FIR Filter Banks Research Articles

Design and Polyphase Implementation of Rotationally Invariant 2D FIR Filter Banks Based on Maximally Flat Prototype

Design and Polyphase Implementation of Rotationally Invariant 2D FIR Filter Banks Based on Maximally Flat Prototype

Design of efficient alterable bandwidth FIR filterbank for hearing aid system

The lifestyle of any person depends on his ability to hear his surrounding sounds or voices. This is because each of our sense organs works interrelated. Without an ability to proper hearing, he/she cannot respond to the other person leading to a very less or no communication to the society. Although he has a good talent and knowledge within, he cannot be able to communicate or express unless he has a good hearing ability. Also, he faces emotive problems caused by a reduction in self-confidence. So, a requirement of designing an efficient hearing aid is much necessary to resolve the hearing loss problem. In this paper, design of an efficient alterable ten band Finite Impulse Response filter bank for the hearing aid is achieved. Among the various windowing techniques available, Hamming window is preferred to design the FIR filter owing to its relatively sharp main lobe width and also the first few lobes have good attenuation. In this filterbank, variability in the subband bandwidths is achieved by simply altering each subband's bandwidth and center frequency. Unlike fixed filterbank, the proposed design provides the advantage of matching most of the audiograms of different hearing-impaired persons more accurately with simple procedure leading to low cost and low hardware complexity. Also using an FIR filter in the filterbank leads to highly stable design. Thus, a design of highly qualitative filterbank compared to fixed bandwidth designs with high audiogram matching and less matching error is implemented.

A Low-Complexity Multiplier-Less Filter Bank Based on Modified IFIR for the SDR Channelizer

Digital filter banks are extensively used in an SDR channelizer for channelization. The objective of this research work is to design a low computational complexity FIR filter bank for generating sharp transition width channels for SDR. The design of unified and variable bandwidth channels for SDR using the proposed structure is based on the modified IFIR filter structure and cosine modulation technique (CMT). The performance of the proposed structure is demonstrated with the help of an example. The results show that the multiplier complexity of the proposed structure is less than those of other state-of-the art methods. The optimization techniques are incorporated in this work to further reduce the complexity of the proposed structure. With the help of canonical signed digit (CSD), multi-objective artificial bee colony (MOABC) and shift inclusive differential coefficients (SIDC) – common sub-expression elimination (CSE) optimization, the filter used in this structure is made multiplier-less.

Design of special structure FIR filters and two-channel quadrature mirror FIR filter bank with sparse coefficients

The sparse design of special structure FIR filters (e.g., matrix-decomposition based FIR filter and frequency response mask based FIR filter) or special purpose FIR filters (e.g., the prototype FIR filter in the two-channel quadrature mirror FIR filter bank) is scarcely addressed previously. In this study, we deal with the sparse design of special structure/purpose FIR filters. A convergent scheme for the sparse design of special structure/purpose FIR filters is proposed. Its technical essence is a convergent scheme for minimizing the ℓk (k=1,2,…,∞) norm of the variable coefficients while the design error satisfying the desired requirement. The basic idea of the proposed scheme, for minimizing the ℓk norm of the variable coefficients, is approximately transforming all the sub-functions in the design error expression into linear ones using Taylor-Series. Thereby, the original non-convex design error turns to be convex. As part of the proposed scheme for the sparse design of special structure/purpose FIR filters, three new criteria of obtaining one more sparse coefficient are proposed. Simulation results validate the effectiveness of the proposed scheme in minimizing the ℓk norm of the variable coefficients and obtaining sparse coefficients in the sparse design of special structure/purpose FIR filters.

A power–performance partitioning approach for low‐power DA‐based FIR filter design with emphasis on datapath and controller

AbstractDistributed arithmetic (DA) is an efficient way to implement sum‐of‐product units, which can be used in applications such as FIR filters, filter banks, image processing, and convolutional neural networks in IoT hardware accelerators. In this paper, a low‐power architecture is offered centered on two key steps, coarse‐grain power‐performance partitioning and fine‐grain separated power supply, and tuned a level shifter in any digital systems implemented based on RTL design. To examine the new design approach, two methods are proposed, at first exploring the power consumption and critical delay path and then separating the power supply of datapath and controller in DA with/without utilizing an implicit level shifter. To investigate power consumption and timing parameters, two 5‐tap and 16‐tap FIR‐filters are implemented in 65‐nm CMOS standard technology. In proposed1, dynamic and static power consumption of 16‐tap (5‐tap) FIR‐filter is improved by 30% (15%) and 59% (59%), respectively. Nevertheless, the delay and slope of the generated signal in the shiftreg are significantly increased by reducing the power supply. To tackle this issue, the second method suggested with 26% (14%) improvement in dynamic power and 55% (58%) in static power consumption, which does not increase any delay in the output of shiftreg compared to conventional DA‐based FIR filter with solitary power supply.

Digital Hearing Aids Using Automated Varying Bandwidth Finite Impulse Response Filter Banks

A human auditory system is a highly complex sensitive system which transfers the acoustic sound into neuroelectrical signals toward the brain. Hearing difficulties or deafness are the outcomes of the problems occurred at any part of the auditory system. Assistive technologies such as hearing aids are developed to improve the quality of life of the hearing impaired people. Current digital hearing aids have fixed bandwidth filter banks which cannot provide enough flexibility to match with audiogram of different hearing loss. Recently, variable bandwidth filter banks have been introduced with different technologies to match more closely with the audiogram of a particular hearing loss. This research work proposes and implements a software controlled variable bandwidth FIR filter bank using Matlab GUI. In the Matlab GUI, in the filter bank, the bandwidth of every filter is adjusted dynamically in the Matlab GUI such that it fits more closely to the audiogram of a particular hearing loss. An experiment has been conducted in the developed Matlab GUI with various hearing loss, and the results show that the proposed system matches the filter bank magnitude response very closely to the audiogram of a particular hearing loss and reduces the matching error.

Optimal maximally decimated <i>M</i>-channel mirrored paraunitary linear phase FIR filter bank design via norm relaxed sequential quadratic programming

It is worth noting that the conventional maximally decimated M-channel mirrored paraunitary linear phase finite impulse response condition is defined in the frequency domain. As the frequency domain is a continuous set, it is expressed as a matrix functional (a continuous function of the frequency) equation. On the other hand, this paper expresses the condition as a finite number of discrete (a set of functions of the sampled frequencies) equations. Besides, this paper proposes to sample the magnitude responses of the filters with the total number of the sampled frequencies being more than the filter lengths. Hence, the frequency selectivities of the filters can be controlled more effectively. This filter bank design problem is formulated as an optimization problem in such a way that the total mirrored paraunitary linear phase error is minimized subject to the specifications on the magnitude responses of the filters at these sampling frequencies. However, this optimization problem is highly nonconvex. To address this difficulty, a norm relaxed sequential quadratic programming approach is applied for finding its local optimal solution. By iterating the above procedures using different initial conditions, a near global optimal solution is obtained. Computer numerical simulation results show that our proposed design outperforms the existing designs.

An Adaptive Blind Calibration Technique for Frequency Response Mismatches in M-Channel Time-Interleaved ADCs

This brief proposes a novel adaptive architecture for blind estimation and calibration of the frequency response mismatches in an M-channel time-interleaved analog-to-digital converter (TI-ADC). Based on the basis functions generated from the measured TI-ADC output, the mismatch errors could be reconstructed blindly and subtracted from the TI-ADC output adaptively. The advantage of the proposed technique is that it only needs to know the measured output signal without requiring any additional information and it is applicable to any channel TI-ADCs. Specially, the calibration structure only needs several differentiators with fixed coefficients without requiring a bank of adaptive FIR filters. In addition, the numerical simulations have been presented to demonstrate the effectiveness and superiority of the proposed technique, which shows that the proposed technique can improve the SNR and SFDR by over 25 dB.

Modeling and Simulation of Frequency Response Masking FIR Filter Bank using Approximate Multiplier for Hearing Aid Application

The tremendous increase in the use of portable electronic devices is due to the development in the fields of signal processing and electronic technology. These battery operated devices needs reduction in power consumption with increased performance and long battery life. Since CMOS technology scaling fast approaches its physical limit of minimum supply voltage and smaller feature size, the hardware designer has to opt for new multiplier architectures for achieving low power and high speed performance. This paper proposes an area and power efficient approximate multiplier architecture. The error metrics are estimated to verify its performance advantage over other approximate multipliers. Using Frequency Response masking approach, a 6-band non-uniform digital FIR filter bank is developed using approximate multiplier for hearing aid application. Audiogram matching is done with audiograms of two different types of hearing losses and the matching error is computed. Simulation results show that the audiogram matching error falls within +/- 4 dB range.

All-Digital Blind Background Calibration Technique for Any Channel Time-Interleaved ADC

This paper proposes a novel digital adaptive blind background calibration technique for the gain, timing skew, and offset mismatch errors in a time-interleaved analog-to-digital converter (TI-ADC). Based on the frequency-shifted basis functions generated only from the measured TI-ADC output, the three mismatch errors can be represented, extracted, and then subtracted from the TI-ADC output adaptively, which is quite different from the conventional methods (e.g., using a bank of adaptive FIR filters). The advantage of the proposed technique is that it only needs to know the measured output signal and the TI-ADC channel number, without needing any additional information; and it is applicable to any TI-ADCs with no limitations to the channel number, sub-ADC sampling rate, signal type, and so on. Specifically, the frequency-shifted signal generator employs the Hilbert transform and does not need extra finite impulse response filters. Extensive simulation and measurement results have been presented to demonstrate the effectiveness and superiority of the proposed technique, for single-tone, multi-tone, wideband modulated, and multi-band modulated signals. In the measurement for a 32GS/s 16-channel TI-ADC system, it shows that the proposed technique can improve the effective number of bit by 2 ~ 3 bit and the SFDR by 30 ~ 35 dB.

A Novel Design of Sparse Prototype Filter for Nearly Perfect Reconstruction Cosine-Modulated Filter Banks

Cosine-modulated filter banks play a major role in digital signal processing. Sparse FIR filter banks have lower implementation complexity than full filter banks, while keeping a good performance level. This paper presents a fast design paradigm for sparse nearly perfect-reconstruction (NPR) cosine-modulated filter banks. First, an approximation function is introduced to reduce the non-convex quadratically constrained optimization problem to a linearly constrained optimization problem. Then, the desired sparse linear phase FIR prototype filter is derived through the orthogonal matching pursuit (OMP) performed under the weighted l 2 norm. The simulation results demonstrate that the proposed scheme is an effective paradigm to design sparse NPR cosine-modulated filter banks.

Towards memristor-based approximate accelerator: application to complex-valued FIR filter bank

This paper presents a mixed-signal implementation of complex-valued FIR filter bank using a memristor-based approximate multiplier. First, a memristor-based vector–matrix multiplier was developed for complex number multiplications and then it was extended to perform the convolution operation. Finally, it was utilized for filtering application to study the potential capability of the memristor-based multipliers for accelerating digital signal processing. To evaluate the design, datasets presented by TDFIR kernel of HPEC benchmark suite, which include complex computations, were used. For simulations, Ngspice mixed-signal circuit simulator has been employed as a shared library in C++ programming environment. According to simulation results, using 6-bit accuracy for a 64 × 64 filter bank, the performance can be increased up to ~ 3 GFLOPS while presenting efficiency of ~ 4 GFLOPS/W. The results show that memristor-based mixed-signal architectures can be considered as favorable candidates for accelerating digital signal processing.

Efficient uniform digital filter bank with linear phase and FRM technique for hearing aids

This paper attempts to present an uniform digital filter bank based on linear phase FIR and IIR filters applied for Frequency Response Masking (FRM) technique in hearing aid applications.In the proposed filter bank, nine uniformly spaced sub-bands are formed with the help of half band filters and masking filters. These nine channel FIR filter bank is realized using an interpolated half band linear phase FIR filter and an appropriate number of masking FIR filters. The nine channel IIR filter bank is realized using an interpolated half band approximately linear phase IIR filter and an appropriate number of masking filters. The proposed approximately linear phase IIR half band filter bank is compared with filter bank based on linear phase FIR half band filters in terms of area, power, memory and number of gates needed for implementation. The experiment was carried on various hearing loss cases and the results obtained from these tests proves that, the proposed filter bank achieved the required matching between audiograms and magnitude response of the filter bank at very reasonable range with less computational complexity.

The Design of Digital Frequency-Shift Signal Detection Method Based on FPGA

In this paper, the design process of a portable railway frequency shift signal detection system is introduced in detail. With the parallelism of FPGA, the multitask can be carried out simultaneously. Two channels are designed to detect the two signals simultaneously. With the help of gear switching circuit, the measurement range and measurement accuracy of the system are greatly improved. Secondly, the FIR filter bank is designed based on FPGA, the signal is filtered and analyzed, the amplitude and frequency of the signal are detected, and the detection result is displayed in real time by using LCD.

Broken rotor bar detection via four-band wavelet packet decomposition of motor current

The induction motor current is nonstationary by nature, and time-scale analysis techniques such as wavelet packet decomposition (WPD) are more suitable for the analysis of the stator current for broken rotor bar detection. But, WPD is very costly in terms of the computational effort when half-band FIR filter banks are used in analysis. The implementation of four-band FIR filter banks in the analysis of a phase current is proposed here to reduce the computational cost. The use of four-band FIR filter banks with FPGA implementation would also provide higher levels of parallel processing capability resulting in further reduction in computational time required for detection of broken rotor bar faults. In WPD, it is also possible to tailor the frequency band size (resolution) so that one frequency band covers all motor fault induced frequencies due to rotor speed variations. Here, the rms value for broken rotor bar fault-related frequency band is compared with the baseline data to detect any broken rotor bar faults.

Biorthogonal Halfband Perfect Reconstruction Filterbank for Multimodal Image Fusion

Objectives: To design a wavelet filter bank which helps to detect more prominently continuous changes in tumor cells. Methods/Statistical Analysis: In this paper, a method of designing two-channel wavelet base FIR filter bank using factorization of a half band filter is presented. Here factorization is done considering maximum vanishing moments for construction of decomposition as well as reconstruction filters. The 14th order maximally flat halfband filter is proposed with factorization, leading to design of 8/8 orthogonal and 9/7 & 6/10 symmetric filters. Findings: The fusion performance of designed wavelet filter bank is evaluated using various performance metrics, like, cross entropy, standard deviation, mean square error and PSNR. The results are compared with the Daubechies filter bank where db4 is used for implementation. It is clear from the results that designed filter bank improves fusion performance. Further, proposed filters have maximum number of vanishing moments which gives smooth scaling and wavelet functions and consequently provides flat frequency response. Application/Improvements: The designed 8/8 orthogonal wavelet filters are implemented in fusion application for multimodal biomedical images of a subject for detection of an abnormality (cancerous growth). The novelty of this method is the adaptive design of the filterbank for the given multimodal images, so that fused images shall have more clarity, further, it will help to improve the results with enhancement in the entropy levels of fused image. Keywords: Filter Banks, Half Band Filter, Medical Image Processing, Multimodal Image Fusion, Spectral Factorization, Wavelet Transforms

On multiple‐resonator‐based implementation of TFT for harmonic analysis

The Taylor–Fourier transform (TFT) is suitable to analyse the spectrum of signals with non-stationary harmonics. It can be considered as an FIR filter bank consisting of maximally flat (MF) high-order filters which are computationally extensive and difficult for implementation. An adapted method is proposed for the TFT harmonic analysis which is based on the previously proposed multiple-resonator observer structure. The MF conditions are imposed to reshape frequency responses. This method by using a parallel structure with common feedback is very robust and, in addition, allows a reduction of the computational burden. Besides, this estimation method is adaptive and convenient for application in case of large frequency excursions, since the closed-form solutions allow that the fundamental frequency fluctuations can be followed by the filter central passband frequency.

Motor current signature analysis via four-channel FIR filter banks

Motor current signature analysis (MCSA) is capable of providing continuous monitoring of induction motors in a non-intrusive manner. Fourier based techniques have been used widely in processing of stator current but these techniques have a shortcoming in processing non-stationary signals such as the stator current. Recently, wavelet packet decomposition (WPD) has become popular in such applications since it gives better results in the case of non-stationary signals. The latter approach has much higher computational complexity limiting its use in motor diagnostics applications. In this study, the use of four-channel FIR filter banks is proposed to provide lower computational complexity. Four-channel filter banks employ higher level of parallel processing than currently used two-channel filter banks. FPGA implementation of the proposed algorithm would result in even further reduction in overall computation time.

Design of new class of regular biorthogonal wavelet filter banks using generalized and hybrid lifting structures

This paper proposed modified generalized lifting structure and hybrid lifting scheme in order to construct two-channel one-dimensional wavelet filter banks. The first structure is designed using general halfband polynomial by imposing any number of vanishing moments. The generalized even-step and odd-step lifting structure is derived separately to obtain FIR filter banks. The second approach is based on the combination of individual even-step and odd-step lifting structure called as hybrid lifting structure to improve the frequency response of filters. In this paper, the examples based on two-step, three-step, four-step, five-step and six-step lifting schemes are analyzed to investigate the properties of the wavelet filter banks. It is observed that the hybrid lifting scheme achieves more symmetry, more regularity, lower frame bounds ratio, good time–frequency localization and better frequency selectivity than individual two-step, three-step and five-step lifting schemes.

A state-space description for perfect-reconstruction wavelet FIR filter banks with special orthonormal basis functions

This paper presents a state space description for wavelet FIR filter banks with perfect reconstruction using special orthonormal basis functions. The FIR structure guarantees the BIBO stability, robustness and improves the filter divergence problem while orthonormal basis functions have characteristics that make them attractive in the modeling of dynamic systems. The state space description presented in this paper has all of those advantages and is minimal.