Op amp second order filter circuit

Aguilera

Op amp second order filter circuit [Copy link]

There are two structures of second-order filter circuits: Sallen-key and multi-feedback (KFB) A%20=%201+R4/R3 The basic circuit of the MFB filter is shown in the figure below. This circuit has two negative feedback branches, and the operational amplifier is used as an infinite gain device to feedback the branch, and the operational amplifier is used as an infinite gain device, so it is called an infinite gain multi-terminal feedback circuit. A%20=%20-R2/R1 High-pass filtering: %20Replacing the resistor of the low-pass filter with a capacitor, and then replacing the capacitor of the filter with a resistor, you can produce a high-pass filter. A = 1+R4/R3 A = -C2/C1 Basically there are 4 types of active filters. They are Butterworth, Bessel, Chebyshev and Elliptic filters.