High temperature pressure sensor with monolithically integrated CMOS readout circuit based on SIMOX technology

An integrated capacitive surface micromachined pressure sensor for high temperature applications was developed and characterized to work at temperatures up to 250 degreesC. The sensor and the CMOS readout circuit are processed on SIMOX (Separation by IMplantation of OXygen) substrates. The readout circuit is programmable and allows calibration of linearity, offset and output range. The performance of a 20 bar and a 50 bar sensor is discussed. Even without active temperature compensation the offset temperature coefficient referred to full scale output (FSO) is less than 0.03 %/degreesC between 25 degreesC and 150 degreesC and less than 0.09 %/degreesC between 150 degreesC and 250 degreesC. The linearity error is less than 0.4 % FSO.