Showing 19 results for Noise
Khodabandehloo, Mirzakuchaki, Karimi,
Volume 2, Issue 1 (1-2006)
Abstract
The mixed-signal circuits with both analog and digital blocks on a single chip have wide applications in communication and RF circuits. Integrating these two blocks can cause serious problems especially in applications requiring fast digital circuits and high performance analog blocks. Fast switching in digital blocks generates a noise which can be introduced to analog circuits by the common substrate. This noise can decrease the performance of mixed-signal circuits therefore, studying this noise and the way it is transmitted will lead to solutions for reducing it and improving mixed-signal circuit’s performance. In this paper, an efficient model for substrate is extracted from Green’s function in MATLAB environment, and its accuracy is demonstrated. Using a VCO and a multiplier as analog and digital blocks, respectively and simulating them along with the proposed model of the substrate, the effects of substrate noise coupled to analog blocks are shown. Finally, some methods for reducing this noise are applied to the circuit, and the results are compared to each other. The results indicate that using P+ Guard Rings is the best method for reducing substrate noise in the mixed-signal circuits.
S. M. Dehghan, A. Yazdian, M. Mohamadian,
Volume 2, Issue 2 (4-2006)
Abstract
In this paper a hybrid active DC line conditioner for fluctuations and ripples
reduction in voltage and current of DC power systems is proposed. Malfunctions in
operation of equipments and systems which are supplied by low quality distribution power
systems are one of the main effects of DC voltage ripple. In the proposed configuration a
hybrid system including series and shunt active line conditioners for ripple reduction of
load voltage and source current is used. Simulation and experimental results are provided to
show the performance of the proposed configuration in different states.
M. Shams Esfand Abadi, S. Nikbakht,
Volume 7, Issue 2 (6-2011)
Abstract
Two-dimensional (TD) adaptive filtering is a technique that can be applied to many image, and signal processing applications. This paper extends the one-dimensional adaptive filter algorithms to TD structures and the novel TD adaptive filters are established. Based on this extension, the TD variable step-size normalized least mean squares (TD-VSS-NLMS), the TD-VSS affine projection algorithms (TD-VSS-APA), the TD set-membership NLMS (TD-SM-NLMS), the TD-SM-APA, the TD selective partial update NLMS (TD-SPU-NLMS), and the TD-SPU-APA are presented. In TD-VSS adaptive filters, the step-size changes during the adaptation which leads to improve the performance of the algorithms. In TD-SM adaptive filter algorithms, the filter coefficients are not updated at each iteration. Therefore, the computational complexity is reduced. In TD-SPU adaptive algorithms, the filter coefficients are partially updated which reduce the computational complexity. We demonstrate the good performance of the proposed algorithms thorough several simulation results in TD adaptive noise cancellation (TD-ANC) for image restoration. The results are compared with the classical TD adaptive filters such as TD-LMS, TD-NLMS, and TD-APA
R. Mirzalou, A. Nabavi, Gh. Darvish,
Volume 8, Issue 3 (9-2012)
Abstract
This paper presents a new ultra-wideband LNA which employs the complementary derivative superposition method in noise cancellation structure. A pMOS transistor in weak inversion region is employed for simultaneous second- and third-order distortion cancellation. Source-degeneration technique and two shunt inductors are added to improve the performance at high frequencies. The degeneration inductor resonates at fT/2 and realizes a new input matching technique that widens the bandwidth with decreasing its quality factor and input capacitance, while flattens the input resistance and also improves the 1dB Compression Point. The shunt inductors resonate at the center frequency of the band and improve the effective bandwidth of noise/distortion cancellation technique. This LNA has been designed in a 0.18-μm CMOS process and consumes 8.3 mA from 1.8 V power supply. The chip area is 0.55mm2. The noise figure and voltage gain are 4.48-5.18 dB and 13 dB, respectively. S11 is lower than -13.5 dB over 5.8–10.6 GHz and IIP3 is 14.5–17.5 dBm, IIP2 is 14–15.5 dBm. This technique improves IIP3 more than 9dB.
M. H Shakoor, F. Tajeripour,
Volume 11, Issue 3 (9-2015)
Abstract
In this paper, a special preprocessing operations (filter) is proposed to decrease
the effects of noise of textures. This filter using average of circular neighbor points (Cmean)
to reduce noise effect. Comparing this filter with other average filters such as square
mean filter and square median filter indicates that it provides more noise reduction and
increases the classification accuracy. After applying filter to noisy textures some Local
Binary Pattern (LBP) variants are used for feature extraction. The Implementation part for
noisy textures of Outex, UIUC and CUReT datasets shows that using proposed filter
increases the classification accuracy significantly. Furthermore, a simple and new technique
is proposed that increases the speed of c-mean filter noticeably.
M. Safari, M. Eghtesadi, M. R. Mosavi,
Volume 12, Issue 2 (6-2016)
Abstract
In this paper, a new design of concurrent dual-band Low Noise Amplifier (LNA) for multi-band single-channel Global Navigation Satellite System (GNSS) receivers is proposed. This new structure is able to operate concurrently at frequency of 1.2 and 1.57 GHz. Parallel and series resonance parts are employed in the input matching in order to achieve concurrent performance. With respect to used pseudo-differential structure, LNA is basically a single-ended-to-differential conversion and it consequently has no need to balun. In addition, an inductively degenerated cascode approach is employed to have better simultaneous matching and Noise Figure (NF). Simulations are performed with TSMC 0.18 μm technology in ADS software. Results analysis present that LNA achieves input matchings of -11.024 and -13.131 dB, NFs of 2.315 and 2.333 dB, gains of 26.926 and 27.576 dB, P-1dB of -15.3 and -13 dBm, IIP3 of -0.9 and 2.2 dBm at 1.2 and 1.57 GHz, respectively. Besides, LNA consumes 8.32 mA DC current from a 1.8 V supply voltage.
M. Bashirpour, M. Geravanchizadeh,
Volume 12, Issue 3 (9-2016)
Abstract
Automatic recognition of speech emotional states in noisy conditions has become an important research topic in the emotional speech recognition area, in recent years. This paper considers the recognition of emotional states via speech in real environments. For this task, we employ the power normalized cepstral coefficients (PNCC) in a speech emotion recognition system. We investigate its performance in emotion recognition using clean and noisy speech materials and compare it with the performances of the well-known MFCC, LPCC, RASTA-PLP, and also TEMFCC features. Speech samples are extracted from the Berlin emotional speech database (Emo DB) and Persian emotional speech database (Persian ESD) which are corrupted with 4 different noise types under various SNR levels. The experiments are conducted in clean train/noisy test scenarios to simulate practical conditions with noise sources. Simulation results show that higher recognition rates are achieved for PNCC as compared with the conventional features under noisy conditions.
M. Abarzadeh, F. Eshaghi, E. Najafi Aghdam,
Volume 14, Issue 1 (3-2018)
Abstract
This paper proposes an improved control method based on modified Delta-Sigma Modulator (DSM) to enhance transient response and improve harmonic contents of buck DC-DC converter. The main advantages of the proposed method are improving the output voltage frequency spectrum, correction of the output voltage harmonic contents and sideband harmonics, reduction of switching noise peaks at the output voltage, operating buck converter in continuous current mode independent of load current, significant reduction of inductor current ripple, improving the transient response of buck converter and correction of the input current harmonics. This progress is achieved by applying improved control method based on proposed forgetting function to enhance transient response of buck converter and also by using modified DSM to improve harmonic spectrum of the output voltage and reduce inductor current ripples. The simulation results confirm performance and feasibility of the proposed system.
S. M. Razavi, S. M. Razavi,
Volume 15, Issue 3 (9-2019)
Abstract
Probabilistic-based methods have been used for designing noise tolerant circuits recently. In these methods, however, there is not any reliability mechanism that is essential for nanometer digital VLSI circuits. In this paper, we propose a novel method for designing reliable probabilistic-based logic gates. The advantage of the proposed method in comparison with previous probabilistic-based methods is its ultra-high reliability. The proposed method benefits from Markov random field (MRF) as a probabilistic framework and triple modular redundancy (TMR) as a reliability mechanism. A NAND gate is used to show the design methodology. The simulation results verify the noise immunity of the proposed MRF-based gate in the presence of noise. In addition, the values from reliability estimation program show the reliability of 0.99999999 and 0.99941316 for transistor failure rates of 0.0001 and 0.001, respectively, which are much better as compared with previous reported MRF-based designs.
S. Juneja, R. Sharma,
Volume 15, Issue 4 (12-2019)
Abstract
Design of Global Positioning System (GPS) receiver with a low noise amplifier (LNA) in the front end remains a major design requirement for the success of modern day navigation and communication system. Any LNA is expected to meet the requirements like its ability to add the least amount of noise while providing sufficient gain, perfect input and output matching, and high linearity. However, most of the reported designs of LNAs present the need for striking a trade-off between these design parameters in order to obtain the desired performance for a particular RF receiver. This paper presents high gain (21dB), high input matched (-29dB), high reverse isolation (-41dB) and low noise figure (< 2dB) narrowband LNA for extremely low power level GPS L1 band signals broadcasting at 1.57GHz with a channel bandwidth of 10MHz. Inductive source degeneration topology is employed for the design and all the matching inductors in the circuit are used with fixed quality factor (Q) to model the losses for better tuning and matching. The design is carried out on Cadence Virtuoso Tool version IC6.1.6 and Spectre version MMSIM13.1 at 0.18µm technology node using a generic process development kit. Detailed mathematical analysis of the design is done and all the DC parameters like values of transconductance, gate source capacitance, drain source voltage, drain current, etc. are reported. Graphical analysis using Smith chart is carried out to present the results and to bring forth the trade-offs involved in the design. LNA draws 5mA current from 1.2V supply voltage and offers good linearity that is sufficient for GPS application and is measured by input intercept point 3 (IIP3 < ‑4dBm).
H. Shadfar, H. R. Izadfar,
Volume 16, Issue 1 (3-2020)
Abstract
Single-phase induction motors have a wide range of domestic and industrial applications. These motors have a squirrel cage rotor and their stator usually has two windings: main and auxiliary. The use of auxiliary winding in the structure of single-phase induction motors creates two unbalance and asymmetric phases. This causes to increase the spatial harmonics of the field in the air gap, and also useless electromagnetic forces. The purpose of this paper is the reduction of the electromagnetic forces in single-phase induction motors, focusing on the effect of the stator winding distribution. For this purpose, two new and different winding distributions for the motors used in the water coolers will be provided. The produced electromagnetic forces in several conventional single-phase induction motors will be compared with new and conventional windings by means of numerical methods. Numerical analysis is performed by Maxwell software. The results of this analysis indicate improvements in the quality of the performance of these motors in the presence of the provided windings.
M. Monemizadeh, H. Fehri, Gh. Abed Hodtani, S. Hajizadeh,
Volume 16, Issue 2 (6-2020)
Abstract
Communication in the presence of a priori known interference at the encoder has gained great interest because of its many practical applications. In this paper, additive exponential noise channel with additive exponential interference (AENC-AEI) known non-causally at the transmitter is introduced as a new variant of such communication scenarios. First, it is shown that the additive Gaussian channel with a priori known interference at the encoder when the transmitter suffers from a fast-varying phase noise can be modeled by the AENC-AEI. Then, capacity bounds for this channel under a non-negativity constraint as well as a mean value constraint on input are derived. Finally, it is shown both analytically and numerically that the upper and lower bounds coincide at high signal to noise ratios (SNRs), and therefore, the capacity of the AENC-AEI at high SNRs is obtained. Interestingly, this high SNR-capacity has a simple closed-form expression and is independent of the interference mean, analogous to its Gaussian counterpart.
S. Shadpey, M. Sarlak,
Volume 16, Issue 4 (12-2020)
Abstract
This paper presents a pattern recognition-based scheme for detection of islanding conditions in synchronous- based distributed generation (DG) systems. The main idea behind the proposed scheme is the use of spatial features of system parameters such as the frequency, magnitude of positive sequence voltage, etc. In this study, the system parameters sampled at the point of common coupling (PCC) were analyzed using reduced-noise morphological gradient (RNMG) tool, first. Then, the spatial features of the RNMG magnitudes were calculated. Next, to optimize and increase the ability of the proposed scheme for islanding detection, the best features with a much discriminating power were selected based on separability index (SI) calculation. Finally, to distinguish the islanding conditions from the other normal operation conditions, a support vector machine (SVM) classifier was trained based on the selected features. To investigate the power of the proposed scheme for islanding detection, the results of examinations on the various islanding conditions including system loading and grid operating state were presented. These results show that the proposed algorithm reliably detect the islanding condition within 32.7 ms.
P. Vahedi, B. Ganji, E. Afjei,
Volume 16, Issue 4 (12-2020)
Abstract
Using ANSYS finite element (FE) package, a multi-physics simulation model based on finite element method (FEM) is introduced for the multi-layer switched reluctance motor (SRM) in the present paper. The simulation model is created totally in ANSYS parametric design language (APDL) as a parametric model usable for various conventional types of this motor and it is included electromagnetic, thermal, and structural analyses. The static characteristic of flux-linkage with a phase, phase current waveform, instantaneous torque, and electromagnetic losses are predicted using the developed electromagnetic model. Carrying out 3D FE thermal analysis, the temperature rise due to the calculated core and copper losses is predicted in the developed thermal model. The transient, modal and harmonic analyses are done in the introduced structural model to determine the mode shapes, natural frequencies, displacement, and sound pressure level (SPL) in both time and frequency domains. In order to evaluate the developed simulation model, it is applied to a typical multi-layer SRM, and simulation results related to all the above-mentioned analyses are presented.
S. M. Razavi, S. M. Razavi,
Volume 16, Issue 4 (12-2020)
Abstract
The Markov random field (MRF) theory has been accepted as a highly effective framework for designing noise-tolerant nanometer digital VLSI circuits. In MRF-based design, proper feedback lines are used to control noise and keep the circuits in their valid states. However, this methodology has encountered two major problems that have limited the application of highly noise immune MRF-based circuits. First, excessive hardware overhead that imposes a great cost, power consumption and propagation delay on the circuits and second, separate implementation of feedback lines that adds further delay to the circuits. In this paper, we propose a novel approach for minimal-cost inherent-feedback implementation of low-power MRF-based logic gates. The simulation results, which are based on 32nm BSIM4 models, demonstrate that besides excellent noise immunity of the proposed method, it has the least propagation delay in comparison with all of the previously reported MRF-based gates due to its inherent feedbacks. In addition, the proposed method outperforms competing ones, which have comparable noise immunity, in other circuit metrics like cost and power consumption. Specifically, the proposed method achieves at least 18%, 29%, and 39% reductions in cost, delay and power consumption with considerable noise immunity improvement compared with competing methods.
M. Petrov,
Volume 17, Issue 1 (3-2021)
Abstract
The noise in reconstructed slices of X-ray Computed Tomography (CT) is of unknown distribution, non-stationary, oriented and difficult to distinguish from main structural information. This requires the development of special post-processing methods based on the local statistical evaluation of the noise component. This paper presents an adaptive method of reducing noise in CT images employing the shearlet domain in order to obtain such an estimate. The algorithm for statistical noise assessment takes into account the distribution of signal energy in different scales and directions. The method efficiently uses the strong targeted sensitivity of shearlet systems in order to reflect more accurately the anisotropic information in the image. Because of the complex characteristics of the noise in these images, the threshold constant is determined by means of the relative entropy change criterion. The comparative analysis, which has been conducted, shows that the proposed method achieves higher values for the Peak Signal-to-Noise Ratio (PSNR), as well as lower values for the Mean Squared Error (MSE), in comparison with the other methods considered. For the MATLAB’S Shepp Logan Phantom test image, the numerical value of this superiority is on average more than 23% for the first quantitative measure, and 37% for the second. Its efficiency, which is greater than that of the wavelet-based method, is confirmed by the results obtained – the edges have been preserved during noise reduction in real CT images.
H. Ghonoodi, M. Hadjmohammadi,
Volume 17, Issue 4 (12-2021)
Abstract
In this paper a novel design is presented for a dual-band LC oscillator, using an analytical approach. The core of the proposed circuit contains a cross-coupled CMOS LC oscillator with two serried LC tanks so that the inductors of these tanks have mutual inductance. There are some switches in the circuit that directly changes mutual inductance to produce two different frequencies. This technique increases the oscillation amplitude in the same power consumption that leads to the decrement of phase noise. In other words, using two serried LC tank compensates the injected phase noise from switches. The symmetrical structure is another advantage of the presented design that makes it possible to be used in multiphase oscillator. To assess the quality of the proposed circuit, a dual-band quadrature LC oscillator has been designed to oscillate at 3.6 GHz and 6.4 GHz with 1.5 V supply and 1 mA current consumption, with TSMC 0.18 CMOS practical model. Lastly, simulation results confirm the correctness of analytical results and high proficiency of the proposed design.
B. Dorostkar Yaghouti,
Volume 19, Issue 2 (6-2023)
Abstract
By increasing the transceiver devices within the 3.1 to 10.6 GHz frequency band, the interferers and strong blockers from different equipment degraded the main received signals, so linearity performance becomes more notable. In this paper, a two-path low noise amplifier (LNA) is proposed for satisfying the overall efficiency of the Ultra-wideband (UWB) radar used in vital sign detection, precise indoor localization, and high data rate wireless communications. A novel high linear circuit is recommended based on Complementary Derivative Superposition (CDS) and Post Distortion (PD) techniques. High pass filter and inductive source degeneration structured input impedance matching. Post layout results of the designed UWB-LNA in 180-nm CMOS represented the average of third-order Intercept Point (IIP3) is 8.1 dBm, S21 is 11 dB and, S11 is below -10 dB. The minimum noise figure (NF) is 3.11 dB. The circuit draws 12.7 mA at 1.4-V. The chip area is 930 µm × 1090 µm. The proposed design in this work exhibits higher FOM compared to similar LNAs, It is clear, high-linearity performance in total bandwidth is an advantage compared to recent articles.
O. Mahmoudi Mehr, M. R. Mohammadi, M. Soryani,
Volume 19, Issue 3 (9-2023)
Abstract
Speckle noise is an inherent artifact appearing in medical images that significantly lowers the quality and accuracy of diagnosis and treatment. Therefore, speckle reduction is considered as an essential step before processing and analyzing the ultrasound images. In this paper, we propose an ultrasound speckle reduction method based on speckle noise model estimation using a deep learning architecture called “speckle noise-based inception convolutional denoising neural network" (SNICDNN). Regarding the complicated nature of speckle noise, an inception module is added to the first layer to boost the power of feature extraction. Reconstruction of the despeckled image is performed by introducing a mathematical method based on solving a quadratic equation and applying an image-based inception convolutional denoising autoencoder (IICDAE). The results of various quantitative and qualitative evaluations on real ultrasound images demonstrate that SNICDNN outperforms the state-of-the-art methods for ultrasound despeckling. SNICDNN achieves 0.4579 dB and 0.0100 additional gains on average for PSNR and SSIM, respectively, compared to other methods. Denoising ultrasound based on its noise model estimation is not only a novel approach in comparison to traditional denoising autoencoder models but also due to the fact that it uses mathematical solutions to recover denoised images, SNICDNN shows a greater power in ultrasound despeckling.
