S-band Band-pass Filter by Using Integrated Passive Device Technology

The micro integration of passive components such as filters is one of the important problems faced by system in package (SiP). Thin-film integrated passive device (IPD) technology provides an effective solution for the minimization. In this paper, the design, fabrication and measurement of the S-band band-pass filter has been investigated by GaAs based thin-film IPD technology. Firstly, by using lumped circuit model, it can be determined the topology structure of the filter and obtain the schematic diagram to meet the specific requirements of the filter. Secondly, the filter is fabricated by using thin film IPD-PI processing, which includes the Wafer Front Side process and the Wafer Backside process on GaAs substrate. Finally, the performance of the filter is tested by using the probe and vector network analyzer. The maximum insert loss in band is 3.0 dB at 3GHz, the lower suppression out of band is 34.7dB at 1.2GHz and the upper suppression out of band is 28.6dB at 3.6GHz, which meets the requirements of designed s-band band-pass filter. The test results and simulations are very close which means the filter designed and fabricated by thin-film IPD technology has quite good accuracy. The S-band band-pass filter by IPD technology greatly reduces the size and weight compared with traditional discrete devices, improves the system integration, and provides the basis for the implementation of highly integrated RF front-end.