Tunable digital filter arrangement

摘要

A tunable digital filter arrangement realizes the difference equationy[n]= alpha x(x[n]+/-x[n-1])+(1-2 alpha )xy[n-1]and in which the limiting frequency can be tuned linearly by means of only one tuning parameter alpha . The tuning range is limited solely by the sampling rate and bit width of the registers and can also accept in particular very low frequencies. The filter arrangement can therefore also be used in particular for prefiltering sampled and digitized measured values of the motor current for load-dependent motor control in the extremely slow speed range. By selecting "+" as the operator "+/-", a low-pass characteristic results; selecting "-" as the operator results in a high-pass filter. It is possible to cascade several low-pass and/or high-pass filters.