New Generation of AD-measurement Cards for High Accuracy Measurements
Schnabel, R. Kuenzi, Felix Jenni, Heinz Jäckel, M. Emmenegger · Presented at · 2008
Current transducers are, together with the AD conversion of the current signal, the key elements of high precision power supplies. The accuracy of commercially available current transducers is within the range of a few pp m. Any degradation of this precision by the succeeding stages must be kept as small as possible. Therefore, the accuracy of the AD conversion has to be at least in the same order of magnitude. Under stable conditions, the accuracy can be improved by measuring and correcting the miscellaneous errors of the ADC and the involved components, such as voltage reference, antialiasing filter and input amplifier. From the measured deviation data a correction look-up table can be derived and later processed. Further provisions like temperature stabilization, galvanic isolation, electromagnetic shielding, fully differential signal paths and generally a low-noise design allow for further improvements in respect to stability and accuracy.