Design and fabrication of 2.45G miniaturized band pass filter by LTCC technology

With the rapid development of wireless communication systems and personal consumer electronics, it is intensely necessary for RF-products to be more and more multifunctional and miniaturized. The low-temperature co-fired ceramics (LTCC) technology which has 3-D integration capabilities and low cost is usually used to fabricate miniaturized multilayer RF passive components. As one of the most important passive components in RF wireless transceiver system, the band pass filter (BPF) has attracted significant interest in 3-D miniaturized design. [1, 2]. As we known,an excellent BPF must have low pass-band insertion loss and large out-of-band rejection. In this paper, a 2.45G miniaturized band pass filter, which incorporates a feedback capacitor between input and output to realize two finite transmission zero has been optimized by Ansoft HFSS. After the physical model and inner structure of the BPF are established, the samples are fabricated by LTCC technology. Testing results show that the insertion loss is less than 5.2dB and return loss is less than -13dB at the center frequency of 2.6GHz, which agree basically with the simulation results.