Design of compact microwave filter using vertically interdigitated resonators

A compact low temperature co-fired ceramic (LTCC) filter using vertically interdigitated resonators is realized in this paper. Multilayer vertically interdigitated capacitors (VICs) and a metal strip inductor are connected in parallel to implement the proposed vertically interdigitated resonator (VIR). The proposed bandpass filter is designed at center frequency 2.45 GHz with 8% fractional bandwith. This filter has not only a compact physical size 1.75 × 0.983 × 0.963 mm³ but also a compact electrical size 0.039 × 0.022 × 0.021 λ_g³. The measured insertion loss of the realized filter is about 2.1 dB and in-band return loss is greater than 14 dB.