Design and Research of MEMS-Based Double-Layer Silicon Filters

Based on the interdigital structure, a microwave S band interdigital bandpass filter was proposed using silicon MEMS technology. While retaining the interdigital structure, the desired return loss was achieved by adjusting the distance between the vias and the resonator rods. Two filters were designed. The first filter has a center frequency of 21.4 GHz, a 1 dB bandwidth exceeding 2.5 GHz, an insertion loss of less than 1.5 dB, and a return loss greater than 15 db. Additionally, it achieves a stopband attenuation of more than 50 dB at frequencies of $\mathrm{f}_{\mathbf{0}} \pm 1.4 \mathrm{ghz} \mathrm{GHz}$. The filter’s compact dimensions are $(7 \times 2.8 \times 0.804) \mathrm{mm}^{3}$. The second filter has a center frequency of 5.5 GHz, a bandwidth of 1 GHz, an insertion loss of 2 dB, and a return loss exceeding 15 db. Its compact dimensions are also $(7.4 \times 5.9 \times 0.804) \mathrm{mm}^{3}$.