Design of Compact Integrated Lumped-Element Coupled-Resonator Filters

This paper presents a methodology for compact design of integrated lumped-element capacitive-coupled-resonator bandpass filters. The compact footprint is realized based on magnetic flux cancelation between two partially overlapped resonator inductors. Furthermore, parasitic capacitance between the overlapped inductors can be absorbed into the coupling capacitance of the filter architecture. The design methodology is demonstrated for a second-order bandpass filter with 3.5 GHz center frequency and 17% fractional bandwidth. Both standard and compact layout designs in a 180nm SiGe BiCMOS technology are simulated with HFSS. The compact design achieves about a 40% footprint reduction without sacrificing filter performance.