Low voltage low power CMOS inductorless RF bandpass filter with high image rejection capability

A new design approach suitable for realising low-power low-voltage high-order RF bandpass filter is proposed. Using a low-voltage VHF CMOS active inductor based on the exploitation of the intrinsic device capacitance, a compact tuneable 2nd-order RF bandpass filter is realised by adding a series capacitor to the input port of the inductor. The proposed 2nd-order filter can be readily cascaded to realise a high-order filter with enhanced image rejection ability. High-Q second-, fourth- and sixth-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 about 1 mW power dissipation per pole.