Mixed-mode filters are useful circuit blocks in modern microelectronic systems applications, such as controls and voice and data communications. In this paper, a mixed-mode biquad filter is proposed providing voltage, current, transconductance and transresistance operating modes. The proposed filter structure only uses a single fully differential current conveyor (FDCCII), two resistors and two capacitors. Moreover, the proposed biquad filter still enjoys,(i) employment only one active element, two capacitors and two resistors, (ii) grounded capacitors and resistors in all modes except voltage mode multi-input single-output filter for proposed filters and (iii) no requirement with the component choice conditions to realize specific filtering functions (iv) no need for inverting amplifiers for special input signals. We performed simulations with SPICE simulation program. Simulation results are found in close agreement with theoretical results.