Post-Correction of Analog-to-Digital Converters
2003 (English)Report (Other academic)
This thesis deals with digital post-correction of analog-to-digital converters (ADCs). The performance of practical ADCs is deteriorated by non-idealities and flaws in the converter. Methods for mitigating these errors by applying digital signal processing to the output of the converter have been proposed in the past. These methods are often referred to as post-correction methods. This work is mainly concerned with post-correction methods based on look-up tables. Practical ADCs often exhibit dynamical error behavior, meaning that the error is dependent on the dynamics of the input signal. In this thesis an extension of previously proposed post-correction methods is proposed. The method uses the present sample in conjunction with a number of past samples to form the table index. In order to reduce the number of index bits, and thereby the size of the table, the method comprises a ‘bit mask’, which selects a subset of the available bits to be used in the index. Evaluations using experimental ADC data show that the proposed method improves the converter performance, but also that the choice of index bits has a significant impact on the outcome of the correction. The incorporation of a bit mask enables an analysis of the effect of different bit masks. The analysis results in a framework for comparing different correction tables. The framework is then applied in an optimization problem. The goal is to find the best allocation of a fixed number of index bits. Two different criterions are applied: minimization of the total harmonic distortion and maximization of the signal-to-noise and distortion ratio. The results of the optimization, performed with experimental data, show that the optimal bit allocation is different depending on which criterion is used. Moreover, the performance of a correction scheme deteriorates only slowly with decreasing table size, if appropriate index bits are selected.
Place, publisher, year, edition, pages
Royal Institute of Technology (KTH) , 2003.
post-correction, analog-to-digital converters
IdentifiersURN: urn:nbn:se:kth:diva-96556OAI: oai:DiVA.org:kth-96556DiVA: diva2:531271
Licentiate Thesis NR 201408052012-06-062012-06-062012-06-06Bibliographically approved