Electronically tunable current-mode universal filter using VDTAs and grounded capacitors

In this paper, an electronically tunable current-mode universal filter with three inputs and one output employing two voltage differencing transconductance amplifier (VDTA) and two grounded capacitors is proposed. The presented circuit can configure to realize all the five standard biquadratic filter functions; lowpass, bandpass, highpass, bandstop and allpass without changing the circuit configuration and needing an external passive resistor. The proposed filter is capable of providing an independent current-control of the natural angular frequency (ωo) and quality factor (Q) through the VDTA's transconductance and low incremental active and passive sensitivities. The performance of the proposed filter is tested using PSPICE simulation program, and the results agree well with the theoretical analysis.