Modified single point calibration with improved accuracy in direct sensor-to-microcontroller interface

A simple sensor-to-microcontroller interface with improved accuracy is described. The sensor interface is based on single point calibration and uses one additional resistor to reduce the overall systematic errors. The errors are reduced by a systematical approach to control the nonlinearity of the transfer characteristic in such way that the system acts as it uses a two point calibration. In the paper, a theoretical model for implementation of the modified single point calibration technique is presented. When analyzing the measurement range typical for PT1000 temperature sensor, the systematic errors reduce by than a factor of two depending on the width of the measurement range. Different theoretical and experimental aspects for implementation of the proposed calibration technique are considered, as well as: process, voltage, temperature variation and power consumption.