Compact frequency-divided micro-electromechanical systems tunable filter using inductively coupled structure

A fully-integrated frequency-divided tunable filter was newly designed and fabricated using an inductively coupled structure with lumped elements and MEMS fabrication technique. The inductively coupled structure allows for the size of the filter to be reduced, and electro-mechanically switched capacitors were used to obtain the tunability of frequency. When the proposed filter operated without using the switched capacitors, it exhibited insertion and return losses of 2.5 and 8 dB, respectively, in a single, wide passband with a range from 3.5 to 6 GHz. Otherwise, when the proposed filter operated with the use of the switched capacitors and a DC voltage bias of 30 V, a dual passband was formed at frequencies of less than 4.5 GHz and more than 5.5 GHz. Its size/volume was 3.3 × 1.7 × 0.535 (H) mm³.