Patent ID: 7437187

Claim:
A filter comprising: (a) a dielectric substrate having a top surface and a bottom surface; (b) a ground plane comprising a layer of conductive material provided on the bottom surface; and (c) a plurality of resonators, each resonator being arranged to receive a signal from an input end and transmit a signal to an output end, and each resonator comprising (d) an inductor provided on the top surface and connected to the input and output ends; and (e) a series capacitor connected in parallel to the inductor, wherein the series capacitor comprises two patches of conductive material provided on the top surface, each patch being connected to one respective end of the resonator, wherein each patch forms a shunt capacitor with the ground plane, and the capacitance of the respective shunt capacitor constitutes at least part of capacitance between the ground plane and the end of the resonator that is connected to the corresponding patch, and wherein the series capacitor is sufficiently capacitive, in the absence of a biasing voltage, to reduce cross-coupling between non-adjacent resonators.