A New Time-Domain Approach for the Design of Variable FIR Filters Using the Spectral Parameter Approximation Technique

Dhabu, Sumedh; Vinod, A. P.

doi:10.1007/s00034-016-0407-3

Cited by 8 publications

(7 citation statements)

References 13 publications

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“…A method in [11,12] technique [38][39][40][41][42][43][44][45][46][47][48][49][50][51], main difference being the manner (on-line for [11,12] and offline for SPA) in which the approximation is carried out. Also, as opposed to the SPA technique, it lacks clear and strong background, and results in less accurate VCF filter responses.…”

Section: Variable-coefficient Vcf Filtersmentioning

confidence: 99%

“…In the SPA technique [38][39][40][41][42][43][44][45][46][47][48][49][50][51], the frequency response of the variable (fractional delay or the cutoff frequency)…”

Section: Spectral Parameter Approximation Based Vcf Filtersmentioning

confidence: 99%

“…The objective here is to find the optimal sub-filter coefficients such that the frequency response of the SPA based VCF filter approximates the desired VCF filter response as a function of α. Various design methods utilizing the least-squares [38][39][40][41][42][43]51] and/or minimax techniques [44][45][46][47][48],vector array decomposition [49], semi-infinite quadratic optimization [50] have been proposed in literature to solve the approximation problem by incorporating the desired peak to peak passband ripple and stopband attenuation constraints in the problem formulation. The optimal solutions can be obtained from the closed-form formulae [39][40][41][42][43]47], or by solving the system of linear equations obtained by the discretization method [38,[44][45][46][48][49][50][51].…”

Section: Spectral Parameter Approximation Based Vcf Filtersmentioning

confidence: 99%

“…Various design methods utilizing the least-squares [38][39][40][41][42][43]51] and/or minimax techniques [44][45][46][47][48],vector array decomposition [49], semi-infinite quadratic optimization [50] have been proposed in literature to solve the approximation problem by incorporating the desired peak to peak passband ripple and stopband attenuation constraints in the problem formulation. The optimal solutions can be obtained from the closed-form formulae [39][40][41][42][43]47], or by solving the system of linear equations obtained by the discretization method [38,[44][45][46][48][49][50][51]. In general, all the sub-filters in the Farrow structure have the same order, but unequal order case has also been treated in [44].…”

Section: Spectral Parameter Approximation Based Vcf Filtersmentioning

confidence: 99%

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Variable cutoff frequency FIR filters: a survey

et al. 2020

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Many signal processing applications require digital filters with variable frequency characteristics, especially the filters with variable bandwidth. Due to their linear phase and inherent stability, variable bandwidth finite impulse response (FIR) filters are the popular choice in majority of the applications. Once a variable cutoff frequency (VCF) FIR lowpass filter is designed, variable bandwidth bandpass / highpass / bandstop filters and reconfigurable filter banks can be realized from the same. In this paper, we present a comprehensive review of the existing variable cutoff frequency FIR filter design techniques, including the developments in the recent two decades. We provide the basic concepts, design and architectural details for each of these techniques and the major developments / incremental works thereof. Qualitative as well as quantitative comparisons are provided to assist the reader in choosing the most suitable VCF filter design technique for a particular application. Keywords FIR filters, reconfigurable filters, variable digital filters IntroductionCompared to analog filters, digital filters have advantage of higher accuracy, exact linear-phase (if desired), time-invariant performance (analog filter performance changes due to component drift), relatively smaller silicon area etc. These advantages, coupled with the advent of VLSI technology, have resulted in ubiquitous presence of digital filters in almost all the signal processing applications with a few exceptions (such as wideband filtering in radio frequency range, which is not feasible due to the bottleneck at the speed of analog-to-digital converters).Digital filters with variable frequency response characteristics are required for numerous critical applications in the fields of digital communications, audio signal processing, biomedical signal processing etc. [1,2]. In digital communications domain alone, digital filters with variable frequency response characteristics can be used for spectrum analysis, spectrum shaping, channelization, and receiver synchronization. For e.g., a digital filter having tuneable passband and transition bandwidths is used for channel extraction in a multi-standard wireless communication receiver, as it needs to be interoperable with multiple communication standards having distinct bandwidth specifications. Alternatively, a digital modem uses a digital filter to implement variable fractional delays. In general, a digital filter whose frequency response can be changed on-the-fly is called a variable digital filter. Even though such a definition means that all the parameters related to the frequency response should be variable, in practice, majority of the applications demand only a lowpass filter with variable cutoff frequency (fc), satisfying the desired minimum specifications of transition bandwidth (tbw), passband ripple (δp) and stopband ripple (δs). Therefore, the VCF (variable cutoff frequency) filter design task can be simplified further, by specifying the maximum limit on tbw, δp, and δs, and thus, only one...

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Section: Variable-coefficient Vcf Filtersmentioning

confidence: 99%

“…In the SPA technique [38][39][40][41][42][43][44][45][46][47][48][49][50][51], the frequency response of the variable (fractional delay or the cutoff frequency)…”

Section: Spectral Parameter Approximation Based Vcf Filtersmentioning

confidence: 99%

Section: Spectral Parameter Approximation Based Vcf Filtersmentioning

confidence: 99%

Section: Spectral Parameter Approximation Based Vcf Filtersmentioning

confidence: 99%

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Variable cutoff frequency FIR filters: a survey

et al. 2020

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“…To improve the cut-off frequency range, frequency transformation techniques can be combined with coefficient decimation techniques [19]. Variable bandwidth filters can be obtained through Spectral Parameter Approximation (SPA) techniques [20]. The SPA technique was initially used for designing variable fractional delay filters but later adapted to design variable bandwidth filters.…”

Section: Introductionmentioning

confidence: 99%

A low complexity and high modularity design for continuously variable bandwidth digital filters

Sajeevu¹,

Sakthivel²

2021

Preprint

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Digital filters with variable bandwidth can be used for a variety of applications. Arbitrary change in the bandwidth of a digital Finite Impulse Response (FIR) filter can be acquired using sampling rate converters. In this paper, a sampling rate converter is proposed which is generated from Pascal structure, a fractional delay filter having low hardware complexity and high modularity. The proposed sampling rate converter requires lesser number of multipliers for implementation when compared with the sampling rate converters in the literature. A low pass filter having a single bandwidth sandwiched between two sampling rate converters can contribute multiple bandwidths in such a way that each bandwidth is an arbitrary variation of the original bandwidth. A two stage Frequency response masking approach (FRM) is used for the hardware efficient design of the original low pass filter. A low complexity and high modular novel design for a continuously varying bandwidth of a digital FIR filter is proposed in this paper using the proposed sampling rate converter. The modularity of the Pascal structure can be used to control both pass band ripple as well as stop band attenuation of the continuously variable bandwidth FIR filter design. Different communication standards in a Software defined radio (SDR) channelizer is realized using the proposed design of continuously variable bandwidth filter.

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