TEMPERATURE COMPENSATION OF PIEZORESISTIVE PRESSURE SENSORS

A major problem associated with piezoresistive pressure sensors is their cross sensitivity to temperature. The influence of temperature is manifested as a change in the span and offset of the sensor output. Moreover, in batch fabrication, minor process variations change the temperature characteristics for individual units. In this paper, a simulation model for the batch fabrication of piezoresistive pressure sensors is presented. An error band for the sensor response is determined in terms of processing variations for a temperature range of -40 to 130-degrees-C over a pressure range of 0 to 45 psi. Utilizing this information, a new temperature-compensation technique, especially suited for batch fabrication, is described. This technique shows very encouraging results in removing the zero pressure offset and significantly reduces the errors caused by processing variations on the same wafer.