Intelligent CMOS control of RF MEMS capacitive switches

A CMOS control circuit capable of closed-loop capacitance sensing and control of RF MEMS switches was designed, fabricated, and tested. The control was based on fine-tuning the magnitude of the bias voltage of the switches according to the difference between sensed and targeted capacitances. Intelligence could be programmed by periodically alternating the sign of the bias voltage when its magnitude to maintain the targeted capacitance drifted significantly due to dielectric charging. Such an intelligent control could also be used to compensate for process variation, ambient temperature change, and RF power loading, which would make RF MEMS capacitive switches not only more reliable, but also more robust.