Pre-ringing refers to an inherent character of the impulse response of linear-phase filters employed in D-A or A-D converters. In a conventional analogue or minimum phase filter, an input impulse signal will generate an output impulse response with a strong initial spike followed by a string of ripples of decrasing magnitude. In a linear-phase filter the impulse spike is preceded by a build-up of ripples in advance of the impulse arriving, and a symmetrical string of decaying ripples afterwards.