Abstract: A silicon pressure sensor includes a bossed diaphragm provided with a planar surface. The bossed diaphragm converts a pressure applied to the planar surface to a force, and transmits the force through a central boss to a sensing diaphragm positioned next to the bossed diaphragm. The sensing diagram converts the force to an electrical signal. To fabricate the sensor, both diaphragms are formed in large numbers on silicon wafers and then bonded together before being separated as individual, complete sensors.

Abstract: A Wheatstone bridge circuit for a strain gage designed to eliminate the zero offset due to heated cables occurring when the active elements of the bridge circuit are elevated to high temperatures. The bridge circuit comprises an active, a dummy and two completion resistors and is distinguished from conventional bridge circuits in that the resistance of the completion resistors substantially exceeds the value of any other resistors in the bridge circuit. The cables are used to connect the active and dummy resistors which are at the elevated temperatures to the completion resistors which are at room temperature. Heat induced resistance changes in the cables normally produce the zero offset because the cables form a part of the bridge circuit and are heated unevenly; however, the high value of completion resistors incorporated in the present invention tend to nullify the resistance changes in the cables and thereby eliminate the zero offset.

Abstract: A measurement circuit and calibration technique for temperature compensating a half-bridge-high-temperature strain gage, capable of providing data which is independent of cable resistance variations.The need for a compensating resistor is eliminated and the cable conductors are removed from the measurement circuit. The output signal is easily and accurately converted to a measurement of strain without the need for auxiliary measurement required with prior art circuitry.