Low input impedance current-mode active filter using current-followers

This paper presents a topology for a second-order current-mode active filter based on current-followers. Compared to other similar circuits presented in literature, the new topology provides low input impedance that makes possible the connection in cascade of two or many similar circuits without additional current buffers. Hence the circuit uses only two current followers and a reduced number of passive components: two capacitors and two or three resistors, depending on the required transfer function. By choosing appropriate values for the circuit´s admittance it is possible to achieve the three most important transfer functions: low-pass, high-pass and band-pass.