Order Low Pass Filter Research Articles

A Subthreshold Buffer-Based Biquadratic Cell and its Application to Biopotential Filter Design

This paper develops a compact power-efficient CMOS buffer to operate as a nanopower lowpass biquadratic cell. Unlike other recently reported CMOS biquads with passband gains that are attenuated by the bulk effect, this biquad attains a near 0-dB passband gain without gain compensation. It acquires the same levels of input and output common-mode voltages making it useful for cascade realization of a higher order lowpass filter. To demonstrate the potential application of the proposed biquad, a fourth-order lowpass filter was designed based on the proposed biquad circuit and fabricated in the 0.35- ${\mu }\text{m}$ CMOS process to serve electrocardiography readout systems. Measurement results show that the filter consumes 4.26-nW static power from a 0.9-V supply providing a 100-Hz cutoff frequency. The prototype chip occupies a silicon area of 0.11 mm2 and contributes an input-referred noise of $80.5~{\mu }\text{V}_{\mathrm {rms}}$ . For a 60-Hz input frequency associated with −50-dB third-order harmonic distortion, a dynamic range of 48.2 dB is achieved. The lowest power supply rejection ratio of 40 dB was obtained at 100 Hz. Compared with the previous state-of-the-art designs in the category of nanopower filters, the proposed filter consumes the least power from the lowest supply voltage.

Charge Pump and Loop Filter for Low Power PLL Using 130nm CMOS Technology

A tri-state charge pump circuit and second order low pass filter circuit were designed to be used in Phase Lock Loop (PLL) system. The proposed design reduces the non-ideal effects such as a current mismatch and charge sharing. Therefore, it can be minimized by providing an equal value for the two switches UP and DOWN. While the charge pump output determines the output condition of the low pass filter. The proposed design have been simulated by using 130nm Complementary Metal Oxide Semiconductor (CMOS) technology in Cadence Tools. The simulation also includes the parameters for tri-state charge pump and second order low pass filter using voltage supply of 1.2 V. The power consumption of the design is 2.07 mW with the output voltage swing from 288 mV to 413.8 mV. The frequency achieved from the proposed design is 4.7 GHz. The total area of the layout that have been measured is 31.4 µm x 22.6 µm (0.7096 mm2). Thus, the proposed design able to achieve the scope of low power consumption and high frequency in smaller technology.

CMOS analog filter design using the Proportional Source Transconductances Integrator

This work assesses the applicability of a compact CMOS current-mode companding integrator in the design of analog continuous-time filters with high linearity. The companding integrator is based on the proportionality between the source transconductances of the input and output MOS transistors and is independent of the inversion level of the devices. The circuit has been designed in CMOS 130 nm technology with approximately 90 μm2 total active area including biasing elements. According to simulation results the integrator performs a useful frequency bandwidth of up to 4 MHz and a third order intermodulation distortion smaller than −47 dB for input amplitudes ranging from 100 nA to 1 μA. The small and large signal responses and the third order intermodulation, among other features, have also been analyzed through simulation for a fourth order low-pass filter and a sixth order bandpass filter. Performance is compared with a CMOS log-domain integrator and filter.

Analysis of the RBF ANN-based classifier for the diagnostics of electronic circuit

<span lang="EN-GB">The paper presents the application of the Radial Basis Function (RBF) Artificial Neural Network (ANN) to the diagnostics of the analog circuit. Such networks are in most cases useful in the approximation tasks as the alternative to multilayered perceptrons (MLP) or Support Vector Machines (SVM). In this work the analysis of various RBF ANN-based classifier configurations for the fault detection and identification module are is conducted. The considered parameters included the optimal number of neurons in the hidden layer, coding schemes for the output layer neurons and operation duration during the training and testing the classifier. The efficiency of the diagnostic system is verified using the fifth order lowpass filter. The circuit was also analyzed in terms of the testability, depending on the set of accessible nodes, confronted against the output node only. Experiments cover also accuracy comparison between the RBF, MLP and SVM classifiers. Results show advantages and drawbacks of the RBF ANN-based diagnostic module, compared to other available solutions.</span>

Global sliding-mode dynamic surface control for MDF continuous hot-pressing slab thickness via LESO

In this paper, a robust slab thickness tracking control problem is investigated for medium density fiberboard continuous hot-pressing using an electro-hydraulic servo system in the presence of interior parameter perturbations and external load disturbances. By utilizing a linear extended state observer (LESO) and combining dynamic surface control method with a global sliding mode control (GSMC) technique, a robust controller is designed. Firstly, the LESO is constructed to estimate the total number of disturbances for system model compensation. Subsequently, a global sliding-mode dynamic surface controller is designed. Using first order low-pass filters to calculate the derivatives of synthetic control inputs, the controller form is simplified in the procedure. Introducing the GSMC into the third subsystem, the control precision and response speed are further improved. Moreover, an appropriate Lyapunov function is chosen to demonstrate that all signals from the closed-loop system are semi-globally uniformly ultimately bounded and the tracking error converges to zero asymptotically. Finally, numerical simulation results are used to authenticate and validate the benefits of the proposed control scheme.

Extremum Seeking using Synchronous Detection Method with Time-Varying Parameters

The authors suggest an algorithm for extremum seeking based on a random process optimization approach employing a gradient descent method with the synchronous detection technique. The problem consists on finding the minimum of a strongly convex function which is unknown but may be measured in any testing point subject to a noise perturbation. The suggested extremum seeking procedure is based on the estimated gradient obtained by the modified version of the Synchronous Detection Method. We have added a first order low-pass filter to the gradient estimator to attenuate the noise in the estimations. We prove the mean-squared convergence in probability of the suggested algorithm. To validate the contributions of the paper we present a numerical example.

Evaluation of Moving Average Window Technique as Low-pass Filter in Microprocessor-Based Protecting Relays

Over the last decades, with the increase in the use of harmonic source devices, the filtering process has received more attention than ever before. Digital relays operate according to accurate thresholds and precise setting values. In signal flow graphs of relays, the low-pass filter plays a crucial role in pre-filtering and purifying waveforms performance estimating techniques to estimate the expected impedances, currents, voltage etc. The main process is conducted in the CPU through methods such as Man and Morrison, Fourier, Walsh-based techniques, least-square methods etc. To purify waveforms polluted with low-order harmonics, it is necessary to design and embed cutting frequency in a narrow band which would be costly. In this article, a technique is presented which is able to eliminate specified harmonics, noise and DC offset, attenuate whole harmonic order and hand low-pass filtered signals to CPU. The proposed method is evaluated by eight case studies and compared with first and second order low-pass filter.

Twofold Reflectionless Filters of Inverse-Chebyshev Response With Arbitrary Attenuation

A twofold circuit is introduced as a reflectionless filter having inverse-Chebyshev response with arbitrary attenuation in the reject band. The proposed configuration consists of two complementary circuits. A methodology and some equations are described to exactly design a prototype odd order low-pass reflectionless filter. Finally, a filter is built and measured to verify the presented configuration and its design equations.

Clarifying the interplate main tectonic elements of Western Anatolia, Turkey by using GNSS velocities and Bouguer gravity anomalies

In this study, the GNSS and gravity data were processed and compared together for examining the continental structures of the Western Anatolia region which has very complicated tectonism. The GNSS data of three national projects were processed and GNSS velocities were found as approximately 25mm per year towards southwest with respect to the Eurasia fixed frame. In order to investigate the interplate motions of the region, the Anatolian and Aegean block solutions were calculated and the differences in directions and amplitudes of velocities were observed particularly in the Anatolian block solution. Due to the Anatolian block solutions, the study area was grouped into three regions and compared with the tectonic structures as the first time for Western Anatolia by this study. Additionally, W-E and N-S relative GNSS solutions were obtained for observing the possible tectonic borders of the study area. Besides, 2nd order horizontal derivative and low-pass filter methods were applied to Bouguer gravity anomalies and the results of the gravity applications and the changes on crustal-mantle interface were compared with the GNSS horizontal velocities.

Synthesis and Analysis of Electronically Adjustable Fractional-Order Low-Pass Filter

A proposal of a fractional ([Formula: see text])-order low-pass filter is presented in this paper. The proposed filter operates in the current-mode and it is designed using Multi-Output Current Followers (MO-CFs), Dual-Output Current Follower (DO-CF), Dual-Output Adjustable Current Amplifier (DO-ACA) and Adjustable Current Amplifiers (ACAs) as active elements within the presented topology of the filter. The filter possesses ability to electronically control its order and also the pole frequency by changing the current gain of current amplifiers (ACAs) already present in the structure. Three different values of the order and pole frequency of the proposed low-pass filter were tested as an example. Design of the proposed filter is supported by simulation and experimental results. Simulations of the circuit are carried out in PSPICE simulator with behavioral models of used active elements. The experimental laboratory measurements are performed with the help of available devices forming equivalent circuits. Simulations and experimental results of the electronical control of the order and pole frequency are compared in this contribution.

Study on the Frequency Compensation of the Dynamic Unbalance Signal Extraction for General Hard Bearing Dynamic Balancing Machine

When a dynamic balancing measuring system is equipped with velocity sensor as its vibration pick-up, the output signal of the sensor is proportional to the third power of rotating speed of the balancing operation. Generally a third order low-pass filter circuit is often used to eliminate the influence of rotating speed and suppress the high frequency interference as well. However, the frequency response of third order low-pass filter circuit can’t compensate completely for the response characteristic of the vibration system of balancing machine, which then causes measuring error. So, as a general purpose hard bearing dynamic balancing machine being suitable for a wide speed range, frequency compensation must be conducted. The approach of frequency compensation is classified into two broad types: hardware and software compensation. This paper conducts further research on these two methods to improve the accuracy of the measuring system and proves the accuracy and effectiveness of the two methods by signal simulation and field experiments.

Minimum passive components based lossy and lossless inductor simulators employing a new active block

In this paper a new active element namely Dual X current conveyor differential input transconductance amplifier (DXCCDITA) is proposed. The DXCCDITA is utilized in designing eight topologies of lossy and lossless grounded inductor simulators and two topologies of floating inductor simulators. All the designed grounded simulators require only two passive elements and a single active block. The two floating inductor simulators require a single active block and one or three grounded passive elements. In addition, all the designs make use of only grounded capacitors for implementation which is advantageous for fabrication. All the proposed active inductors, except two, did not require any component matching conditions for realization and all the inductor simulators are perfectly tunable. The effect of non-idealities on the proposed grounded simulator structures is also studied. To demonstrate the workability of the inductor simulators they are used in design of second order low pass filter, parallel RLC resonance circuit, third order Butterworth high pass filter, parallel RLC current mode multifunction filter and a voltage mode band pass filter. The DXCCDITA is implemented in 0.35μm TSMC CMOS technology parameters and tested in Tanner EDA. Sufficient number of simulations are provided to establish the functionality of the active inductor structures.

Self-correction of projector nonlinearity in phase-shifting fringe projection profilometry

In phase-shifting fringe projection profilometry, the luminance nonlinearity of the used projector has been recognized as one of the most crucial factors decreasing the measurement accuracy. To solve this problem, this paper presents a self-correcting technique that allows us to suppress the effect of the projector nonlinearity in the absence of any calibration data regarding the projector intensities or regarding the phase errors. In its first step, the standard phase-shifting algorithm is used to recover the phases, as well as the background intensities and the modulations. Using these results enables normalizing the fringe patterns, for ridding them of the effects of the background and modulations. Second, we smooth the calculated phase map by use of a low-pass filter in order to remove the ripple-like phase errors induced by the projector nonlinearity. Third, we determine a polynomial representing the projector nonlinearity by fitting the curve of the normalized fringe intensities against the cosine values of the smoothed phases. Finally, we correct the phase errors using the curve just obtained. Doing these steps in an iterative way eventually results in a phase map and, further, a 3D shape with their artifacts induced by the projector nonlinearity suppressed significantly. Experimental results demonstrate that this technique offers some advantages over others. It does not require a prior calibration of the projector, thus being suitable for dealing with a time-variant nonlinearity; its pointwise operation protects the edges and details of the measurement results from being blurred; and it works well with very few fringe patterns and is efficient in image capturing.

Neural Filter Based Integrator for Virtual Flux Estimation in Direct Power Control of Three-Phase PWM Rectifiers

In this paper, new neural filter (NF) based integrator (NF-I) is developed for virtual flux (VF) estimation in direct power control (DPC) of a three-phase pulse width modulation (PWM) rectifier. The main advantages of the proposed NF-I are its simple structure, accuracy and provides fast VF estimation compared to the traditional first order low-pass (FOLP) filter. The NF capability to online filtering distorted signals is exploited for extracting fundamental components of VF obtained from a pure integration. Numerical simulations of the proposed NF-I inserted in the VF based DPC (VF-DPC) are carried out under different grid voltage conditions. Steady state and dynamic performances of the NF-I are compared with those obtained with the traditional FOLP filter. Simulation results illustrate good performances of the NF-I inserted in the VF-DPC strategy.

Electronically Tunable Fully-Differential Fractional-Order Low-Pass Filter

The paper presents proposal of a fully-differential (1 + α)-order low-pass filter. The order of the filter and its cut-off frequency can be controlled electronically. The filter is proposed using operational transconductance amplifiers (OTAs), adjustable current amplifiers (ACAs) and fully-differential current follower (FD-CF). The circuit structure is based on well-known Inverse Follow-the-Leader Feedback (IFLF) topology. Design correctness of the proposed filter is supported by PSpice simulations with transistor-level simulation models. The ability of the electronic control of the order has been tested for five individual values of parameter α. Furthermore, the ability of the electronic control of the cut-off frequency of the filter has been also tested for five different values. Additionally, the simulation results of the proposed fully-differential (F-D) filter are compared with the results of the single-ended (S-E) equivalent of the presented filter.DOI: http://dx.doi.org/10.5755/j01.eie.23.3.18332

New CMOS realization of high performance Voltage Differencing Inverting Buffered Amplifier and its filter application

This paper describes a high performance voltage differencing inverting buffered amplifier (VDIBA). The transconductance of the proposed circuit is enhanced by using positive feedback technique with only two extra transistors used in active load. Moreover, the bandwidth of proposed circuit is enhanced by using resistive compensation technique. The performance of proposed VDIBA is demonstrated by detailed frequency analysis. Furthermore, it is shown that the transconductance can be enhanced up to 4.61 mS at biasing current of 300 µA. In addition, a third order low pass filter is given as an application example to confirm the high performance of the proposed VDIBA. The proposed low pass filter operates at natural pole frequency of 15 MHz. The proposed VDIBA and its filter application are implemented using TSMC 90 nm CMOS technology in Cadence virtuoso schematic composer at ±0.6 V supply voltage.

Electronically Tunable Fractional Order Filter

In this paper, an electronically tunable resistorless fractional order filter (FOF) based on operational transconductance amplifier (OTA) is presented. It uses two fractional capacitors (FC) of same order and provides fractional order low-pass filter and fractional order band-pass filter responses simultaneously. Mathematical formulations are outlined for various critical frequencies and transfer function sensitivities for presented FOF. The FCs of orders 0.5 and 0.9 are considered for illustrating the proposal. The FCs are realized using the fourth-order continued fraction expansion-based RC ladder and are characterized using SPICE simulations. Functional verification of presented FOF with FC of orders 0.5 and 0.9 is exhibited through SPICE simulations. The OTA is implemented using $$0.5\,\upmu \hbox {m}$$ CMOS technology model parameters. Electronic tunability of half power and right-phase frequencies of presented FOF is achieved through bias current variation of OTA. The transfer functions’ sensitivity with respect to various circuit parameters is also examined through simulations, and it is found that the values remain well within unity for most of the circuit parameters. Furthermore, the presented FOF is attractive from integration viewpoint as it achieves tunability via bias current variation in contrast to tuning through resistor variation in existing FOFs.

Innovative viscoelastic material selection strategy based on dma and mini-shaker tests for spacecraft applications

With the increase of payload sensitivity (such as high precision optics for sub-metric imager), micro-vibration disturbances generated by spinning actuators, if not controlled, may affect on-board instruments and may worsen the quality of pictures taken by an Earth observation imager. For the last two decades, viscoelastic materials have been gradually used in isolators designed for space applications. Their attractiveness comes from their ability to act as a second order low pass filter to minimise micro-vibration forces. In this study, an innovative viscoelastic material pre-selection process has been developed to assess the mechanical and thermal properties of viscoelastic isolators during early design stages. In order to characterise the viscoelastic isolators, tests have been performed at viscoelastic material level (material characterisation) and at viscoelastic isolator level (isolator characterisation). A qualitative correlation has been established between the master curves (material characterisation) and the transmissibility curves (isolator characterisation) which leads to a possible prediction of expected isolation performances of a viscoelastic material during early design stages.

All-inkjet-printed low-pass filters with adjustable cutoff frequency consisting of resistors, inductors and transistors for sensor applications

Low-cost and flexible first and second order low-pass filters with adjustable cutoff frequency were designed and printed by inkjet printing technology. The all-inkjet-printed low-pass filters were characterized and an adjustable cutoff frequency feature in form of an inkjet-printed organic thin-film transistors (OTFTs) was added to the filters for application-oriented fine-tuning. The applicability of these small circuits was evaluated by signal filtering for sensor applications. As a result, low-pass filters with an adjustable cutoff frequency ranging from 82 Hz to 740 Hz were obtained, demonstrating their suitability in signal filtering and their promising applicability for tactile sensing characterized by low frequency signals.

Improving Efficiency of NPP Software Based I&C

The paper considers improving efficiency of NPP software based I&C during adjustment and readjustment of its characteristics. The research analyzes impact of transfer function coefficient of digital components on features of frequency-response characteristics, which shall be considered during design of software based I&C. The paper objective was to determine the numerator and denominator dependencies of transfer function of first order high-pass and low-pass digital filters of cut-off frequency, and also to determine dependencies on pulsation coefficient.