Active Comb Filter Using Operational Transconductance Amplifier

Many studies have been devoted to the adaptive power-line interference (PLI) filter design for ECG signal processing. However, almost all existing PLI suppression filters are developed for applications in which the presence of PLI noise is assumed a priori. Indiscriminate application of PLI suppression over an ECG signal that is free of PLI noise may deform ECG morphology, and even cause degraded performance of subsequent processing. To date, little work has been done on the possibility of ECG signal degradation by such filtering operation and the impact on further processing. In order to evaluate the difference between the original and the filtered pattern, this study proposes quantitative evaluation measures. The assessments include convergence time, the frequency tracking efficiency, the execution time and the relative statistics in time and frequency domain. Extensive experiments have been done with artificially and practically corrupted ECG signals for four existing PLI adaptive filtering techniques (Ahlstrom and Tompkinspsila, Pei and Tsengpsilas, Sopsilas and Ziarani and Konradpsilas algorithm). The results reveal that ECG signal distortion resulted from these existing adaptive filters. None of the existing algorithms outperform the others in all assessments. The proposed evaluation measures can also be used for the performance evaluation of the other types of artifact suppression, such as the baseline wander and EMG corruption contaminated in ECG, after minor modification. The proposed measures also make the optimal filter design under different constraints possible for ECG signal processing.

With the rapid development of social economy, electric energy plays an indispensable role in social life and has become an important symbol of the country’s comprehensive national strength. However, with the rapid development of power electronic technology, many nonlinear loads appear in the power system, which has become the most important harmonic source in the power system. Harmonics will not only affect the normal operation of various electrical equipment, but also damage the peripheral communication system and equipment of public power grid. Therefore, we must control the harmonics in the power grid. The traditional treatment scheme is to use LC passive filter (PF), but it can only filter out harmonics of a specific number of times. In addition,it is sensitive to power grid parameters, may produce resonance, so that the harmonics are amplified, and the volume of the filter device is huge. In order to overcome the above problems, active power filter (APF) appears, which can dynamically compensate harmonics according to harmonic frequency and size, and has excellent flexibility and practicability. However, in terms of cost, the cost of APF with the same capacity is much higher than that of PF. Therefore, based on the respective characteristics of PF and APF, this paper makes an in-depth research and design of hybrid active power filter (HAPF). In this system, the passive filter completes the main harmonic compensation and reactive power improvement, while the active filter is used to help the passive filter overcome the disadvantage of easy resonance.

This paper presents the design and simulation of a single-phase shunt active power filter for harmonic and power factor compensation of multiple nonlinear loads. The system is modeled in Matlab Simulink to consist of an uncontrolled rectifier and an AC controller as the nonlinear loads, with an active filter to compensate for the harmonic current injected by the load. The active filter is based on a full-bridge single-phase inverter. The design of the active filter controller is based on time-domain method that consists of three main tasks; to identify the harmonic content and form a synchronized reference, to provide closed-loop control to force the current of the active filter to follow the reference and to regulate the capacitor DC voltage. The spectral analysis of the supply current shows the harmonics produced by the load has been successfully compensated by the active filter. The effect of varying the switching frequency on the performance of the active filter is also presented.

Design and implementation of a multiband digital filter using FPGA to extract the ECG signal in the presence of different interference signals

Digital filters, as one of the most essential tools for signal processing, are often used in ECG signal processing. The hardware implementation of conventional digital filters relies on a hybrid device composed of a digital multiplier, an adder, and a delay unit. However, it has characteristics of a large amount of calculation, complex structure, and high overhead. With the development of computer technology, software implementation of signal processing and filter designing has been increasingly used. As a typical physiological signal, an ECG signal is characterized by a weak signal, complex noise, broad frequency spectrum, and little data sampling. The ECG filter designed by software can effectively weaken the useless noise in ECG signals, helping medical personnel obtain relevant information on patients’ symptoms and realize the diagnosis of diseases.

Component value selection for active filters based on minimization of GSP and E12 compatible using Grey Wolf and Particle Swarm Optimization

Visible light communication with LED is an important ICT for the ubiquitous network society. However visible light communication has the speed limit in the conventional blinking LED method. Therefore an active spectral filter would be useful in order to input information signals onto the LED spectrum. Plasmonic spectral filter based on a metalinsulator- metal (MIM) structure is one of the candidates of such active filter. We will explain our progress of fabrication of the MIM structures with the vacuum deposition technique and compare their absorption properties with the theoretical prediction.

This paper presents the design and implementation of a single-phase parallel active filter for harmonic compensation. The idea of the work is to optimize the processed power by the active single-phase filter restricting the compensation only to harmonic currents without processing the linear reactive one. The linear reactive current can be compensated by capacitors, since this method is extremely widespread and efficient for this type of compensation. It is made a comparison study of processed power by a conventional active power filter compensating the entirely reactive power and another compensating only the harmonic contents. It is presented the control methodology employed, the power circuit design and the results obtained through a 500VA experimental prototype.

The aim of this paper is to introduce a methodology to design an active DM filter at the input side of AC-DC converters to cancel current ripples and DM EMI noise. The boost PFC AC-DC converter's noise characteristic was first analyzed. The active filter topologies are designed based on the identified characteristics of the AC-DC converters. Several design issues such as thermal run away, DC offset, stability and compensation design, and the number of preamplifier stages are to be addressed in detail. Both simulations and experiments were conducted to validate the proposed methodology. It is found that the proposed design methodology can meet the design objective and the big stability challenge for the DM active filter of AC-DC converters.

This paper presents a FIR Equiripple low pass filter design based on FPGA for eliminating high frequency noise from ECG signal. The filter architecture is partly serial and it is designed in MATLAB using direct form symmetric structure because implementation cost of symmetric structure is low as compared to direct form. The filter is designed using 16 bit input output precision. The filter design is synthesized on 2vp30fg676 and 5vlx50tff1136 device. Verilog Hardware Description Language (VHDL) is used for implementation of filter design on FPGA. Since coefficients are quantized in MATLAB to reduce design area and Xilinx 10.1 is used to simulate and synthesis the filter. Device utilization summary and speed comparison shows that filter design based on Virtex 5 is most speed efficient and device utilization ratio of partly serial architecture is better than fully parallel architecture.

Design of ANC filter using modified cuckoo search technique for ECG signal enhancement

In order to enhance the ECG signal, this paper uses independent component analysis to process the mixed noise output signal. Firstly, a simulator based on Fourier series is used to simulate an ECG signal and the noise signal of power frequency signal is replaced by sinusoidal signal, and the two signals are randomly mixed. Then the mixed signals are separated by FastICA algorithm, and the ideal separation results are obtained. The results show that the correlation coefficient between the separated ECG signal and the original ECG signal is 0.9659, which indicates that the FastICA algorithm is feasible for medical signal enhancement.

This article presents the design and implementation of a low power FPGA-based optimal multiband filter with Spline function for denoising ECG signals. The proposed multiband filter design utilizes least mean square algorithm to determine the optimal filter coefficients for multiple frequency bands, while the Spline function is used to interpolate the filter coefficients within each band to achieve a smooth transition between adjacent bands. The experimental work is carried out with ECGID database and it shows that the proposed filter outperforms in terms of benchmark performance matrices SNR, MSE, CC and PRD. The filter is implemented on a low power FPGA platform, which allows for real-time processing of ECG signals with low power consumption. The experimental results are analyzed and compared for different architecture using the MATLAB and XILINX VIVADO tools. The serial architecture of proposed filter design is implemented on Artix 7 (XC7A35T) EDGE Board, utilizing 1932 LUT, 5299 FF, 1 DSP block and 0.158 W on-chip power. The experimental results indicate that the proposed filter design approach is efficient, effective, and suitable for implementation in compact biomedical devices.

This article has demonstrated the feasibility of a three phase active filter based on a half-bridge topology. Design guidelines for the power circuit have been derived and applied to a 5 kVA IGBT laboratory prototype. In the single phase mode, the active filter can reduce the low frequency harmonic content in the AC line to below 1% excluding the harmonics due to switching action of the converter. In the three phase mode, line currents are corrected under balanced and unbalanced conditions. The neutral current is reduced significantly.

A brief review to production and the historical development of the active filter technology are introduced. Then the electric current detection method based on the instant reactive power theory is discussed in detail and other electric current detection methods are briefly introduced. It has provided some references to the electric current detection algorithm choice for the design of the active filter.