Very Low Frequency Active Filter Circuit

Published:2011/7/11 3:18:00 Author:Joyce | Keyword: Very Low Frequency , Active , Filter | From:SeekIC

As shown in the figure is a vlf active filter circuit. This is a Butterworth four-order active low-pass filter, which can be used to filter the interference voltage caused by the noise of vlf random pulses on the dc level signal. Its cut-off frequency (-3 dB) is about 8 Hz.When the frequency is 18 Hz, the gain will drop to 20 dB. Natural attenuation within the pass-band is 0.467. And the input resistance is about 40 k Ω. The resistance network of the filter is connected in parallel by several precision resistances with metal film. If the precision of 1μF capacitance reaches a certain amount , the cut-off frequency fc will be close to the theoretical value.



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