Compact TSV-based wideband bandpass filters on 3-D IC

In this paper, two compact wideband bandpass filters are developed with various operating bandwidths and fabricated on the silicon interposer, which is often used to connect the dies/chips of different functions using 3-D integrated circuit (3-D IC) packaging technique. To fully utilize the advantage of silicon interposer, the proposed filters are designed based on through-silicon-vias (TSVs) to miniaturize the circuit areas. One of the proposed bandpass filters is designed for a single interposer, while the other is for stacked interposers. These compact bandpass filters can be easily integrated with other circuit components and encapsulated into packages without occupying extra circuit areas on PCB. According to the simulated results, at the operating center frequencies of 27.6 and 17.5 GHz, the operating bandwidths can be achieved up to 28 and 43%, respectively; meanwhile, the minimal insertion losses of two bandpass filters are 5 and 6.5 dB at the corresponding center frequencies. The agreement between simulation and measurement is fair. The circuit volumes of single-interposer and stacked-interposer bandpass filters are 1.53 × 0.73 × 0.34 and 0.745 × 0.705 × 0.68 mm³, respectively, or equivalently 0.14 × 0.07 × 0.03 and 0.04 × 0.04 × 0.04 λ_o³, which are respected to the corresponding center operating frequencies.