Universal active current filter with three inputs and one output using plus-type CCIIs

A universal active current filter with three inputs and one output employing only plus-type second-generation current conveyers (CCII+s) is presented. The circuit offers the following advantageous features: orthogonal control of ω_u and Q with one grounded resistor and one virtual grounded resistor, use of grounded capacitors ideal for integration, no requirement of cancellation constraints in realising the lowpass, bandpass, highpass and notch filter responses, low passive sensitivities, high output impedance and simpler configuration due to the use of only plus-type CCIIs