from a rectangular pulse, which has two sharp edges and a fixed width. A triangle-like waveform would have equal rise and fall times, which is not sawtooth.

A sawtooth wave is characterized by an abrupt transition in one direction and a gradual, linear ramp in the other. In the typical form, the signal rises smoothly over a finite rise time and then abruptly drops back to the starting level (or vice versa), so the rise and fall times are not equal and one edge can be essentially instantaneous. That is exactly what the statement describes: rise and fall times are unequal, with one edge possibly instantaneous.

This differs from a sine wave, which has smooth, continuous cycles with no sharp edges; and from a rectangular pulse, which has two sharp edges and a fixed width. A triangle-like waveform would have equal rise and fall times, which is not sawtooth.