Testing IC accelerometers using Lissajous compositions

Abstract

Micro Electro Mechanical devices (MEMs) have widened their range of applications in a spectacular way in the last years. Reliability of MEMs devices is one of the areas that need to be improved to achieve high volume production at allowable costs. Accelerometers have in their design some mechanical and layout symmetries that can be used to improve the test and diagnosis results. In our approach we take profit of the symmetries of dual axis accelerometers to analyze and test its behavior using a procedure that composes the two orthogonal outputs when the accelerometer is spun. The complexity in the kinematics seen by the sensitive axes of the accelerometer yields rich and complex Lissajous traces that characterize the device and allows to determine the possible mismatchings in the assumed damped mass model parameters. In order to compare and quantify parameter discrepancies, a metric has been defined to allow to determine whether the DUT is within specifications or not.