ERREURS ANALOGIQUES DANS LES CAN A BANCS DE FILTRES HYBRIDES
'Méthodes d'estimation et nouvelles structures'

摘要

Hybrid Filter Bank (HFB) A/D converters are a good candidate for realizing the future versatile, intelligent and wide-band communication systems. However, the HFB structures exhibit a large sensitivity to the analog non-idealities of analysis part so that the classical HFB ADCs are not practically useful unless these errors are corrected. The efforts have been made in this thesis to more profoundly study this problem and to propose a group of possible solutions. Firstly, the design phase of related HFBs is described in the matrix form. Considering the simply realizable first- and second-order analog circuits as analysis filter bank and FIR digital synthesis filters, the HFB structures are designed for A/D conversion in this thesis. Simulating some exemplary HFB ADCs, it is shown that the sensitivity of HFB to analog errors is so large because the related analysis matrix is ill-conditioned, particularly in the case of oversampling process. Using Second-Order and Higher-Order Statistics, it is shown that the analog imperfections of analog circuits may digitally be estimated through the output samples. However, these techniques appear not to be applicable to the conventional HFB structure because of undersampling process included at each branch of HFB-based ADC. Thus, for exploiting the digital techniques to estimate and then correct the analog imperfections of analysis filter bank, new Multiple-Input Multiple-Output (MIMO) HFB structures are proposed so that there exist no under-sampling operation anymore between the related input-output signals. The simulations show that the MIMO (TDM and subband) HFB architectures provide not only a better output resolution but a less sensitivity to the realization errors of analysis filter bank than the classical HFB. Finally, using the TDM and subband MIMO HFBs, it is proposed to use the blind methods such as blind deconvoluton or Automatic Noise Cancelation (ANC) for compensating and then reducing the sensitivity to the analog non-idealities.