INTEGRATED SMART SENSOR CALIBRATION

In many applications electronic sensors are used to improve performanc e and reliability of measurement systems. Such sensors should provide a correct transfer from the physical signal to be measured to the elec trical output signal. One important step to achieve this, is to calibr ate each sensor by applying different reference input signals and adju sting the sensor transfer accordingly Besides expensive reference equi pment the calibration process takes much time and attention per indivi dual sensor, which means a considerable increase in sensor production costs. By including at the sensor or sensor interface chip a programma ble calibration facility the calibration of such smart sensors can eas ily be automated and can be executed for a batch of sensors at a time, thus minimizing the calibration time and costs. This paper presents a calibration method and options for integration in the smart sensor co ncept, in hardware as well as in software. An advantage of the propose d method is that it does not need a large matrix of calibration data, which needs to be stored in a look-up table or converted into a correc tion formula, but instead it uses a step-by-step approach to correct t he sensor transfer at each calibration measurement until the error is sufficiently small.