Design of smart drivers for electrostatic MEMS switches

This paper introduces the design of smart high-voltage CMOS drivers for electrostatic actuators. Smart must be understood as the capability of the driver to deliver the required voltage to close a MEMS switch and to diagnose whether the electrode moves well or not. This way, stuck or broken switches could be easily identified during operation. To implement such an online diagnosis, we propose to equip the driver architecture with a dedicated circuitry that can detect pull-in events. Pull-in corresponds to a rapid change of the actuation capacitance thus producing a charging current peak. The idea is therefore to monitor the charging current, and to track a current peak that could be small with respect to the current that charges parasitic capacitors. In this paper, we propose two different architectures to cancel parasitic capacitance effects. Both are introduced, studied by simulation and implemented on silicon. Complete demonstration is finally performed with an academic prototype of a MEMS switch.