Nonlinear systems can introduce this unwanted effect.

• A. Distortion
• B. Attenuation
• C. Phase Shift
• D. Noise

Answer: (A)

Nonlinearity means the output isn’t a scaled version of the input. When a nonlinearity processes a signal, it generates new frequency components—harmonics and, with multiple tones, intermodulation products—so the waveform is reshaped. That change in the waveform’s shape is what we call distortion, the unwanted effect of a nonlinear system. Attenuation is simply a loss of amplitude and can happen for many reasons, not specifically tied to nonlinearity. Phase shifts can occur in linear systems as well and don’t by themselves deform the waveform. Noise is random energy; while nonlinear systems can interact with it, the distinctive consequence of nonlinearity is distortion from the added frequency content.