Overshoot (signal)

In signal processing, control theory, electronics, and mathematics, overshoot is the occurrence of a signal or function exceeding its target. Undershoot is the same phenomenon in the opposite direction. It arises especially in the step response of bandlimited systems such as low-pass filters. It is often followed by ringing, and at times conflated with the latter. Maximum overshoot is defined in Katsuhiko Ogata's Discrete-time control systems as "the maximum peak value of the response curve measured from the desired response of the system." In control theory, overshoot refers to an output exceeding its final, steady-state value. For a step input, the percentage overshoot (PO) is the maximum value minus the step value divided by the step value. In the case of the unit step, the overshoot is just the maximum value of the step response minus one. Also see the definition of overshoot in an electronics context. For second-order systems, the percentage overshoot is a function of the damping ratio ζ and is given by The damping ratio can also be found by In electronics, overshoot refers to the transitory values of any parameter that exceeds its final (steady state) value during its transition from one value to another. An important application of the term is to the output signal of an amplifier. Usage: Overshoot occurs when the transitory values exceed final value. When they are lower than the final value, the phenomenon is called "undershoot". A circuit is designed to minimize rise time while containing distortion of the signal within acceptable limits. Overshoot represents a distortion of the signal. In circuit design, the goals of minimizing overshoot and of decreasing circuit rise time can conflict. The magnitude of overshoot depends on time through a phenomenon called "damping." See illustration under step response. Overshoot often is associated with settling time, how long it takes for the output to reach steady state; see step response. Also see the definition of overshoot in a control theory context.