This article presents a piecewise linear approximation computation (PLAC) method for all nonlinear unary functions, which is an enhanced universal and error-flattened piecewise linear (PWL) ...approximation approach. Compared with the previous methods, PLAC features two main parts, an optimized segmenter to seek the minimum number of segments under the predefined software maximum absolute error (MAE), raising the segmentation performance to the highest theoretical level for logarithm, and a novel quantizer to completely simulate the hardware behavior and determine the required bit width and <inline-formula> <tex-math notation="LaTeX">{\text {MAE}}_{c} </tex-math></inline-formula> (MAE in circuits) for hardware implementation. In addition, the hardware architecture is also improved by simplifying the indexing logic, leading to nonredundant hardware overhead. The ASIC implementation results reveal that the proposed PLAC can improve all metrics without any compromise. Compared with the state-of-the-art methods, when computing logarithmic function, PLAC reduces 2.80% area, 3.77% power consumption, and 1.83% <inline-formula> <tex-math notation="LaTeX">{\text {MAE}}_{c} </tex-math></inline-formula> with the same delay; when approximating hyperbolic tangent function, PLAC reduces 6.25% area, 4.31% power consumption, and 18.86% <inline-formula> <tex-math notation="LaTeX">{\text {MAE}}_{c} </tex-math></inline-formula> with the same delay; when evaluating sigmoid function, PLAC reduces 16.50% area, 4.78% power consumption with the same delay, and <inline-formula> <tex-math notation="LaTeX">{\text {MAE}}_{c} </tex-math></inline-formula>; and when calculating softsign function, PLAC reduces 17.28% area, 11.34% power consumption, 12.50% delay, and 33.28% <inline-formula> <tex-math notation="LaTeX">{\text {MAE}}_{c} </tex-math></inline-formula>.
This article presents hardware implementation for computing arbitrary roots of a single-precision floating-point number. The proposed architecture is based on Generalized Hyperbolic COordinate ...Rotation Digital Computer (GH CORDIC) algorithm. Benefiting from the wide range of floating-point numbers, our design is able to compute the Nth root (N ≥ 2) of a single-precision floating-point number. After implementation, a series of tests have been carried out, including accuracy, power consumption, performance comparison, and so on. Simulation results indicate that our proposed method is capable of calculating the Nth root of a positive single-precision floating-point number with a relative error of 10 -7 approximately and promises an error-flatten performance. Synthesized results from a design compiler under TSMC-40-nm CMOS technology show that our design can achieve the highest frequency of 2.38 GHz with the area consumption of 140894.44 μm 2 and power consumption of 86.9573 mW.
Aiming at the practical constraints of high resource occupancy and complex calculations in the existing Spike Neural Network (SNN) image classification model, in order to seek a more lightweight and ...efficient machine vision solution, this paper proposes an adaptive threshold Spike Neural Network (SNN) model of lateral inhibition of Spike-Timing-Dependent Plasticity (STDP). The conversion from grayscale image to pulse sequence is completed by convolution normalization and first pulse time coding. The network self-classification is realized by combining the classical Spike-Timing-Dependent Plasticity algorithm (STDP) and lateral suppression algorithm. The occurrence of overfitting is effectively suppressed by introducing an adaptive threshold. The experimental results on the MNIST data set show that compared with the traditional SNN classification model, the complexity of the weight update algorithm is reduced from O(n2) to O(1), and the accuracy rate can still remain stable at about 96%. The provided model is conducive to the migration of software algorithms to the bottom layer of the hardware platform, and can provide a reference for the realization of edge computing solutions for small intelligent hardware terminals with high efficiency and low power consumption.
This paper presents a COordinate Rotation Digital Computer (CORDIC)-based architecture for the computation of Nth root and proves its feasibility by hardware implementation. The proposed architecture ...performs the task of Nth root simply by shift-add operations and enables easy tradeoff between the speed (or precision) and the area. Technically, we divide the Nth root computation into three different subtasks, and map them onto three different classes of the CORDIC accordingly. To overcome the drawback of narrow convergence range of the CORDIC algorithm, we adopt several innovative methods to yield a much improved convergence range. Subsequently, in terms of convergence range and precision, a flexible architecture is developed. The architecture is validated using MATLAB with extensive vector matching. Finally, using a pipelined structure with fixed-point input data, we implement the example circuits of the proposed architecture with radicand ranging from zero to one million, and achieve an average mean of approximately 10 −7 for the relative error. The design is modeled using Verilog HDL and synthesized under the TSMC 40-nm CMOS technology. The report shows a maximum frequency of 2.083 GHz with <inline-formula> <tex-math notation="LaTeX">197421.00~{\mu }\text{m}^{2} </tex-math></inline-formula> area. The area decreases to <inline-formula> <tex-math notation="LaTeX">169689.98~{\mu }\text{m}^{2} </tex-math></inline-formula> when the frequency lowers to 1.00 GHz.
In this paper, a new single-device three-dimensional (3D) Hall sensor called a cross-shaped 3D Hall device is designed based on the five-contact vertical Hall device. Some of the device parameters ...are based on 0.18 μm BCDlite
technology provided by GLOBALFOUNDRIES. Two-dimensional (2D) and 3D finite element models implemented in COMSOL are applied to understand the device behavior under a constant magnetic field. Besides this, the influence of the sensing contacts, active region's depth, and P-type layers are taken into account by analyzing the distribution of the voltage along the top edge and the current density inside the devices. Due to the short-circuiting effect, the sensing contacts lead to degradation in sensitivities. The P-type layers and a deeper active region in turn are responsible for the improvement of sensitivities. To distinguish the P-type layer from the active region which plays the dominant role in reducing the short-circuiting effect, the current-related sensitivity of the top edge (
) is defined. It is found that the short-circuiting effect fades as the depth of the active region grows. Despite the P-type layers, the behavior changes a little. When the depth of the active region is 7 μm and the thickness of the P-type layers is 3 μm, the sensitivities in the
,
, and
directions can reach 91.70 V/AT, 92.36 V/AT, and 87.10 V/AT, respectively.
Vertical Hall sensors (VHSs), compatible with complementary metal oxide semiconductor (CMOS) technology, are used to detect magnetic fields in the plane of the sensor. In previous studies, their ...performance was limited by a large offset. This paper reports on a novel CMOS seven-contact VHS (7CVHS), which is formed by adding two additional contacts to a traditional five-contact VHS (5CVHS) to alleviate the offset. The offset voltage and offset magnetic field of the 7CVHS are reduced by 90.20% and 88.31% of those of the 5CVHS, respectively, with a 16.16% current-related sensitivity loss. Moreover, the size and positions of the contacts are optimized in standard GLOBALFOUNDRIES 0.18 μm BCDliteTM technology by scanning parameters using FEM simulations. The simulation data are analyzed in groups to study the influence of the size and contact positions on the current-related sensitivity, offset voltage, and offset magnetic field.
Introduction Mango is a vital horticultural fruit crop, and breeding is an essential strategy to enhance ongoing sustainability. Knowledge regarding population structure and genetic diversity in ...mango germplasm is essential for crop improvement. Methods A set of 284 mango accessions from different regions of the world were subjected to high-throughput sequencing and specific-locus amplified fragment (SLAF) library construction to generate genomic single-nucleotide polymorphism (SNP). Results After filtering, raw data containing 539.61 M reads were obtained. A total of 505,300 SLAFs were detected, of which, 205,299 were polymorphic. Finally, 29,136 SNPs were employed to dissect the population structure, genetic relationships, and genetic diversity. The 284 mango accessions were divided into two major groups: one group consisted mainly of mango accessions from Australia, the United States, Cuba, India, Caribbean, Israel, Pakistan, Guinea, Burma, China, and Sri Lanka, which belonged to the Indian type (P1); the other group contained mango accessions from the Philippines, Thailand, Indonesia, Vietnam, Cambodia, Malaysia, and Singapore, which belonged to Southeast Asian type (P2). Genetic diversity, principal component analysis (PCA), and population structure analyses revealed distinct accession clusters. Current results indicated that the proposed hybridization occurred widely between P1 and P2. Discussion Most of the accessions (80.99%) were of mixed ancestry, perhaps including multiple hybridization events and regional selection, which merits further investigation.
With the rapid development of 5G network and Internet of Things, Clustered Look-Ahead (CLA) technique becomes a promising approach to further accelerate recursive digital filters for real-time ...applications, such as smart robots and automatic driving. However, it is not easy to quickly obtain a stable CLA pipelined VLSI (Very Large Scale Integration) architecture using the existing methods. This paper proposes a CLA Formula to accelerate the VLSI architecture design procedure through rigorous and complete mathematical derivation. Comparing the proposed method with the symbolic approach, experiments reveal that more than half of the software coding time can be saved for the designers, and the execution time of the programs can also be reduced by 168 to 30243 times with the number of pipelined stages ranging from 6 to 96.
Stochastic computing (SC) has been applied on the implementations of complex arithmetic functions. Complicated polynomial-based approximations lead to large hardware complexity of previous SC ...circuits for arithmetic functions. In this paper, a novel piecewise approximation method based on Taylor series expansion is proposed for complex arithmetic functions. Efficient implementations based on unipolar stochastic logic are presented for the monotonic functions. Furthermore, detailed optimization schemes are provided for the non-monotonic functions. Using NAND and AND gates as main computing elements, the optimized hardware architectures have extremely low complexity. The experimental results show that a broad range of arithmetic functions can be implemented with the proposed SC circuits, and the mean absolute errors can achieve the order of 1 × 10-3. Compared with the state-of-the-art works, the approximation precision for some typical functions can be increased by more than 8× with our method. In addition, the proposed circuits outperform the previous methods in hardware complexity and critical path significantly.
We synthesized a novel amphiphilic alternating copolymer brush (AACPB), poly{maleimide-g-poly10-(cholesteryloxycarbonyl)decyl methacrylate}-alt-(styrene-g-poly(ethylene oxide)) ...(P(MI-g-PCholMA)-alt-(St-g-PEO)), by copolymerization of maleimide-terminated poly10-(cholesteryloxycarbonyl)decyl methacrylate (MI-PCholMA) and styrene-terminated poly(ethylene oxide) (St-PEO). The thermal properties of the polymer brushes were investigated by thermogravimetric analysis and differential scanning calorimetry. After solvent and thermal annealing, the AACPB self-assembles into a hierarchically ordered nanostructure. One is the microphase-separated lamellar nanostructure with a 9.66 nm scale. The other is the cholesteryl double-layer smectic A phase (SmAd) with a 5.46 nm scale. The order–disorder transition of the AACPB is associated with the SmAd–isotropic transition. It is the first report on the microphase separation of AACPBs. We can construct ordered nanostructures with a sub-10 nm length scale with AACPBs. After the doping of 0.2 equiv of LiCF3SO3, the d-spacing of the lamellar structure formed by the PCholMA8-alt-PEO25/LiCF3SO3 complex increases because the interaction between Li+ and oxygen atom makes the PEO chains more stretched. Such a structure offers lithium salt-doped PEO nanochannels which can act as pathways for the transport of lithium ion.
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