Patent ID: 8393222
Filing Date: 2013-03-12
Classification: G01L

Abstract:
1. An absolute piezo-resistive pressure sensor system comprising: a single wafer having respective first and second cavities etched therein forming respective first and second deflectable membranes serving as respective first and second pressure sensing elements; the first deflectable membrane having an aperture defined therethrough, while the second deflectable membrane does not; a first surface of each of the first and second deflectable membranes being exposed to a pressure within the respective first and second cavities; an opposing second surface of each of the first and second deflectable membranes being enclosed in a common hermetically sealed chamber formed by a cover assembled to the single wafer, wherein a pressure within the chamber is substantially constant; a piezo-resistive material is assembled to the opposing second surface of each of the first and second deflectable membranes subject to the same pressure within the sealed chamber; a base plate having a single hole defined therein; the wafer being assembled to the base plate with the hole substantially aligned with the second pressure sensing element; and electronic circuitry for: (i) simultaneously while detecting using the second pressure sensing element a pressure in the second cavity, calibrating a measured offset voltage detected by the first pressure sensing element due to mechanical stress release at an assembly interface between the wafer and the base plate; and (ii) compensating the pressure in the second cavity detected by the second pressure sensing element based on the offset voltage as calibrated by the first pressure sensing element.