Using a low-voltage VHF CMOS active inductor, based on the exploitation of the intrinsic device capacitance, a compact tuneable 2<sup>nd</sup>-order RF bandpass filter is realised by adding a series capacitor to the input port of the inductor. This approach renders a simple realisation of a high-order RF bandpass filter, required for its enhanced image rejection ability, by coupling the 2<sup>nd</sup>-order stages. Second- and fourth-order fully differential filters are realised in a 0.35 μm CMOS process, and HSPICE simulations show that the filters can operate at the 2.4 GHz ISM frequency band under a 2 V power supply voltage with power dissipation less than 0.9 mW/pole.
