A resonator of a planar circuit type is provided for receiving a signal
from an input end and transmitting a signal to an output end. The
resonator includes: (a) a dielectric substrate; (b) a ground plane
including a layer of conductive material formed on the bottom surface of
the substrate; (c) an inductor formed on the top surface of the substrate
and connected to the input and output ends; and (d) a series capacitor
connected in parallel to the inductor, wherein the series capacitor
includes two patches of conductive material formed on the top surface of
the substrate, each patch being connected to one respective end of the
resonator. Each patch also forms a shunt capacitor with the ground plane,
and the capacitance of the shunt capacitor constitutes the majority of
capacitance between the ground plane and the end of the resonator that is
connected to the patch. The conductive material may be a superconductor,
including oxide superconductors. Filters utilizing multiple resonators of
the invention are also described. The integration of the series and shunt
capacitors results in a more compact resonator and filter layout, allows
broader manufacturing tolerances, and allows for more layout flexibility
than is attainable with the technology of the prior art.