Two-input two-output current-mode universal biquad using only VDTAs and grounded capacitors

A two-input two-output current-mode universal biquad employing only two voltage differencing transconductance amplifiers (VDTAs) and two grounded capacitors is introduced. By appropriately connecting the input and output terminals, the proposed circuit can realize lowpass, bandpass, highpass, bandstop and allpass current responses. It also exhibits an independent electronic control of the natural angular frequency (ωo) and the quality factor (Q) by properly setting the transconductance values of the VDTAs. No critical component matching choices are imposed for generating all the filter functions, and all incremental parameter sensitivities are low.