Two new configurations for the design of biquad filters with high input impedance are presented. The first configuration can synthesize low-pass and high-pass filter functions according to the passive components used. The second one can synthesize a band-pass filter function. The proposed configurations employ only one differential difference current conveyor (DDCC) as active elements and minimum number of passive elements, namely two resistors and two capacitors. Another filter topology based on DDCC is presented that allows modifying the quality factor without changing its natural frequency. All the filters enjoy low sensitivities. SPICE simulation results are given to confirm the validity of the analysis and to point out the high performance of the filters.