Lumped-element equivalent circuit models for multilayer ring resonators filters

Cascaded block filters are proposed for ultra-wideband (UWB) applications. This class of microwave bandpass filters (BPF) is based on multilayer ring resonators (MRR) structure. The novelty of this configuration, with respect to MRR, is to improve the selectivity of the filters and introduce high order super-compact circuits. For the first time, lumped-element equivalent circuit models are introduced for both MRR structures and cascaded block filters. The mathematical model derived from the lumped circuit shows a close match with the filters frequency responses. Admittance matrix is derived and given for the analysis. Low-temperature co-fired ceramic (LTCC) is a suitable technology to implement these types of filters. Various prototypes are introduced and their frequency responses are demonstrated using electromagnetic simulation software.