Patent ID: 7714591
Filing Date: 2010-05-11
Classification: G01L

Abstract:
1. A pressure sensing apparatus comprising: at least one deflectable diaphragm having a center, wherein each diaphragm supports: at least one positive piezoresistive gauge and at least one negative piezoresistive gauge coupled in series across a voltage differential in a half-Wheatstone bridge configuration having an output between said positive and negative piezoresistive gauges; and, a compensating negative piezoresistive gauge coupled in series with the half-Wheatstone bridge configuration across the voltage differential, wherein, the compensating negative piezoresistive gauge is positioned nearer the center of the diaphragm, an area of substantially higher differential stress, than the negative piezoresistive gauge, and the negative piezoresistive gauge is positioned nearer the center of the diaphragm than the positive piezoresistive gauge, wherein said negative piezoresistive gauge and said positive piezoresistive gauge are positioned in regions that experience substantially equal and opposite stresses, and said position of said compensating negative piezoresistive gauge is determined to linearize an output of the half-Wheatstone bridge, wherein a value of said compensating negative piezoresistive gauge is based on a ratio of values of said negative piezoresistive gauge and said positive piezoresistive gauge.