A transient change in voltage, current, or some other normally constant physical parameter. This transient consists of a transition from one level to another, followed, after a fixed time, by an opposite and often equal amplitude transition. The first edge to occur on a pulse is the leading edge, the second transition being the trailing edge.
For rectangular pulses the transitions should in theory be stepwise, i.e. instantaneous. In reality however they require a finite time in which to occur. For transitions from low to high voltage, current, etc., a convenient measure of this time is the rise time, defined as the time required for the pulse amplitude to rise from 10% to 90% of its maximum value (see diagram). The fall time is the time interval between the 10% point and the 90% point on the negative-going edge of the pulse.
The time interval between the leading and trailing edge of a rectangular pulse is called the pulse width. The pulse height is the amplitude of a pulse, usually its maximum to minimum voltage, current, etc., ignoring any short-duration spikes or low-amplitude ripple superimposed on the main pulse. See also ringing.
Pulse. Rectangular voltage pulse