An optimised differential topology of an RF active filter and its performances are presented. It makes use of two negative resistances in order to independently tune the central frequency and the quality factor. The differential active filter is designed in a 0.18 µm CMOS process, allows a maximum wide range of tunability between 1.6 and 2.6 GHz and exhibits high quality factor values with a maximum power consumption of 0.6 mW. The principle seems to be sufficiently general to be used for other active filters single–ended or differential topologies based on simulated inductors.

Keywords: Active filters, Negative resistance, Simulated inductor