December 30, 2021
The multiple-feedback (MFB) low-pass filter (LP filter) is a second-order active filter. Vref provides a DC offset to accommodate for single-supply applications. This LP filter inverts the signal (Gain = –1 V/V) for frequencies in the pass band. An MFB filter is preferable when the gain is high or when the Q-factor is large (for example, 3 or greater).