MEMS AD/DA Converters

MEMS analog-to-digital and digital-to-analog converters are proposed using parallel plate electrostatic actuators under bias. Deformable plates supported by springs are used with bias applied voltage which determines the amount of static displacement needed for equilibrium condition. In analog-to-digital arrangement, eight different spring displacements are tapped off the spring corresponding to eight binary decoded voltages. At spring tapped connections, MOS switches are switched on connecting a digital high voltage level at these locations so that when a certain analog voltage is applied on the moving plate of the capacitor, the spring is displaced to one of these locations, enabling different binary voltages to all switches up to that level. The digital binary voltages are fed to an 8-3 priority encoder to obtain the digital value. In digital-to-analog arrangement, the input binary voltage is decoded to different spring locations which correspond to resistances making up a potentiometer circuit for the output analog voltage.