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Joint Sample Position Based Noise Filtering and Mean Shift Clustering for Imbalanced Classification Learning
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作者 Lilong Duan Wei Xue +1 位作者 Jun Huang Xiao Zheng 《Tsinghua Science and Technology》 SCIE EI CAS CSCD 2024年第1期216-231,共16页
The problem of imbalanced data classification learning has received much attention.Conventional classification algorithms are susceptible to data skew to favor majority samples and ignore minority samples.Majority wei... The problem of imbalanced data classification learning has received much attention.Conventional classification algorithms are susceptible to data skew to favor majority samples and ignore minority samples.Majority weighted minority oversampling technique(MWMOTE)is an effective approach to solve this problem,however,it may suffer from the shortcomings of inadequate noise filtering and synthesizing the same samples as the original minority data.To this end,we propose an improved MWMOTE method named joint sample position based noise filtering and mean shift clustering(SPMSC)to solve these problems.Firstly,in order to effectively eliminate the effect of noisy samples,SPMsC uses a new noise filtering mechanism to determine whether a minority sample is noisy or not based on its position and distribution relative to the majority sample.Note that MWMOTE may generate duplicate samples,we then employ the mean shift algorithm to cluster minority samples to reduce synthetic replicate samples.Finally,data cleaning is performed on the processed data to further eliminate class overlap.Experiments on extensive benchmark datasets demonstrate the effectiveness of SPMsC compared with other sampling methods. 展开更多
关键词 imbalanced data classification OVERSAMPLING noise filtering CLUSTERING
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YOLO-RLC:An Advanced Target-Detection Algorithm for Surface Defects of Printed Circuit Boards Based on YOLOv5
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作者 Yuanyuan Wang Jialong Huang +4 位作者 Md Sharid Kayes Dipu Hu Zhao Shangbing Gao Haiyan Zhang Pinrong Lv 《Computers, Materials & Continua》 SCIE EI 2024年第9期4973-4995,共23页
Printed circuit boards(PCBs)provide stable connections between electronic components.However,defective printed circuit boards may cause the entire equipment system to malfunction,resulting in incalculable losses.There... Printed circuit boards(PCBs)provide stable connections between electronic components.However,defective printed circuit boards may cause the entire equipment system to malfunction,resulting in incalculable losses.Therefore,it is crucial to detect defective printed circuit boards during the generation process.Traditional detection methods have low accuracy in detecting subtle defects in complex background environments.In order to improve the detection accuracy of surface defects on industrial printed circuit boards,this paper proposes a residual large kernel network based on YOLOv5(You Only Look Once version 5)for PCBs surface defect detection,called YOLO-RLC(You Only Look Once-Residual Large Kernel).Build a deep large kernel backbone to expand the effective field of view,capture global informationmore efficiently,and use 1×1 convolutions to balance the depth of the model,improving feature extraction efficiency through reparameterization methods.The neck network introduces a bidirectional weighted feature fusion network,combined with a brand-new noise filter and feature enhancement extractor,to eliminate noise information generated by information fusion and recalibrate information from different channels to improve the quality of deep features.Simplify the aspect ratio of the bounding box to alleviate the issue of specificity values.After training and testing on the PCB defect dataset,our method achieved an average accuracy of 97.3%(mAP50)after multiple experiments,which is 4.1%higher than YOLOv5-S,with an average accuracy of 97.6%and an Frames Per Second of 76.7.The comparative analysis also proves the superior performance and feasibility of YOLO-RLC in PCB defect detection. 展开更多
关键词 Deep learning PCB defect detection large kernel noise filtering weighted fusion YOLO
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A 4.8GHz CMOS Fully Integrated LC Balanced Oscillator with Symmetrical Noise Filter Technique and Large Tuning Range
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作者 杨丰林 张钊锋 +1 位作者 李宝骐 闵昊 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2005年第3期448-454,共7页
This paper presents a fully integrated 4 8GHz VCO with an invention——symmetrical noise filter technique.This VCO,with relatively low phase noise and large tuning range of 716MHz,is fabricated with the 0 25μm SMIC... This paper presents a fully integrated 4 8GHz VCO with an invention——symmetrical noise filter technique.This VCO,with relatively low phase noise and large tuning range of 716MHz,is fabricated with the 0 25μm SMIC CMOS process.The oscillator consumes 6mA from 2 5V supply.Another conventional VCO is also designed and simulated without symmetrical noise filter on the same process,which also consumes 6mA current and is with the same tuning.Simulation result describes that the first VCO’ phase noise is 6dBc/Hz better than the latter’s at the same offset frequency from 4 8GHz.Measured phase noise at 1MHz away from the carrier in this 4 8GHz VCO with symmetrical noise filter is -123 66dBc/Hz.This design is suitable for the usage in a phase locked loop and other consumer electronics.It is amenable for future technologies and allows easy porting to different CMOS manufacturing process. 展开更多
关键词 VCO symmetrical noise filter radio frequency INDUCTOR switch capacitor
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Influence of image data set noise on classification with a convolutional network 被引量:2
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作者 Wei Tao Shuai Liguo Zhang Yulu 《Journal of Southeast University(English Edition)》 EI CAS 2019年第1期51-56,共6页
To evaluate the influence of data set noise, the network in network(NIN) model is introduced and the negative effects of different types and proportions of noise on deep convolutional models are studied. Different typ... To evaluate the influence of data set noise, the network in network(NIN) model is introduced and the negative effects of different types and proportions of noise on deep convolutional models are studied. Different types and proportions of data noise are added to two reference data sets, Cifar-10 and Cifar-100. Then, this data containing noise is used to train deep convolutional models and classify the validation data set. The experimental results show that the noise in the data set has obvious adverse effects on deep convolutional network classification models. The adverse effects of random noise are small, but the cross-category noise among categories can significantly reduce the recognition ability of the model. Therefore, a solution is proposed to improve the quality of the data sets that are mixed into a single noise category. The model trained with a data set containing noise is used to evaluate the current training data and reclassify the categories of the anomalies to form a new data set. Repeating the above steps can greatly reduce the noise ratio, so the influence of cross-category noise can be effectively avoided. 展开更多
关键词 image recognition data set noise deep convolutional network filtering of cross-category noise
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Noise level estimation method with application to EMD-based signal denoising 被引量:3
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作者 Xiaoyu Li Jing Jin +1 位作者 Yi Shen Yipeng Liu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2016年第4期763-771,共9页
This paper proposes a new signal noise level estimation approach by local regions. The estimated noise variance is applied as the threshold for an improved empirical mode decomposition(EMD) based signal denoising me... This paper proposes a new signal noise level estimation approach by local regions. The estimated noise variance is applied as the threshold for an improved empirical mode decomposition(EMD) based signal denoising method. The proposed estimation method can effectively extract the candidate regions for the noise level estimation by measuring the correlation coefficient between noisy signal and a Gaussian filtered signal. For the improved EMD based method, the situation of decomposed intrinsic mode function(IMFs) which contains noise and signal simultaneously are taken into account. Experimental results from two simulated signals and an X-ray pulsar signal demonstrate that the proposed method can achieve better performance than the conventional EMD and wavelet transform(WT) based denoising methods. 展开更多
关键词 signal denoising empirical mode decomposition(EMD) Gaussian filter correlation coefficient noise level estimation
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Stochastic Response Analysis of Piled Offshore Platform Excited by Stationary Filtered White Noise
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作者 Luo, CX Wu, ZP 《China Ocean Engineering》 SCIE EI 1997年第1期29-42,共14页
In this paper, the analysis method of stochastic response of piled offshore platform excited by stationary filtered white noise is presented. With this method, the strong ground motion is considered as three direction... In this paper, the analysis method of stochastic response of piled offshore platform excited by stationary filtered white noise is presented. With this method, the strong ground motion is considered as three direction stationary filtered white noise process, the theoretic solutions of three special integration equations are derived with the residue theorem, and the expression of response nodal displacements and member forces of offshore platform excited by the stationary filtered white noise is put forward. The stochastic response of a piled offshore platform excited by the stationary filtered white noise, which is located 114.3 m in water depth, is computed. The results are compared with those obtained with the response spectrum analysis method and the stationary white noise model analysis method, and the corresponding conclusion is drawn. 展开更多
关键词 stochastic response piled offshore platform stationary filtered white noise stochastic model response spectrum
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THE EFFECT OF COUPLED FEEDBACK ON NOISE FILTERING IN SIGNAL TRANSDUCTION NETWORKS
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作者 Dengyu LIU Xiao CHANG +2 位作者 Zengrong LIU Luonan CHEN Ruiqi WANG 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2010年第5期942-950,共9页
Many interacting biomolecular components in cells form different positive or negative feedback loops. When biological signals transduce through cascades consisting of various loops they will be affected or even distor... Many interacting biomolecular components in cells form different positive or negative feedback loops. When biological signals transduce through cascades consisting of various loops they will be affected or even distorted. Especially, how to process various signals buried in various intrinsic and extrinsic noises is an important issue. This paper analyzes how the response time influences noise filtering ability and how to enhance the ability by coupling different feedback loops. A parameter to measure the response time of the signal transduction, i.e., τ0.9, and its relationship between the response time and noise filtering will be discussed. The authors show clearly that the longer the response time is, the better the ability to filter noises will be. Therefore, to enhance the ability to filter noises, the authors can prolong the response time by coupling different positive or negative feedback loops. The results provide a possible approach to enhance the ability to filter noises in larger biomolecular networks. 展开更多
关键词 Coupled feedback filtering noises response time signal cycle.
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An Approach Using Fuzzy Sets and Boosting Techniques to Predict Liver Disease 被引量:4
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作者 Pushpendra Kumar Ramjeevan Singh Thakur 《Computers, Materials & Continua》 SCIE EI 2021年第9期3513-3529,共17页
The aim of this research is to develop a mechanism to help medical practitioners predict and diagnose liver disease.Several systems have been proposed to help medical experts by diminishing error and increasing accura... The aim of this research is to develop a mechanism to help medical practitioners predict and diagnose liver disease.Several systems have been proposed to help medical experts by diminishing error and increasing accuracy in diagnosing and predicting diseases.Among many existing methods,a few have considered the class imbalance issues of liver disorder datasets.As all the samples of liver disorder datasets are not useful,they do not contribute to learning about classifiers.A few samples might be redundant,which can increase the computational cost and affect the performance of the classifier.In this paper,a model has been proposed that combines noise filter,fuzzy sets,and boosting techniques(NFFBTs)for liver disease prediction.Firstly,the noise filter(NF)eliminates the outliers from the minority class and removes the outlier and redundant pair from the majority class.Secondly,the fuzzy set concept is applied to handle uncertainty in datasets.Thirdly,the AdaBoost boosting algorithm is trained with several learners viz,random forest(RF),support vector machine(SVM),logistic regression(LR),and naive Bayes(NB).The proposed NFFBT prediction system was applied to two datasets(i.e.,ILPD and MPRLPD)and found that AdaBoost with RF yielded 90.65%and 98.95%accuracy and F1 scores of 92.09%and 99.24%over ILPD and MPRLPD datasets,respectively. 展开更多
关键词 Fuzzy set imbalanced data liver disease prediction machine learning noise filter
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Improving Software Quality Prediction by Noise Filtering Techniques 被引量:3
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作者 Taghi M.Khoshgoftaar Pierre Rebours 《Journal of Computer Science & Technology》 SCIE EI CSCD 2007年第3期387-396,共10页
Accuracy of machine learners is affected by quality of the data the learners are induced on. In this paper, quality of the training dataset is improved by removing instances detected as noisy by the Partitioning Filte... Accuracy of machine learners is affected by quality of the data the learners are induced on. In this paper, quality of the training dataset is improved by removing instances detected as noisy by the Partitioning Filter. The fit dataset is first split into subsets, and different base learners are induced on each of these splits. The predictions are combined in such a way that an instance is identified as noisy if it is misclassified by a certain number of base learners. Two versions of the Partitioning Filter are used: Multiple-Partitioning Filter and Iterative-Partitioning Filter. The number of instances removed by the filters is tuned by the voting scheme of the filter and the number of iterations. The primary aim of this study is to compare the predictive performances of the final models built on the filtered and the un-filtered training datasets. A case study of software measurement data of a high assurance software project is performed. It is shown that predictive performances of models built on the filtered fit datasets and evaluated on a noisy test dataset are generally better than those built on the noisy (un-filtered) fit dataset. However, predictive performance based on certain aggressive filters is affected by presence of noise in the evaluation dataset. 展开更多
关键词 noise filtering data quality software quality classification expected cost of misclassification voting expert
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Multi-Level Fusion in Ultrasound for Cancer Detection Based on Uniform LBP Features 被引量:1
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作者 Diyar Qader Zeebaree Adnan Mohsin Abdulazeez +2 位作者 Dilovan Asaad Zebari Habibollah Haron Haza Nuzly Abdull Hamed 《Computers, Materials & Continua》 SCIE EI 2021年第3期3363-3382,共20页
Collective improvement in the acceptable or desirable accuracy level of breast cancer image-related pattern recognition using various schemes remains challenging.Despite the combination of multiple schemes to achieve ... Collective improvement in the acceptable or desirable accuracy level of breast cancer image-related pattern recognition using various schemes remains challenging.Despite the combination of multiple schemes to achieve superior ultrasound image pattern recognition by reducing the speckle noise,an enhanced technique is not achieved.The purpose of this study is to introduce a features-based fusion scheme based on enhancement uniform-Local Binary Pattern(LBP)and filtered noise reduction.To surmount the above limitations and achieve the aim of the study,a new descriptor that enhances the LBP features based on the new threshold has been proposed.This paper proposes a multi-level fusion scheme for the auto-classification of the static ultrasound images of breast cancer,which was attained in two stages.First,several images were generated from a single image using the pre-processing method.Themedian andWiener filterswere utilized to lessen the speckle noise and enhance the ultrasound image texture.This strategy allowed the extraction of a powerful feature by reducing the overlap between the benign and malignant image classes.Second,the fusion mechanism allowed the production of diverse features from different filtered images.The feasibility of using the LBP-based texture feature to categorize the ultrasound images was demonstrated.The effectiveness of the proposed scheme is tested on 250 ultrasound images comprising 100 and 150 benign and malignant images,respectively.The proposed method achieved very high accuracy(98%),sensitivity(98%),and specificity(99%).As a result,the fusion process that can help achieve a powerful decision based on different features produced from different filtered images improved the results of the new descriptor of LBP features in terms of accuracy,sensitivity,and specificity. 展开更多
关键词 Breast cancer ultrasound image local binary pattern feature extraction noise reduction filters FUSION
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EFFICIENT IMAGE SEGMENTATION FOR SEMANTIC OBJECT GENERATION 被引量:1
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作者 Chen Xiaotang Yu Yinglin (Dept. of Comm. & Info. Eng., South China Univ. of Technology, Guangzhou 510640) 《Journal of Electronics(China)》 2002年第4期420-425,共6页
This letter presents an efficient and simple image segmentation method for semantic object spatial segmentation. First, the image is filtered using contour-preserving filters. Then it is quasi-flat labeled. The small ... This letter presents an efficient and simple image segmentation method for semantic object spatial segmentation. First, the image is filtered using contour-preserving filters. Then it is quasi-flat labeled. The small regions near the contour are classified as uncertain regions and are eliminated by region growing and merging. Further region merging is used to reduce the region number. The simulation results show its efficiency and simplicity. It can preserve the semantic object shape while emphasize on the perceptual complex part of the object. So it conforms to the human visual perception very well. 展开更多
关键词 Image segmentation Semantic object Contour-preserving noise filtering Quasi-flat regions labeling Region merging
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Trigger and noise filtering algorithms for the LHAASO water Cherenkov detector array 被引量:1
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作者 Xiao-Jie Wang Zhi-Guo Yao +8 位作者 Min Zha Ming-Jun Chen Bo Gao De-Zhi Huang Hui-Cai Li Jin-Yan Liu Wen-Ying Liao Han-Rong Wu For the LHAASO collaboration 《Radiation Detection Technology and Methods》 2017年第2期37-50,共14页
Introduction The Large High Altitude Air Shower Observatory(LHAASO)will be constructed at Mt.Haizishan,Sichuan Province,China.Among several detector components of the LHAASO,the Water Cherenkov Detector Array(WCDA)is ... Introduction The Large High Altitude Air Shower Observatory(LHAASO)will be constructed at Mt.Haizishan,Sichuan Province,China.Among several detector components of the LHAASO,the Water Cherenkov Detector Array(WCDA)is of great importance for gamma-ray astronomy from 100 GeV to 30 TeV.The single-channel counting rate of a photo-multiplier tube can reach as high as 30-35 kHz,most of them are background noise hits from the low energy cosmic ray showers,bringing a big challenge on data transferring,data storage and event reconstruction.Methods In this paper,a dedicated trigger scheme and a fast noise filtering method aiming to deal with these high rate background noise hits are introduced.These methods are tested with some Monte Carlo simulation data,showing a fair efficiency in filtering background noise hits,while most of the real shower signals are kept.Conclusion This method is proposed to be applied in a stage of the online processing just after the data are acquired in LHAASO-WCDA. 展开更多
关键词 LHAASO-WCDA High level soft trigger Background noise filtering
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Towed line array sonar platform noise suppression based on spatial matrix filtering technology 被引量:5
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作者 HAN Dong LI Jian +2 位作者 KANG Chunyu HUANG Haining LI Qihu 《Chinese Journal of Acoustics》 2013年第4期379-390,共12页
The spatial matrix filter was designed and used for solving the problem to detect a weak target who was influenced by the strong nearby platform noise interference of the towed line array sonar. The MFP technology and... The spatial matrix filter was designed and used for solving the problem to detect a weak target who was influenced by the strong nearby platform noise interference of the towed line array sonar. The MFP technology and the DOA estimation technology were combined together by using the sound propagation characteristics of both target and interference. The spatial matrix filter with platform noise zero response constraint was designed by the near-field platform noise normal modes copy vectors and the far-field plane wave bearing vectors together. The optimal solution of the optimization problem for designing the spatial matrix filter was deduced directly, and it was simplified by the generalized singular value decomposition. The total response error to the plane wave bearing vectors and the total response to the platform noise copy vectors were given. The phenomena that strong interferences existed in the bearing course and blind areas existed after filtering were analyzed by the correlation between the plat- form noise copy vectors and the plane wave bearing vectors. It could be found from simulations that it has less blind area and higher detection ability by using the spatial matrix filtering technology. 展开更多
关键词 LINE Towed line array sonar platform noise suppression based on spatial matrix filtering technology
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Methods of Data Processing for Trace Elements Analysis Using Laser Induced Breakdown Spectroscopy
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作者 王锐 马晓红 +4 位作者 余琦 宋阳 赵华凤 张敏 廖延彪 《Plasma Science and Technology》 SCIE EI CAS CSCD 2015年第11期944-947,共4页
With the development of Laser Induced Breakdown Spectroscopy (LIBS), increasing numbers of researchers have begun to focus on problems of the application. We are not just satisfied with analyzing what kinds of eleme... With the development of Laser Induced Breakdown Spectroscopy (LIBS), increasing numbers of researchers have begun to focus on problems of the application. We are not just satisfied with analyzing what kinds of elements are in the samples but are also eager to accomplish quantitative detection with LIBS. There are several means to improve the limit of detection and stability, which are important to quantitative detection, especially of trace elements, increasing the laser energy and the resolution of spectrometer, using dual pulse setup, vacuuming the ablation environment etc. All of these methods are about to update the hardware system, which is effective but expensive. So we establish the following spectrum data processing methods to improve the trace elements analysis in this paper: spectrum sifting, noise filtering, and peak fitting. There are small algorithms in these three method groups, which we will introduce in detail. Finally, we discuss how these methods affect the results of trace elements detection in an experiment to analyze the lead content in Chinese cabbage. 展开更多
关键词 LIBS data processing limit of detection spectrum sift noise filtering peak fitting
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A Network Model on the Processing of Sound Wave
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作者 李锋 吴国文 《Journal of Donghua University(English Edition)》 EI CAS 2008年第2期225-229,共5页
On the base of auditory neural system, the network model on the processing of the sound wave is presented. The mathematic equation of the network is also discussed. In the network model, in addition to the negative fe... On the base of auditory neural system, the network model on the processing of the sound wave is presented. The mathematic equation of the network is also discussed. In the network model, in addition to the negative feedback of the neural cell in the output layer, the cell in the input layer excites the corresponding cell in the ontput layer meanwhile it inhibits the lateral cells. The network has its advantage on the processing of sound wave. In addition to filter the noise, it can search the significance frequency segments (Barks). The "channel suppresser" feature, the special phenomena of the human ear, is explained based on the model. The learning algorithm of the network model is discussed, too. In the end, an example is introduced about the application of the network. 展开更多
关键词 BIOPHYSICS neural network noise filter speech recognize
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Applying nonlinear filtering in reverberation time measurement under strong background noise
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作者 YU Wuzhou WANG Zuomin (Institute of Acoustics, Tongji University Shanghai 200092) 《Chinese Journal of Acoustics》 1999年第3期253-258,共6页
Nonlinear filtering of impulse response obtained by M-sequence correlation method under strong background noise is presented. The research shows that the new method works very efficiently without the need ... Nonlinear filtering of impulse response obtained by M-sequence correlation method under strong background noise is presented. The research shows that the new method works very efficiently without the need to cut off impulse response data. Even if the ratio of signal to noise is below -15 dB, the same decay curve ranges can still be obtained as when S/N > 40 dB 展开更多
关键词 TIME Applying nonlinear filtering in reverberation time measurement under strong background noise
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A Δ ∑ fractional-N frequency synthesizer for FM tuner using low noise filter and quantization noise suppression technique 被引量:1
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作者 陈铭易 楚晓杰 +2 位作者 于鹏 颜峻 石寅 《Journal of Semiconductors》 EI CAS CSCD 2014年第7期132-138,共7页
A △∑ fractional-N frequency synthesizer fabricated in a 130 nm CMOS technology is presented for the application of an FM tuner. A low noise filter, occupying a small die area and decreasing the output noise, is inte... A △∑ fractional-N frequency synthesizer fabricated in a 130 nm CMOS technology is presented for the application of an FM tuner. A low noise filter, occupying a small die area and decreasing the output noise, is integrated on a chip. A quantization noise suppression technique, using a reduced step size of the frequency divider, is also adopted. The proposed synthesizer needs no off-chip components and occupies an area of 0.7 mm2. The in-band phase noise (from 10 to 100 kHz) below -108 dBc/Hz and out-of-band phase noise of -122.9 dBc/Hz (at 1 MHz offset) are measured with a loop bandwidth of 200 kHz. The quantization noise suppression technique reduces the in-band and out-of band phase noise by 15 dB and 7 dB respectively. The integrated RMS phase error is no more than 0.48°. The proposed synthesizer consumes a total power of 7.4 mW and the frequency resolution is less than 1 Hz. 展开更多
关键词 FM tuner frequency synthesizer low noise filter △∑ modulator quantization noise suppression
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A 55 nm CMOS ΔΣ fractional-N frequency synthesizer for WLAN transceivers with low noise filters
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作者 陈铭易 楚晓杰 +2 位作者 于鹏 颜峻 石寅 《Journal of Semiconductors》 EI CAS CSCD 2013年第10期83-90,共8页
A fully integrated △∑ fractional-N frequency synthesizer fabricated in a 55 nm CMOS technology is presented for the application of IEEE 802.11b/g wireless local area network (WLAN) transceivers. A low noise filter... A fully integrated △∑ fractional-N frequency synthesizer fabricated in a 55 nm CMOS technology is presented for the application of IEEE 802.11b/g wireless local area network (WLAN) transceivers. A low noise filter, occupying a small die area, whose power supply is given by a high PSRR and low noise LDO regulator, is integrated on chip. The proposed synthesizer needs no off-chip components and occupies an area of 0.72 mm^2excluding PAD. Measurement results show that in all channels, the phase noise of the synthesizer achieves -99 dBc/Hz and -119 dBc/Hz in band and out of band respectively with a reference frequency of 40 MHz and a loop bandwidth of 200 kHz. The integrated RMS phase error is no more than 0.6°. The proposed synthesizer consumes a total power of 15.6 mW. 展开更多
关键词 WLAN IEEE 802.11 b/g frequency synthesizer low noise filter △∑ modulator
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Flexible polarization demultiplexing method based on an adaptive process noise covariance Kalman filter
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作者 Jun Ge Lianshan Yan +5 位作者 Anlin Yi Yan Pan Lin Jiang Liangliang Dai Wei Pan Bin Luo 《Chinese Optics Letters》 SCIE EI CAS CSCD 2018年第6期19-23,共5页
A flexible polarization demultiplexing method based on an adaptive Kalman filter(AKF) is proposed in which the process noise covariance has been estimated adaptively. The proposed method may significantly improve th... A flexible polarization demultiplexing method based on an adaptive Kalman filter(AKF) is proposed in which the process noise covariance has been estimated adaptively. The proposed method may significantly improve the adaptive capability of an extended Kalman filter(EKF) by adaptively estimating the unknown process noise covariance. Compared to the conventional EKF, the proposed method can avoid the tedious and time consuming parameter-by-parameter tuning operations. The effectiveness of this method is confirmed experimentally in 128 Gb/s 16 QAM polarization-division-multiplexing(PDM) coherent optical transmission systems. The results illustrate that our proposed AKF has a better tracking accuracy and a faster convergence(about 4 times quicker)compared to a conventional algorithm with optimal process noise covariance. 展开更多
关键词 EKF PDM Flexible polarization demultiplexing method based on an adaptive process noise covariance Kalman filter QAM
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Design of low noise class D amplifiers using an integrated filter
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作者 王海时 张波 《Journal of Semiconductors》 EI CAS CSCD 2012年第11期67-71,共5页
This paper investigates the noise sources in a single-ended class D amplifier(SECDA) and suggests corresponding ways to lower the noise.The total output noise could be expressed as a function of the gain and noises ... This paper investigates the noise sources in a single-ended class D amplifier(SECDA) and suggests corresponding ways to lower the noise.The total output noise could be expressed as a function of the gain and noises from different sources.According to the function,the bias voltage(V_B) is a primary noise source,especially for a SECDA with a large gain.A low noise SECDA is obtained by integrating a filter into the SECDA to lower the noise of the V_B.The filter utilizes an active resister and an 80 pF capacitance to get a 3 Hz pole.A noise test and fast Fourier transform analysis show that the noise performance of this SECDA is the same as that of a SECDA with an external filter. 展开更多
关键词 class D amplifier low noise filter noise derivation
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