Self-balanced high-resolution capacitive microaccelerometers using branched finger electrodes with high-amplitude sense voltage

This paper presents a high-resolution capacitive microaccelerometer, whose low-noise self force-balancing effect has been achieved by using branched finger electrodes with high-amplitude anti-phase sense voltage. We reduce the mechanical noise of the microaccelerometer to the level of 5.5 /spl mu/g//spl radic/(Hz) by increasing the proof-mass based on the deep RIE process of an SOI wafer. We reduce the electrical noise as low as 0.6 /spl mu/g//spl radic/(Hz) by using an anti-phase high-amplitude square-wave sense voltage of 19 V. The nonlinearity problem arising from the high-voltage capacitive detection has been solved by a new electrode design of branched finger form. Combined use of the branched finger electrode and the high-amplitude sense voltage has generated self force-balancing effects, resulting in a good linearity of 0.044% with an 140% increase of the bandwidth from 726 Hz to 1.734 Hz.