A Silicon-Based Self-Shielded MEMS Bandpass Filter

Basing on coupling coefficient technique and micro-electro-mechanical-system (MEMS) fabrication techniques such as silicon deep reactive ion etching (DRIE), surface metallization and thermal pressed Au-Au bonding, process flows of a self-shielded double-layer interdigital bandpass filter was developed, and a prototype bandpass filter of its kind with open circuit type cross finger structure to be applied to C band was successfully fabricated and tested. Measurement results show that, the center frequency is 3.96 GHz; the frequency error is 2.6%; the insertion loss is 4 dB; the voltage standing wave ratio (VSWR) is below 1.2; the relative is 20.7%; size of the filter device is 7.0 mm×7.8 mm×0.8 mm and the weight is less than 0.1 g. The proposed bandpass filter possesses the advantages of small size, light weight, high performance, low cost, easy to be integrated and being able to be batch produced, adapting to the needs for miniaturization, weight reduction and monolithic integration of filters in microwave and millimeter wave circuits and systems.