| 1. |
- Abbas, Muhammad, et al.
(författare)
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Comparison of Multiplierless Implementation of Nonlinear-Phase Versus Linear-Phase FIR filters
- 2008
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Konferensbidrag (refereegranskat)abstract
- FIR filters are often used because of their linear-phase response. However, there are certain applications where the linear-phase property is not required, such as signal energy estimation, but IIR filters can not be used due to the limitation of sample rate imposed by the recursive algorithm. In this work, we discuss multiplierless implementation of minimum order, and therefore nonlinear-phase, FIR filters and compare it to the linear-phase counterpart.
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| 2. |
- Sheikh, Zaka Ullah, et al.
(författare)
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A Technique for Efficient Realization of Wide-Band FIR LTI Systems
- 2012
-
Ingår i: IEEE Transactions on Signal Processing. - : IEEE Press. - 1053-587X .- 1941-0476. ; 60:3, s. 1482-1486
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Tidskriftsartikel (refereegranskat)abstract
- This correspondence introduces a technique for efficient realization of wide-band finite-length impulse response (FIR) linear and timeinvariant (LTI) systems. It divides the overall frequency region into three subregions through lowpass, bandpass, and highpass filters realized in terms of only one filter. The actual function to be approximated is in the low- and high-frequency regions realized using periodic subsystems. In this way, one can realize an overall wide-band LTI function in terms of three low-cost subblocks, leading to a reduced overall arithmetic complexity as compared to the regular realization. A systematic design technique is provided and a detailed example shows multiplication and addition savings of 62 and 48 percent, respectively, for a fractional-order differentiator with a 96 percent utilization of the bandwidth. Another example shows that the savings increase/decrease with increased/decreased bandwidth.
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| 3. |
- Sheikh, Zaka Ullah, et al.
(författare)
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Design of Narrow-Band and Wide-Band Frequency-Response Masking Filters Using Sparse Non-Periodic Sub-Filters
- 2010
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Konferensbidrag (refereegranskat)abstract
- In this work a new technique for design of narrow-band and wide-band linear-phase finite-length impulse response (FIR) frequency-response masking based filters is introduced. The technique is based on a sparse FIR filter design method for both the model (bandedge shaping) filter as well as the masking filter using mixed integer linear programming optimization. The proposed technique shows promising results for realization of efficient low arithmetic complexity structures.
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| 4. |
- Sheikh, Zaka Ullah, et al.
(författare)
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Design of sparse non-periodic narrow-band and wide-band FRM-like FIR filters
- 2010
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Ingår i: Proceedings of the International Conference on Green Circuits and Systems (ICGCS), 2010. - 9781424468775 - 9781424468768 ; , s. 279-282
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Konferensbidrag (refereegranskat)abstract
- In this work, a design method for narrow-band and wide-band frequency-response masking FIR filters is proposed. As opposed to most previous works, the design method is not based on a periodic model filter. Instead, the masking filter is designed for a given stopband edge. The model filter design is based on optimizing the sparseness of the filter, and, hence, the resulting model filter is not required to be periodic.
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| 5. |
- Sheikh, Zaka Ullah, 1967-
(författare)
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Efficient Realizations of Wide-Band and Reconfigurable FIR Systems
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Complexity reduction is one of the major issues in today’s digital system designfor many obvious reasons, e.g., reduction in area, reduced power consumption,and high throughput. Similarly, dynamically adaptable digital systems requireflexibility considerations in the design which imply reconfigurable systems, wherethe system is designed in such a way that it needs no hardware modificationsfor changing various system parameters. The thesis focuses on these aspects ofdesign and can be divided into four parts.The first part deals with complexity reduction for non-frequency selectivesystems, like differentiators and integrators. As the design of digital processingsystems have their own challenges when various systems are translated from theanalog to the digital domain. One such problem is that of high computationalcomplexity when the digital systems are intended to be designed for nearly fullcoverage of the Nyquist band, and thus having one or several narrow don’t-carebands. Such systems can be divided in three categories namely left-band systems,right-band systems and mid-band systems. In this thesis, both single-rate andmulti-rate approaches together with frequency-response masking techniques areused to handle the problem of complexity reduction in non-frequency selectivefilters. Existing frequency response masking techniques are limited in a sensethat they target only frequency selective filters, and therefore are not applicabledirectly for non-frequency selective filters. However, the proposed approachesmake the use of frequency response masking technique feasible for the non-frequency filters as well.The second part of the thesis addresses another issue of digital system designfrom the reconfigurability perspective, where provision of flexibility in the designof digital systems at the algorithmic level is more beneficial than at any otherlevel of abstraction. A linear programming (minimax) based technique forthe coefficient decimation FIR (finite-length impulse response) filter design isproposed in this part of thesis. The coefficient decimation design method findsuse in communication system designs in the context of dynamic spectrum accessand in channel adaptation for software defined radio, where requirements can bemore appropriately fulfilled by a reconfigurable channelizer filter. The proposedtechnique provides more design margin compared to the existing method whichcan in turn can be traded off for complexity reduction, optimal use of guardbands, more attenuation, etc.The third part of thesis is related to complexity reduction in frequencyselective filters. In context of frequency selective filters, conventional narrow-band and wide-band frequency response masking filters are focused, where variousoptimization based techniques are proposed for designs having a small number ofnon-zero filter coefficients. The use of mixed integer linear programming (MILP)shows interesting results for low-complexity solutions in terms of sparse andnon-periodic subfilters.Finally, the fourth part of the thesis deals with order estimation of digitaldifferentiators. Integral degree and fractional degree digital differentiators areused in this thesis work as representative systems for the non-frequency selectivefilters. The thesis contains a minimax criteria based curve-fitting approach fororder estimation of linear-phase FIR digital differentiators of integral degree upto four.
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| 6. |
- Sheikh, Zaka Ullah, et al.
(författare)
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Efficient Wide-Band FIR LTI Systems Derived Via Multi-Rate Techniques and Sparse Bandpass
- 2012
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Ingår i: IEEE Transactions on Signal Processing. - : IEEE Signal Processing Society. - 1053-587X .- 1941-0476. ; 60:7, s. 3859-3863
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Tidskriftsartikel (refereegranskat)abstract
- This correspondence introduces efficient realizations of wide-band LTI systems. They are single-rate realizations but derived via multirate techniques and sparse bandpass filters. The realizations target mid-band systems with narrow don’t-care bands near the zero and Nyquist frequencies. Design examples for fractional-order differentiators demonstrate substantial complexity savings as compared to the conventional minimax-optimal direct-form realizations.
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| 7. |
- Sheikh, Zaka Ullah, et al.
(författare)
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Linear-Phase FIR Digital Differentiator Order Estimation
- 2011
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Ingår i: Proceedings of The 20th European Conference on Circuit Theory and Design, ECCTD2011. - 9781457706165 - 9781457706172 ; , s. 310-313
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Konferensbidrag (refereegranskat)abstract
- Commonly used design procedures for design of digital differentiators are based on various optimization techniques and are also iterative in nature. The order estimation, for differentiators is important from design point of view as it can help in reducing the design time by providing a good initial guess of the order to the iterative design procedures. Moreover, order estimation helps in giving a fairly good estimation of the computational complexity in the overall design. This paper presents the linear-phase, finite-length impulse response (FIR) filter order estimation for integral degree differentiators of up to fourth degree. The minimax optimization based technique for the filter design and the curve fitting is used.
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| 8. |
- Sheikh, Zaka Ullah, et al.
(författare)
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Linear Programming Design of Coefficient Decimation FIR Filters
- 2012
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Ingår i: IEEE Transactions on Circuits and Systems - II - Express Briefs. - 1549-7747 .- 1558-3791. ; 59:1, s. 60-64
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Tidskriftsartikel (refereegranskat)abstract
- The coefficient decimation technique for reconfigurable FIR filters was recently proposed as a filter structure with low computational complexity. In this brief, we propose to design these filters using linear programming taking all configuration modes into account, instead of only considering the initial reconfiguration mode as in previous works. Minimax solutions with significantly lower approximation errors compared to the straightforward design method in earlier works are obtained. In addition, some new insights that are useful when designing coefficient decimation filters are provided.
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| 9. |
- Sheikh, Zaka Ullah, et al.
(författare)
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Wideband Linear-Phase FIR Differentiators Utilizing Multirate and Frequency-Response Masking Techniques
- 2009
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Ingår i: Proceedings of IEEE International Symposium on Circuits and Systems, Taipei, Taiwan, May 24–27, 2009.. - : IEEE. ; , s. 293-296
-
Konferensbidrag (refereegranskat)abstract
- This paper introduces a structure for the realization of wide-hand linear-phase finite-length impulse response (FIR) differentiators. It is based on multirate and frequency-response masking techniques. Examples show that this structure achieves computational savings between some 10% and 65% for bandwidths in the range between 0.9 pi and 0.98 pi in comparison with conventional linear-phase differentiators.
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| 10. |
- Ullah Sheikh, Zaka, et al.
(författare)
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A Class of Wide-Band Linear-Phase FIR Differentiators Using a Two-Rate Approach and the Frequency-Response Masking Technique
- 2011
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Ingår i: IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS. - : IEEE Press. - 1549-8328. ; 58:8, s. 1827-1839
-
Tidskriftsartikel (refereegranskat)abstract
- This paper introduces a class of wide-band linear-phase finite-length impulse response (FIR) differentiators. It is based on two-rate and frequency-response masking techniques. It is shown how to use these techniques to obtain all four types of linear-phase FIR differentiators. Design examples demonstrate that differentiators in this class can achieve substantial savings in arithmetic complexity in comparison with conventional direct-form linear-phase FIR differentiators. The savings achievable depend on the bandwidth and increase with increasing bandwidth beyond the break-even points which are in the neighborhood of 90% (80%) of the whole bandwidth for Type II and III (Type I and IV) differentiators. The price to pay for the savings is a moderate increase in the delay and number of delay elements. Further, in terms of structural arithmetic operations, the proposed filters are comparable to filters based on piecewise-polynomial impulse responses. The advantage of the proposed filters is that they can be implemented using non-recursive structures as opposed to the polynomial-based filters which are implemented with recursive structures.
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