Relative media pressure compensation technique using rectangular diaphragms

A novel compensation design that significantly improves the accuracy of O-ring packaged silicon MEMS differential pressure sensors, is presented. The work focusses on eliminating the overall relative media pressure dependency of O-ring packaged MEMS pressure sensors. The presented sensor is based on a rectangular micromachined diaphragm with piezoresistive elements implanted near the diaphragm edges and center. The resistors are interconnected in a Wheatstone bridge configuration with each quadrant consisting of series connected resistors from the diaphragm center and edge. Using this simple approach, the relative media pressure dependency of O-ring packaged MEMS pressure sensors are reduced from maximum 1.5% to maximum 0.4% of the overall sensor output. This shows the significant improvement in differential pressure sensor accuracy using the developed sensor. Furthermore, the temperature dependency and various application aspects of the sensor design is presented and analyzed in detail. All through the work the findings are supported by 3D FE stress analysis.