Circuit arrangement of an active filter

摘要

In order to suppress to a great extent the background noise of an active filter, according to the invention the input signal is fed via the input (1) directly to the input (+) of a subtracting stage (4) and via an active filter (5) to the other input (-) of the subtracting stage (4), which forms a differential signal, which passes to the output (3). If the active filter (5) is a low-pass filter, the arrangement acts like a high-pass filter of which the limiting frequency is equal to that of the low-pass filter. <IMAGE>