| 1. |
- Deng, Mingxin, et al.
(författare)
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Efficient Parallel Polynomial-Based Compensation Structure for Frequency Response Mismatch in Two-Channel TI-ADCs
- 2024
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Ingår i: IEEE Transactions on Circuits and Systems - II - Express Briefs. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1549-7747 .- 1558-3791. ; 71:2, s. 992-996
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Tidskriftsartikel (refereegranskat)abstract
- This brief introduces a compensation structure for frequency response mismatch (FRM) errors in two-channel time-interleaved analog-to-digital converters (TI-ADCs) based on polynomial models of the channel frequency responses. It can be used for any Nyquist band and it comprises parallel error approximation branches (EABs), each branch consisting of a fixed differentiator of unique degree cascaded with a variable multiplier and a simple modulator. It suffices to alter the variable multipliers when the channels change, thereby avoiding online filter design. In addition, it achieves a lower latency and a significantly lower computational complexity compared to cascaded polynomial-based structures. Numerical simulations and comparisons are included, validating the efficacy of the proposed structure.
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| 2. |
- Liu, Xiangyu, et al.
(författare)
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Correlation-Based Calibration for Nonlinearity Mismatches in Dual-Channel TIADCs
- 2020
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Ingår i: IEEE Transactions on Circuits and Systems - II - Express Briefs. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1549-7747 .- 1558-3791. ; 67:3, s. 585-589
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Tidskriftsartikel (refereegranskat)abstract
- Mismatches affect the dynamic performance of time-interleaved analog-to-digital converters (TIADCs). Linear mismatches can be calibrated by many mature methods, but if higher performance is required, nonlinearity mismatches have to be suppressed. The background calibration method based on input-free band (IFB) functions poorly for narrow-band signals. This brief proposes a correlation-based calibration method for nonlinearity mismatches in dual-channel TIADCs which behaves well for both wide-band and narrow-band signals. The output samples are calibrated by reducing the residual distortions which are approximated by multiplying the pseudo distortions and the estimated mismatch coefficients. The pseudo distortions are acquired by using a frequency-shifter, a differentiator, and multipliers. The coefficients which indicate the mismatch strength are estimated by eliminating the cross-correlation of the calibrated output samples and the calibrated pseudo distortions at zero lag. Simulations show that the proposed method can improve the SFDR by dozens of dBc for narrow-band input signals, compared with the IFB method. For the 16-QAM signal, the error vector magnitude improvement over the IFB method is 35.48 dB.
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| 3. |
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| 4. |
- Wang, Yinan, et al.
(författare)
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Adaptive Background Estimation for Static Nonlinearity Mismatches in Two-Channel TIADCs
- 2015
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Ingår i: IEEE Transactions on Circuits and Systems - II - Express Briefs. - : Institute of Electrical and Electronics Engineers (IEEE). - 1549-7747 .- 1558-3791. ; 62:3, s. 226-230
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Tidskriftsartikel (refereegranskat)abstract
- Due to channel mismatches in time-interleaved analog-to-digital converters (TIADCs), estimation and compensation methods are required to restore the resolution of the individual converters. Whereas several methods exist for linear mismatches, nonlinearity mismatches have not been widely investigated. This brief presents an adaptive background estimation method for nonlinearity mismatches in two-channel TIADCs. It utilizes a normalized least-mean-square algorithm and assumes slight oversampling as well as a polynomial nonlinearity model that is appropriate when smooth errors dominate. Furthermore, two implementation strategies are proposed to enhance its ability for different applications. The estimation performance of the proposed method is evaluated through behavioral-level simulations.
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| 5. |
- Wang, Yinan, et al.
(författare)
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Bandwidth-efficient calibration method for nonlinear errors in M-channel time-interleaved ADCs
- 2016
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Ingår i: Analog Integrated Circuits and Signal Processing. - : SPRINGER. - 0925-1030 .- 1573-1979. ; 86:2, s. 275-288
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Tidskriftsartikel (refereegranskat)abstract
- In order to enhance the effective resolution of time-interleaved analog-to-digital converters (TI-ADCs), both linear and nonlinear channel mismatches should be carefully calibrated. This paper concentrates on a bandwidth-efficient background calibration method for nonlinear errors in M-channel TI-ADCs. It utilizes the least-mean square algorithm as well as a certain degree of oversampling to achieve adaptive mismatch tracking. The calibration performance and computational complexity are investigated and evaluated through behavioral-level simulations. Furthermore, a calibration strategy for narrow-band input signals is proposed and verified as an improvement of the basic calibration structure for such signals.
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| 6. |
- Wang, Yinan, et al.
(författare)
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Digital estimation and compensation method for nonlinearity mismatches in time-interleaved analog-to-digital converters
- 2015
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Ingår i: Digital signal processing (Print). - : Elsevier. - 1051-2004 .- 1095-4333. ; 41, s. 130-141
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Tidskriftsartikel (refereegranskat)abstract
- Channel mismatches in time-interleaved analog-to-digital converters (TIADCs) typically result in significant degradation of the ADCs dynamic performance. Offset, gain, and timing mismatches have been widely investigated whereas nonlinearity mismatches have not. In this work, we analyze the influence of nonlinearity mismatches by using a polynomial model. As a cost measure we use the signal-to-noise and distortion ratio (SNDR) and then derive a compact formula describing the dependency on nonlinearity mismatches. Based on the spectral characteristics of the TIADCs, we propose a foreground estimation method and a compensation method using a cascaded structure of adders and multipliers. Through behavioral-level simulations, we prove the validity of the derivations and demonstrate that the proposed estimation and compensation method can bring a considerable amount of improvement in the combined TIADCs dynamic performance. The proposed method is efficient assuming that a smooth approximation of the nonlinearity mismatches is sufficient.
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| 7. |
- Wang, Yinan, et al.
(författare)
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Joint Blind Calibration for Mixed Mismatches in Two-Channel Time-Interleaved ADCs
- 2015
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Ingår i: IEEE Transactions on Circuits and Systems Part 1. - : Institute of Electrical and Electronics Engineers (IEEE). - 1549-8328 .- 1558-0806. ; 62:6, s. 1508-1517
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Tidskriftsartikel (refereegranskat)abstract
- To further enhance the dynamic performance of time-interleaved analog-to-digital converters (TI-ADCs), both linear and nonlinear mismatches should be estimated and compensated for. This paper introduces a method for joint calibration of several types of linear and nonlinear mismatch errors in two-channel TI-ADCs. To demonstrate the generality of this method, we take different scenarios into account, including static and dynamic mixed mismatch models. The proposed method utilizes a normalized least-mean square (N-LMS) algorithm as well as a certain low degree of oversampling for the overall converter to estimate and compensate for the mixed mismatch errors. The calibration performance and computational complexity are investigated and evaluated through simulations.
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| 8. |
- Wang, Yinan, et al.
(författare)
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Minimax design and order estimation of FIR filters for extending the bandwidth of ADCs
- 2016
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Ingår i: 2016 IEEE International Symposium on Circuits and Systems (ISCAS). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781479953417 - 9781479953400 - 9781479953424 ; , s. 2186-2189
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Konferensbidrag (refereegranskat)abstract
- The bandwidth of the sampling systems, especially for time-interleaved analog-to-digital converters, needs to be extended along with the rapid increase of the sampling rate. A digitally assisted technique becomes a feasible approach to extend the analog bandwidth, as it is impractical to implement the extension in analog circuits. This paper derives accurate order estimation formulas for the bandwidth extension filter, which is designed in the minimax sense with the ripple constraints as the design criteria. The derived filter order estimation is significant in evaluating the computational complexity from the viewpoint of the top-level system design. Moreover, with the proposed order estimates, one can conveniently obtain the minimal order that satisfies the given ripple constraints, which contributes to reducing the design time. Both the performance of the extension filter and its order estimation are illustrated and demonstrated through simulation examples.
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