A direct digital converter that provides a digital output, proportional to the measurand being sensed by a single active element resistive sensor is presented in this paper. To accomplish this task, the structure and the switching sequence of a conventional dual slope, analog to digital converter (DSADC) is appropriately altered so that the altered DSADC accepts the resistance of the sensor as an integral part and provides a digital output that is linearly proportional to the physical quantity being sensed by the resistive sensor. Since the output of the dual slope resistance to digital converter (DSRDC) is dictated only by the magnitudes of a pair of DC reference voltages, a fixed value resistor and the transformation constant of the sensor, the error in the output is minimal. Hence, a high level of linearity and accuracy is achieved. Simulation studies establish the efficacy of the proposed scheme.
Dr. Madhu Mohan N. and V. Kumar, J., “Direct digital converter for a single active element resistive sensor”, in 2009 IEEE Instrumentation and Measurement Technology Conference, 2009.