Abstract: A dual-element, parallel-plate silicon capacitative pressure sensor includes a pressure sensing element and a reference element of identical structure. Both elements are separately fabricated from the same silicon wafers using identical processing steps. Further, both elements are simultaneously mounted to a header using identical mounting steps. Such identical fabrication and mounting steps serve to identically match the dielectric materials and, thus, the aging properties of both the sensing and reference elements. By matching the sensing and reference elements in these ways, and by aging these components at elevated temperatures in exactly the same way, it is possible to achieve an extremely close match in long-term dielectric aging properties.