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1.
A very efficient technique for drastically reducing the number of multipliers
and adders in narrow transition-band linear-phase finite impulse response (FIR) filters
is to use the one-stage or multistage frequency-response masking (FRM) approach as
originally introduced by Lim. In the original synthesis techniques developed by Lim and
Lian, the subfilters in the overall approach were designed using time-consuming linear
programming. In order to perform the overall synthesis faster, this paper shows how these
subfilters can be designed with the aid of the the Remez multiple exchange algorithm,
the most powerful technique for designing arbitrary-magnitude linear-phase FIR filters
in the minimax sense. In addition to speeding up the overall procedure, the use of the
Remez algorithm enables one to generate a very fast MATLAB program for the overall
synthesis so that after being given the filter specifications as well as the number of stages,
the program automatically provides the solution with the minimum number of multipliers
and adders required in the overall implementation. This is possible because the MATLAB
Remez routine is directly available and thus can be used for this purpose after appropriate
modifications. 相似文献
2.
A new method to reduce the number of arithmetic operations in a sharp FIR filter
synthesized by the frequency-response masking (FRM) technique is presented. The success
of the proposed method is based on a modified FRM approach where the subfilters in
the FRM approach are implemented by using recently introduced prefilter-equalizer based
filters. It is shown, by means of examples, that the proposed method yields considerable
savings in the numbers of multipliers and adders compared to the original single-stage
FRM approach. 相似文献
3.
In the frequency-response masking (FRM) approach, the complexity of two
masking filters is heavily dependent on the interpolation factor and the cutoff frequencies
of the bandedge shaping filter. In this paper, we propose a novel structure that decouples
the masking filters from the bandedge shaping filter. The design equations together with the
design procedures are presented. With the introduction of an additional decoupling stage,
the complexity of the overall filter can be greatly reduced. Our example shows that more
than 40% savings in the numbers of multipliers and adders can be achieved compared with
the original FRM approach. 相似文献
4.
The introduction of nonlinear optimization techniques to the design of a frequency-response masking (FRM) filter has changed
the way in which an FRM filter is synthesized. It allows all subfilters in an FRM structure to be optimized jointly, resulting
in further savings in the number of arithmetic operations. Under the joint optimization, a new set of design equations is
necessary, not only for a more computationally efficient filter, but also for the simplification of the design process and
the reduction of the design time. In this paper, we present a set of design equations that estimates the filter lengths and
optimum interpolation factor in an FRM filter under joint optimization. It is shown, by means of examples, that the proposed
design equations lead to a better estimation of the optimum interpolation factor compared with existing design equations. 相似文献
5.
This paper offers two main contributions to the theory of low-delay frequency-response masking (FRM) finite impulse response
(FIR) filters. First, a thorough investigation of the low-delay FRM FIR filters and their subfilters or three different structures,
referred to as narrow-, wide-, and middle-band filter structures, is given. The investigation includes discussions on delay
distribution over the subfilters as well as estimation of the optimal periodicity of the periodic model filter. Second, systematic
design procedures are given, with explicit formulas for distribution of the ripples and the delay to the subfilters. For each
of the three structures, two design procedures are given that include joint optimization of the subfilters. The first proposal
uses partly linear-phase FIR subfilters and partly low-delay FIR subfilters. Thus, it has a lower arithmetic complexity compared
to the second proposal, which has exclusively low-delay FIR subfilters. The second proposal is instead more flexible and can
handle a broader range of specifications. The design procedures result in low-delay FIR filters with a lower arithmetic complexity
compared to previous results, for specifications with low delay and narrow transition band. 相似文献
6.
A method for the design of linear-phase digital filters by the tapped cascaded interconnection of identical subfilters is presented. The method is an extension of the method proposed by Saramaki (1987). An example is given to show that the number of distinct multipliers of the filter determined by the proposed method is less than that of filters determined by Saramaki's method (1987). We also consider the case in which the subfilters are determined by multiple use of a single filter. In particular, if we can make the subfilters multiplierless then the number or multiplications per sample required to implement the overall filter is less than that required by the direct-form minimax method. Methods for the design of computationally efficient filters are also developed based on the proposed transformation method. The multiplication rate of the overall filter is the same as that of the prototype filter. It is very low as compared to that designed by the equivalent direct-form minimax method. With the proposed transformation method, methods for the design of a filter having nth-order tangency at both ends (0, π) are also developed. This is an extension of Vaidynathan's method (1985) and the proposed transformation method. The advantages of the method are that the resulting filters have very flat passbands and the stopbands are computationally efficient. 相似文献
7.
This paper considers the design of an FIR digital filter by interconnecting a number of identical FIR subfilters with the aid of a few additional multipliers and adders. The overall structure is in the form of a tapped cascaded FIR subfilters. A composite method to determine the tapping coefficients along with the coefficients of the subfilter to approximate overall frequency response characteristic is proposed. Several numerical examples illustrating the proposed method are included. 相似文献
8.
The most computationally intensive part of the wideband receiver of a software defined radio (SDR) is the intermediate frequency (IF) processing block. Digital filtering is the main task in IF processing. The computational complexity of finite impulse response (FIR) filters used in the IF processing block is dominated by the number of adders (subtracters) employed in the multipliers. This paper presents a method to implement FIR filters for SDR receivers using minimum number of adders. We use an arithmetic scheme, known as pseudo floating-point (PFP) representation to encode the filter coefficients. By employing a span reduction technique, we show that the filter coefficients can be coded using considerably fewer bits than conventional 24-bit and 16-bit fixed-point filters. Simulation results show that the magnitude responses of the filters coded in PFP meet the attenuation requirements of wireless communication standard specifications. The proposed method offers average reductions of 40% in the number of adders and 80% in the number of full adders needed for the coefficient multipliers over conventional FIR filter implementation methods 相似文献
9.
A method is presented to synthesize wideband linear-phase finite-impulse-response (FIR) filters with a piecewise-polynomial-sinusoidal
impulse response. The method is based on merging the earlier synthesis scheme proposed by the authors to design piecewise-polynomial
filters with the method proposed by Chu and Burrus. The method uses an arbitrary number of separately generated center coefficients
instead of only one or none as used in the method by Chu–Burrus. The desired impulse response is created by using a parallel
connection of several filter branches and by adding an arbitrary number of center coefficients to form it. This method is
especially effective for designing Hilbert transformers by using Type 4 linear-phase FIR filters, where only real-valued multipliers
are needed in the implementation. The arithmetic complexity is proportional to the number of branches, the common polynomial
order for each branch, and the number of separate center coefficients. For other linear-phase FIR filter types the arithmetic
complexity depends additionally on the number of complex multipliers. Examples are given to illustrate the benefits of this
method compared to the frequency-response masking (FRM) technique with regard to reducing the number of coefficients as well
as arithmetic complexity. 相似文献
10.
This paper presents the design of high-speed, arbitrary
bandwidth sharp finite impulse response filters with signed
powers-of-two coefficients based on a modified
frequency-response masking (FRM) structure. A novel hybrid
genetic algorithm (HGA) is proposed to jointly optimize all
subfilters in a discrete space. The proposed HGA introduces the
simulated annealing technique into the genetic algorithm (GA)
optimization process and effectively prevents the GA from
prematurely converging. It is shown, by means of examples, that
FRM filters designed by the HGA achieve a significant reduction
in the number of bits. 相似文献
11.
12.
An efficient coefficient quantization scheme is described for minimizing the cost of implementing fixed parallel linear-phase
finite impulse response (FIR) filters in the modified Farrow structure introduced by Vesma and Saramaki for generating FIR
filters with an adjustable fractional delay. The implementation costs under consideration are the minimum number of adders
and subtracters when implementing these parallel subfilters as a very large-scale integration (VLSI) circuit. Two implementation
costs are under consideration to meet the given criteria. In the first case, all the coefficient values are implemented independently
of each other as a few signed-powers-of-two terms, whereas in the second case, the common subexpressions within all the coefficient
values included in the overall implementation are properly shared in order to reduce the overall implementation cost even
further. The optimum finite-precision solution is found in four steps. First, the number of filters and their (common odd)
order are determined such that the given criteria are sufficiently exceeded in order to allow some coefficient quantization
errors. Second, those coefficient values of the subfilters having a negligible effect on the overall system performance are
fixed to be zero valued. In addition, the experimentally observed attractive connections between the coefficient values of
the subfilters, after setting some coefficient values equal to zero, are utilized to reduce both the implementation cost and
the parameters to be optimized even more. Third, constrained nonlinear optimization is applied to determine for the remaining
infinite-precision coefficients a parameter space that includes the feasible space where the given criteria are met. The fourth
step involves finding in this space the desired finite-precision coefficient values for minimizing the given implementation
costs to meet the stated overall criteria. Several examples are included illustrating the efficiency of the proposed synthesis
scheme. 相似文献
13.
Design of Computationally Efficient Sharp FIR Filter Utilizing Modified Multistage FRM Technique for Wireless Communications Systems
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Modern wireless communications gadgets demand multi-standard communications facilities with least overlap between different input radio channels. A sharp digital filter of extremely narrow transition-width with lower stop band ripples offers alias-free switching among the preferred frequency bands. A computationally competent low pass filter (LPF) structure based on the multistage frequency response masking (FRM) approach is proposed for the design of sharp finite impulse response (FIR) filters which are suitable for wireless communications applications. In comparison of basic FRM with other existing multistage FRM structures, the proposed structure has a narrow transition bandwidth and higher stop band attenuation with significant reduction in terms of the number of computational steps. A design example is incorporated to demonstrate the efficiency of the proposed approach. Simulation results establish the improvement of the proposed scheme over other recently published design strategies. 相似文献
14.
In this paper, computationally efficient filter structures based on the frequency-response masking (FRM) technique are proposed
for the synthesis of arbitrary bandwidth sharp finite impulse response (FIR) filters. A serial masking scheme is introduced
in the new structures to perform the masking task in two stages, which reduces the complexity of the masking filters. Compared
to the original FRM and interpolated FIR-FRM (IFIR-FRM) structures, the proposed structures achieve additional savings in
terms of numbers of arithmetic operations. 相似文献
15.
Analog-to-digital converters based on sigma-delta modulation have shown promising performance, with steadily increasing bandwidth.
However, associated with the increasing bandwidth is an increasing modulator sampling rate, which becomes costly to decimate
in the digital domain. Several architectures exist for the digital decimation filter, and among the more common and efficient
are polyphase decomposed finite-length impulse response (FIR) filter structures. In this paper, we consider such filters implemented
with partial product generation for the multiplications, and carry-save adders to merge the partial products. The focus is
on the efficient pipelined reduction of the partial products, which is done using a bit-level optimization algorithm for the
tree design. However, the method is not limited only to filter design, but may also be used in other applications where high-speed
reduction of partial products is required.
The presentation of the reduction method is carried out through a comparison between the main architectural choices for FIR
filters: the direct-form and transposed direct-form structures. For the direct-form structure, usage of symmetry adders for
linear-phase filters is investigated, and a new scheme utilizing partial symmetry adders is introduced. The optimization results
are complemented with energy dissipation and cell area estimations for a 90 nm CMOS process. 相似文献
16.
17.
Wei Rong Lee Caccetta L. Kok Lay Teo Rehbock V. 《Signal Processing, IEEE Transactions on》2006,54(9):3459-3467
This paper presents a unified approach to the optimal design of sharp linear-phase finite-impulse-response (FIR) digital filters synthesized using the multistage frequency-response masking (FRM) technique. In this approach, the design of a k-stage FRM filter is achieved in a recursive manner. The minimax design problem arising at each step of the synthesis process is converted into a corresponding weighted least-squares (WLS) problem. The WLS problem is highly nonlinear with respect to the coefficients of the filter. Consequently, it is decomposed into several linear least-squares (LS) problems, each of which can be solved analytically. It is then solved iteratively by using an alternating variable approach. Numerical design examples are included to demonstrate the effectiveness of the method. 相似文献
18.
The most advanced techniques in the design of multiplierless finite impulse response (FIR) filters explore common subexpression
sharing when the filter coefficients are optimized. Existing techniques, however, either suffer from a heavy computational
overhead, or have no guarantees on the minimal hardware cost in terms of the number of adders. A recent technique capable
of designing long filters optimizes filter coefficients in pre-specified subexpression spaces. The pre-specified subexpression
spaces determine if a filter with fewer adders may be achieved. Unfortunately, there is no known technique that can find subexpression
spaces that can guarantee the solution with the minimum number of adders in the implementation. In this paper, a tree search
algorithm is proposed to update and expand the subexpression spaces dynamically, and thus, to achieve the maximum subexpression
sharing during the optimization. Numerical examples show that the proposed algorithm generates filters using fewer adders
than other non-optimum algorithms. On the other hand, as a consequence of its efficiency, our proposed technique is able to
design longer filters than the global optimum algorithm. 相似文献
19.
Sai Mohan Kilambi Behrouz Nowrouzian Yifan Wu 《Circuits, Systems, and Signal Processing》2008,27(5):599-625
The conventional frequency response masking (FRM) approach is one of the most well-known techniques for the design of sharp
transition band finite impulse response (FIR) digital filters. The resulting FRM digital filters permit efficient hardware
implementations due to an inherently large number of zero-valued multiplier coefficients. The hardware complexity of these digital filters can further be reduced by representing the remaining
(non-zero) multiplier coefficient values by using their canonical signed-digit (CSD) representations. This paper presents
a novel diversity-controlled (DC) genetic algorithm (GA) for the discrete optimization of bandpass FRM FIR digital filters
over the CSD multiplier coefficient space. The resulting bandpass FIR digital filters are permitted to have equal or unequal
lower and upper transition bandwidths. The proposed DCGA is based on an indexed look-up table of permissible CSD multiplier
coefficients such that their indices form a closed set under the genetic operations of crossover and mutation. The salient
advantage of DCGA over the conventional GA lies in the external control over population diversity and parent selection, giving
rise to a rapid convergence to an optimal solution. The external control is achieved through the judicious choice of a pair
of DCGA optimization parameters. An empirical investigation is undertaken for choosing appropriate values for these control
parameters. The convergence speed advantages of the DCGA are demonstrated through its application to the design and optimization
of a pair of bandpass FRM FIR digital filters with equal or arbitrary lower and upper transition bandwidths. In both cases,
an increase of about an order of magnitude in the speed of convergence is achieved as compared to the conventional GAs. 相似文献
20.
A novel approach to the design of multiplierless filters, based on the ACF (amplitude change function), is discussed. The prototype filter chosen is a CCOS (the cascade of the cosine functions) which requires no multipliers and only some adders. The required filter specifications are met by multiple use of the same CCOS filter. Effects due to coefficient quantisation do not arise when using the new approach. No multipliers are required to implement this filter.<> 相似文献