A Hybrid Differential Evolution Method for the Design of IIR Digital Filter

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Full Paper ACEEE Int. J. on Signal & Image Processing, Vol. 4, No. 1, Jan 2013

A Hybrid Differential Evolution Method for the Design of IIR Digital Filter Balraj Singh1, J.S. Dhillon2, Y.S. Brar3 1

Department of Electronics & Communication Engineering, Punjab Technical University, Giani Zail Singh Campus, Bathinda-151001, Punjab, India email: erbalrajsidhu@rediffmail.com 2 Department of Electrical & Instrumentation Engineering, Sant Longowal Institute of Engineering & Technology, Longowal-148106, Sangrur, Punjab, India email: jsdhillonp@yahoo.com 3 Department of Electrical Engineering, Guru Nanak Dev Engineering College, Ludhiana-141006, Punjab, India email: braryadwinder@yahoo.co.in

Abstract— This paper establishes methodology for the robust and stable design of infinite impulse response (IIR) digital filters using hybrid differential evolution method. Differential Evolution (DE) is undertaken as a global search technique and exploratory search is exploited as a local search technique. DE is a population based stochastic real parameter optimization technique relating to evolutionary computation, whose simple yet powerful and straight forward features make it very attractive for numerical optimization. Exploratory search aims to fine tune the solution locally in promising search area. This proposed DE method augments the capability to explore and exploit the search space locally as well globally to achieve the optimal filter design parameters by applying the opposition learning strategy and random migration. A multivariable optimization is employed as the design criterion to obtain the optimal stable IIR filter that minimizes the magnitude approximation error and ripple magnitude. DE method is implemented to design low-pass, high-pass, bandpass, and band-stop digital IIR filters. The achieved design of IIR digital filters by applying DE method authenticates that its results are comparable to other algorithms and can be effectively applied for higher filter design.

sis, secure communication, radar processing and biomedical etc are some of the areas where digital filters are useful. The design of digital IIR filters is achieved by either transformation or optimization technique. In the transformation technique, analog IIR filter is designed and then it is converted to digital IIR filter. By implementing transformation techniques [10], Butterworth, Chebyshev, and Elliptic functions, have been designed. Optimization methods have been applied whereby magnitude error, and ripple magnitudes of pass-band and stop-band are undertaken to measure performance of digital IIR filter design. Jiang et.al [30] has discussed the design of IIR digital filter by comprising stability constraint and has applied an iterative second-order cone programming method. Lightener et.al.[3] has discussed the simultaneous design in magnitude and group delay. A stability constraint with a prescribed pole radius has been derived from the argument principle of complex analysis for designing IIR digital filter. The semi-definite programming relaxation technique [31] has been implemented for design of IIR filter in a convex form. The design procedure is sequential and finds a feasible solution within a set of relaxed constraints. Normally conventional gradient-based design may easily get stuck in the local minima of error surface of IIR filters, due to its nonlinear and multimodal nature. To overcome the shortcomings of gradient methods, researchers have applied nature based optimization algorithms such as genetic algorithms [4,6,8,9,11,15,16], particle swarm optimization (PSO) [17], seeker- optimization- algorithm -based evolutionary method [20], simulated annealing (SA) [12], Tabu search [19], ant colony optimization [18], immune algorithm [22] etc for the design of digital filters. Natural selection and genetics have been the basis for evolutionary algorithms and these are used as promising optimization techniques. Genetic algorithm (GA) also falls in the category of evolutionary algorithms. GA is capable of searching multidimensional and multimodal decision spaces. These are also useful to optimize complex and discontinuous functions [8]. The digital IIR filter can be structured as cascade, parallel, or lattice. Tang et al.[8] have applied genetic algorithms for designing the digital IIR filters. Genetic algorithms sometimes encounter very slow convergence. For

Index Terms—Digital IIR filters, Differential Evolution, Exploratory search algorithm, Multi-parameter, optimization, Opposition based learning, Random migration.

I. INTRODUCTION The need for numerical optimization algorithms arises from almost every field of engineering, science, and business. This is because; an analytical optimal solution is difficult to obtain even for relatively simple application problems. A numerical algorithm is expected to perform the task of global optimization of a multimodal and non linear objective functions. However, an objective function possesses numerous local optima, which could trap the numerical algorithms. The possibility of failing to locate the desired global solution increases with the Increase in the problem dimension. The main challenge in designing infinite impulse response (IIR) digital filters is its nonlinearity and stability aspects in comparison to finite impulse response (FIR) digital filter design. The digital filters can be implemented through either hardware or software. These are capable of processing both realtime and on-line signals. Image processing, speech syntheŠ 2013 ACEEE DOI: 01.IJSIP.4.1.15

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