1_kHz_4TH_ORDER_BUTTERWORTH_FILTER

Published:2009/6/19 2:33:00 Author:May | From:SeekIC

The filter is a simplified state variable architecture consisting of two cascaded 2nd-order sections. Each section uses the 360° phase shift around the two op-amp loop to create a negative sum-ming junction at Al's positive input. The circuit has low sensitivities for center frequency and Q, which are set with the following equations:where,The dc bias applied to A2 and A4, half supply, is not needed when split supplies are available.The circuit swings rail-to-rail in the passband making it an excellent anti-aliasing filter for A/Ds. The amplitude response is flat to 1 kHz then rolls off at 80 dB/decade.



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