Abfallzeit

Abfallzeit, in German electronics terminology, refers to the fall time of a signal—the time required for a waveform or output to decrease from a high level to a low level. It is a characteristic of how quickly a circuit or component can turn off or transition from a high to a low state, and is commonly discussed alongside the rise time (Anstiegszeit).

In practice, Abfallzeit is typically defined operationally as the time needed for the signal to fall from 90 percent to 10 percent of its peak amplitude. This convention, along with the measurement setup, probe type, load impedance, and drive strength, is specified in datasheets and measurement standards. The parameter is especially relevant for digital switching, pulse shaping, and high-speed communication networks.

The Abfallzeit is closely related to the system’s bandwidth and overall speed. Shorter fall times indicate faster edge transitions and higher potential data rates, but can also increase noise, ringing, and electromagnetic interference. For simple single-pole responses, fall time is roughly inversely proportional to the bandwidth, so improvements in bandwidth typically reduce Abfallzeit.

Outside electronics, the term Abfallzeit can be encountered in a broader sense to describe a decay process in physics, where a quantity diminishes over time with a characteristic time constant. In such contexts, more common terms are decay time or lifetime; Abfallzeit is less specific and may be used informally.

See also: rise time, bandwidth, signal integrity, decay time.