State- and Parameter Estimation in Sigma-Delta ADCs by Using Kalman-Filters (SiDeKa)
Various circuit nonidealities of continuous-time Sigma-Delta modulators can drastically reduce the performance of the requested A/D-conversion. Since some of these nonidealities can occur due to manufacturing of the chip or even during run-time, e.g., due to temperature-drift, it is not possible to take account for suppression of those effects already during the design process of the circuit. To restore the original behavior of the converter, it would be desirable to estimate the nonidealities concurrent to the normal system’s operation - with the purpose of immediate compensation.
Unscented Kalman filters are being used in automotive applications for estimating states and parameters of complex and even non-linear systems concurrently in a highly precise and reliable way.
Since the before mentioned circuit nonidealities can be seen as system parameters, the reasonability of the unscented Kalman filter for estimations in Sigma-Delta Modulators is to be investigated in this project. Therefore, the continuous-time Sigma-Delta modulator is optionally fed by binary test signals and its output signal is used as measurement signal for the Kalman filter that iteratively gives better and better insight into the nonidealities of the modulator under test.
Dr.-Ing. M. Lorenz