Current-mode universal filter using unity gain cells

A new universal current-mode biquad filler circuit suitable for integrated circuit implementation is presented. The circuit uses three two-output curr ent followers, two voltage buffers, two grounded capacitors and four virtua lly grounded resistors to realise all the standard biquad filters without c hanging the circuit topology. The proposed circuit can be used to achieve i ndependent control of the natural frequency and the bandwidth. Also, the fi lter exhibits a low input impedance, high output impedance as well as low a ctive and passive sensitivities. Simulation results using CMOS unity gain c ells are also presented.