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The edge steepness is either in electronics or measurement technology


Edge steepness of filters

The frequency response of a filter - no matter what type - is determined by the pass band and the stop band . As can be seen from the designation, all frequencies within the passband should be transmitted as undamped as possible. The attenuation within the stop band, however, cannot take place suddenly with the cut-off frequency for which the filter is calculated, but only sets in gradually. In this way, a transmission curve is created that is as straight as possible in the transmission area and drops more or less steeply towards the blocking area. Filters with 6 dB / oct., 12 dB / oct., 18 dB / oct., Are widely used. and 24 dB / oct.

Particularly straight transmission ranges and steep filter edges can be achieved with quartz and surface wave filters ( AOW filters ).

In the case of typical presence and absence filters with parallel or series resonance circuits, it is not the slope that applies, but only the filter quality .

The slope in dB / oct. However, it is not only to be converted into the quality factor  Q or the bandwidth  B , because there can not be a constant dB / oct. value when increasing or decreasing ( gain ) the center frequency ; see web link below.

Edge steepness of square-wave and switching signals

The edge steepness of signals can not be infinitely high due to the finite limit frequency of the switching elements and transmission elements. It can also decrease due to dispersion along long lines (fiber optic cables, insulated copper cables) or due to low passes .

In many cases, however, it should be or remain particularly high, for example in order to reduce switching losses and to sweep the impermissible (“forbidden”) area of ​​digital circuits as quickly as possible or to guarantee a maximum data rate; see rise and fall times .

Many electronic circuits, such as flip-flops , only function properly if the control pulses have a sufficient edge steepness. This can be increased by using a Schmitt trigger .

However, particularly high edge steepnesses also lead to particularly high interference emissions, since particularly high frequencies then occur in the frequency spectrum of a signal jump, which "couple" more inductively or capacitively, ie. H. can be transmitted from one signal line to another.

Therefore, a compromise must often be made between low switching losses and low interference emissions, for example when controlling switching transistors in switched-mode power supplies .


  • Michael Dickreiter, Volker Dittel, Wolfgang Hoeg, Martin Wöhr (eds.), "Handbuch der Tonstudiotechnik", 8th, revised and expanded edition, 2 volumes, publisher: Walter de Gruyter, Berlin / Boston, 2014, ISBN 978-3- 11-028978-7 or e- ISBN 978-3-11-031650-6

Web links