Analysis of Micromachined Capacitive Incremental Position Sensor

 This article presents an analysis for two related concepts of a capacitive incremental position sensor. In Incremental Capacitance Measurement Mode the periodic change in capacitance is measured to determine the relative displacement between two periodic geometries S1 and S2 with gap-distance of ~ 1 μm. In Constant Capacitance Measurement Mode the distance between S1 and S2 is controlled to keep the capacitance between S1 and S2 constant. Analysis and 2DFinite Element simulations show that SNR for CCMM can be >300x over ICMM and with a lower non-linearity in the position sensor signal, CCMM will perform better in accurate quadrature position detection.