An investigation into the effect of the bias line on the insertion loss of RF-MEMS tunable filter

Explicit design formulae to describe the effect of the bias line on the insertion loss of RF-MEMS tunable filter are presented at first in this paper. Afterwards, a five-order RF-MEMS tunable filter using five identical MEMS capacitance networks is designed and simulated to justify the proposed formulae. From the design example, it is seen that the insertion loss of the filter increased from -7dB to -5dB when the resistance of the bias line varies from 1kΩ2 to 8kΩ2. Finally, the bias line with meander-line shape is introduced in this paper to increase the resistance of the bias line.