Patent ID: 7841238

Claim:
A pressure sensor that compensates for temperature variations, the pressure sensor comprising: CMOS layers deposited on a substrate; a conductive layer deposited on the substrate and connected to the CMOS layers; a passivation layer deposited on the CMOS layers; a conductive active membrane spaced from the conductive layer to form an active chamber, and a conductive reference membrane spaced from the conductive layer to form a sealed reference chamber; a cap which covers the membranes, said cap exposing the active membrane to an outside fluid pressure, said active membrane further defining a foot which is located between the substrate and cap with a leg extending away from the substrate and terminating in a substantially planar deflectable portion, which deflects due to differential pressure stresses so that an active capacitance is developed between the active membrane and the conductive layer depending on the electrical permittivity e of the fluid, with the reference membrane providing a temperature compensating reference capacitance; and sensor circuitry configured to determine a charge imbalance indicative of a pressure difference between the active and reference membranes.