Design and Fabrication of Silicon-cavity Band-pass Filters Based on MEMS Technology

Microwave filter is an important frequency selective component in communication, radar and other microwave systems, and its performance will directly affect the performance of the whole system. With the miniaturization, lightweight and intelligence of microwave systems, the miniaturization, integration and high performance of filters are the main development targets. This paper introduces the design and fabrication of C-band silicon cavity filters based on the interdigital resonant structure and Microelectromechanical systems (MEMS) fabrication technology. The silicon MEMS cavity filters, with 1/4 wave length interdigital resonators and tapped input and output lines, are designed and fabricated on high-resistivity silicon substrates. The filter is designed by formulas and HFSS simulation. Test results show that, the filter center frequency is 5.6 GHz, the relative bandwidth is 16%, the insertion loss is 2.04 dB, the inhibition at 4.0 GHz and 6.9 GHz is both greater than 40dB, the voltage standing wave ratio (VSWR) is less than 1.30, and the filter chip size is only 7.3 mm×6 mm×0.82 mm. Also, the test results have high consistency with simulation results.