High‐performance bandpass filter using HTCC stepped‐impedance resonators

Abstract

Here, a novel rectangular bar stripline stepped-impedance resonator (SIR) using the multilayer high-temperature co-fired ceramic (HTCC) technology is constructed for designing a high-performance bandpass filter (BPF) with enhanced design flexibility. The properties of the HTCC SIR are investigated, so that its quality factor ( Q u ) can be improved. In the design process of comb-stripline filter, two transmission zeros (TZs) on both sides of the passband can be synthesised using the equivalent model for enhancing the passband selectivity. Thus, the resultant filter produced by the high dielectric constant material has several advantages, such as low passband loss, high selectivity, and compact size, which are verified by the simulation and measurement. In the demonstration of the fourth-order BPF centred at 2.25 GHz, two TZs are located at 2.05 and 2.54 GHz, showcasing a sharp roll-off. The insertion loss is <;1.8 dB in the passband. The BPF has a smaller size, when compared with the counterparts using other technologies. The occupied area of the BPF is 4.84 × 6.96 mm 2 .