HIGH FREQUENCY PULSE WIDTH MODULATION DRIVER PARTICULARLY USEFUL FOR ELECTROSTATICALLY ACTUATED MEMS ARRAY

摘要

Pulse-width modulation (PWM) drive circuitry particularly applicable to an array of electrostatic actuators formed in a micro electromechanical system (MEMS), such as used for optical switching. A control cell associated with each actuator includes a register (222) selectively stored with a desired pulse width. A clocked counter (220) distributes its outputs to all control cells. When the counter matches the register, a polarity signal corresponding to a drive clock is latched and controls the voltage applied to the electrostatic cell. In a bipolar drive, one actuator electrode is driven by a drive clock (CLK); the other, by the latch (228). The MEMS element may be a tiltable plate supported in its middle by a torsion beam. Complementary binary signals may drive two capacitors formed across the axis of the beam. The register and comparison logic for each cell may be formed by a content addressable memory.