Just as filters introduce amplitude ripple in the passband, many also have phase variations across the passband and in the transition band. The effect of a non-flat phase response in a filter is to cause the various frequency components that make up the data signal to undergo slightly different amounts of phase shift. If the phase response is not flat, or does not increase linearly with frequency (termed a linear phase response), distortion will be introduced into the time waveform of the data pulse or symbol as shown here. If the component has a linear phase response, this translates into a fixed time delay of the signal passing through it, but otherwise the signal will not be distorted. |
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