Electronically tunable current-mode multifunction filter using current-controlled current follower transconductance amplifier

A new electronically tunable current-mode multifunction universal filter with three inputs and one output based on current-controlled current follower transconductance amplifier is presented. The proposed filter can implement low-pass, band-pass, high-pass, band-stop and all-pass transfer functions with a single topology. For implementation of these transfer functions, no passive component-matching conditions, no inverted input signal requirements and high-output impedance are required. Also the proposed filter offers electronic control of the natural angular frequency, low active and passive sensitivities and use of grounded capacitors which is ideal for integrated circuit implementation. The proposed universal biquadratic filter has been used for implementing sixth-order filters. PSPICE simulation results confirm the presented theory.