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ABSTRACT: Hybrid filter bank (HFB) A/D converters (ADCs) are a candidate to realize the wideband ADC for future telecommunication systems. The classical HFB-based ADCs are simulated in both time and frequency domains using simply-realizable analog filters in this paper. The high sensitivity of HFBs to realization errors of an analysis filter bank is studied and it is shown that a new HFB architecture is necessary to employ the blind techniques for correcting the analog imperfections. Using the discrete-time model of HFB, a multiple-input multiple-output (MIMO) model is proposed for the HFB so that a new architecture called subband HFB-based ADC is obtained. The subband HFB ADC not only leads to a better resolution but is less sensitive to realization errors than the classical case. Besides, a linear-time invariant (LTI) system represents the input-output relation of subband HFB without any spectral overlapping in contrary to the classical HFB. Thus, blind techniques may be used for correcting the realization errors in the subband HFB.
IEEE Journal of Selected Topics in Signal Processing 05/2008; · 2.88 Impact Factor
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ABSTRACT: The HFB structure is a suitable candidate to realize a wide-band A/D convertor for the software-defined radio (SDR) systems. Two MIMO time-division multiplexing (TDM) and subband HFB architectures are compared with the classical one in this paper. Simulating in the timedomain, the MIMO HFBs exhibit a better performance than the classical one in terms of output resolution as well as the sensitivity to the realization errors of analysis filter bank. In opposite to the classical HFB case, the MIMO HFBs provide an LTI input-output relation. It is shown that the blind estimation and noise cancelation techniques may be used in the MIMO case for correcting the realization errors. The MIMO and classical HFBs are compared in terms of computational complexity as well.
Signal Processing and Communications, 2007. ICSPC 2007. IEEE International Conference on; 12/2007
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ABSTRACT: In this paper, a new Hybrid Filter Bank (HFB) architecture called Time-Division Multiplexing (TDM) is proposed for HFB-based A/D Converters (ADC). The TDM HFB architecture is firstly extracted considering the TDM components of analog input as new input vector. The TDM HFB-based ADC is then simulated using simply-realizable analysis filters to approve the mathematical formulation of the TDM model. At last, the output resolutions of TDM and classical HFB-based ADC are compared considering practical analog filters including realization errors. It is shown that the TDM architecture is less sensitive to the realization errors than the classical HFB. Besides, the TDM HFB can exploit a blind technique to correct the realization errors in opposite to the classical HFB case.
Circuits and Systems, 2007. MWSCAS 2007. 50th Midwest Symposium on; 09/2007
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ABSTRACT: Subband Hybrid Filter Bank (HFB) structures may replace the classic ones in parallel A/D Converters (ADC). In this paper, subband and original HFB-based A/D converters are simulated and compared in the time domain. For this purpose, firstly a brief survey on subband HFB-based A/D converters is presented. According to the simulations, subband HFB-based ADC exhibits a lower sensitivity to realization errors than classic one. Besides, compensation techniques such as noise canceling may be used for correcting the analog imperfections of subband HFB. This is not possible for classic HFB. The output resolution of subband HFB-based ADC is shown to be better than the one related to classic architecture using FIR synthesis filters with the same order for some exemplary inputs. Computation complexity related to subband architecture is compared with the one due to classic structure. It may be seen that subband HFB-based ADC includes less computational complexity than the classic architecture if an adaptive compensation of analog imperfections is considered.
Signal Processing and Its Applications, 2007. ISSPA 2007. 9th International Symposium on; 03/2007
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ABSTRACT: Hybrid filter banks (HFB) are considered as good candidate for implementing wide-band, high-frequency A/D parallel converters. The performance of HFB (original and two- stage) structures is analyzed for different values of oversampling ratios leading to the choice of the optimal value. The electronic elements of the analysis filter bank of HFB structure are considered with real constraints (realization errors and drifts). Real analysis filters of HFB are considered with the analog elements for which the real values are randomly Gaussian-distributed. Sensitivity to the deviations from real values is simulated and the performance of two HFB (original and two-stage) structures are compared. The possible methods for decreasing the sensitivity to realization errors such as Total Least Squares (TLS) optimization are discussed. Original structure is found to be a better candidate rather than the two-stage one in practical cases. However, it is shown that a blind estimation method would be necessary to compensate the realization errors for practically implementing the HFB-based A/D converters.
Circuits and Systems, 2006. MWSCAS '06. 49th IEEE International Midwest Symposium on; 09/2006
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ABSTRACT: Hybrid filter banks (HFB) are the suitable candidates for implementing wide-band, high-frequency A/D parallel converters. This paper proposes a modified HFB configuration called two-stage structure to overcome the aliasing constraints. This structure yields much better performance in terms of aliasing, or equally a higher possible resolution than the original one. Moreover, this two-stage structure can provide the performance of the original one with approximately only half the number of coefficients in the FIR synthesis filters. Results will be shown in the realistic case when the analog analysis filters are easy-to-implement RLC (or RC) circuits.
Signal Processing Systems Design and Implementation, 2005. IEEE Workshop on; 12/2005
