Offset Removal Research Articles

A 1.02-pJ/b 20.83-Gb/s/Wire USR Transceiver Using CNRZ-5 in 16-nm FinFET

An energy-efficient (1.02 pJ/b) and high-speed (20.83 Gb/s/wire, 417 Gb/s/mm) link for ultra-short reach (USR) applications (up to 6-dB channel loss at the Nyquist frequency of 12.5 GHz) is presented. Correlated non-return to zero (CNRZ) signaling with low sensitivity to inter-symbol interference (ISI) has been developed to improve the link budget. In addition to high pin efficiency (5b6w: 5 bits over 6 wires), the proposed signaling method provides very good resistance against common-mode and crosstalk noise sources, allowing for dense routing. A very wide-band (1.3 GHz) jitter tracking mechanism has been employed to reduce the sensitivity of the system to random and deterministic jitter and relax design constraints on transmitter. A slicer with low kick-back noise and a circuit topology well matched to the continuous-time linear equalizer (CTLE) has been designed to provide both high input sensitivity and Process, supply Voltage, and Temperature (PVT) variations tolerance. The link operates with more than 22-ps (42.5% UI) eye opening at BER = 1E-15. Calibration loops are running in background for quadrature mismatch error correction, clock and data alignment (CDA), and offset removal.

Earth\u2019s gravity from space

Satellite gravimetry began with the launch of the satellites Sputnik 1 and 2 in 1957. During the following 43 years, more and more details were discovered and the models of the Earth’s gravity could be refined. Methods improved and more and more satellite orbits and ground stations were added in the analysis, employing more advanced and precise measuring techniques. A new era started with the dedicated gravimetry missions CHAMP (2000–2010), GRACE (2002–2017), and GOCE (2009–2013). The methods of satellite-to-satellite tracking and satellite gradiometry resulted in a substantial improvement of our knowledge of the Earth’s gravity field in terms of accuracy and its spatial and temporal variations. There are three basic ways of using gravity and geoid models in Earth sciences and geodesy. First, in solid Earth physics, the highs and lows of the field are investigated in comparison with an idealized Earth, e.g., a hydrostatic equilibrium figure. In particular, in South America, Africa, Himalaya and Antarctica the gravity field is known much better now, due to GOCE and lead to an improved understanding of the continental crust and lithosphere. Second, in oceanography, the geoid serves as surface in equilibrium, a hypothetical ocean at rest. The ocean topography is the deviation of the actual ocean surface, measured by satellite altimetry, from this reference. The ocean topography serves as a new and independent input to ocean circulation modeling and leads to an improved understanding of ocean transport of mass, heat, and nutrients. Similarly, geodetic heights of the land surface will soon be referred to the geoid, leading to globally consistent heights and enabling the removal of existent systematic deformations and offsets of national and continental height systems. Third, the GRACE time series of monthly gravity models, reflecting seasonal, inter-annual and long-term gravity changes, became one of the most valuable data sources of climate change studies.

Robust 3IMPL Control Algorithm for Power Management of SyRG/PV/BES-Based Distributed Islanded Microgrid

In an islanded ac microgrid, a comprehensive algorithm of a three-phase, improved-magnitude, phase-locked-loop (3IMPL) control algorithm is developed in this paper to provide dc offset removal, steady-state error removal, and fast dynamic response. In addition, the control of the voltage-source converter (VSC) using the 3IMPL algorithm provides voltage and frequency control and elimination of harmonics of nonlinear loads. In the proposed microgrid, a solar photovoltaic (PV) array is connected to the dc link through a boost converter, and an incremental conductance technique is used for extraction of maximum power from a PV array. Due to intermittency of the PV array, a synchronous reluctance generator is used for pico-hydro generation because it is economical, ecologically sustainable, and extremely reliable and requires less maintenance. Moreover, a microgrid suffers from problems of variation in generation and continuous load fluctuations; therefore, for power balancing between the source and the load, a storage battery is connected across the dc link of the VSC through a bidirectional dc-dc converter. Test results on a prototype have verified the control strategy and are able to improve the power quality of the system at varying solar insolation and unbalance in the load.

SOI FinFET based instrumentation amplifier for biomedical applications

In this paper, we present a design of SOI FinFET device based Instrumentation Amplifier (IN-Amp) for biomedical applications. An IN-Amp is operated in weak inversion regime effectively for low power and low voltage applications. The performance metrics of the proposed IN-Amp such as DC gain, Common mode rejection ratio (CMRR) were enhanced by using nanometre FinFET device technology. To achieve these desirable performance metrics, size of transistors is optimized and passive resistances are replaced by active 30 nm SOI FinFET transistor. A FinFET based DC offset removal circuit is designed to reduce the offset voltage at the output of the IN-Amp. The output achieved on appending DC offset removal circuit is exact replica of input over wide range of frequency, which can be adjusted by varying clock inputs to the circuit. It is observed that the proposed SOI FinFET based Instrumentation amplifier achieves an overall gain and CMRR of 99.6 dB and 103 dB respectively.

Validity Study of the Swarm Horizontal Cross‐Track Ion Drift Velocities in the High‐Latitude Ionosphere

AbstractHigh‐latitude ionospheric plasma convection plays a fundamental role in determining many processes in the terrestrial ionosphere. Electric Field Instruments on the European Space Agency's three polar‐orbiting Swarm satellites measure ionospheric ion drift velocities at about 500 km altitude using thermal ion imager energy/angle‐of‐arrival electrostatic analyzers. Recently, European Space Agency released horizontal cross‐track components of these drifts, calibrated at high latitudes. This paper concerns the validation of the Swarm horizontal cross‐track ion drift measurements. All available Swarm‐A and Swarm‐B 2 Hz data between November 2015 and July 2017 were used and the climatology of high‐latitude ion convection was constructed and examined. Results were compared to corresponding climatology obtained from the Weimer 2005 empirical convection electric field model under different interplanetary magnetic field and solar wind conditions in the northern and southern hemispheres, separately. The ion drift data sometimes exhibit large offsets at middle latitudes. However, following a recalibration of the drifts using a refinement of the offset removal, the Swarm cross‐track ion drift climatology agrees reasonably well statistically with the Weimer 2005 model, and properly responds to the changing geospace environment. The two results agree within about 200 m/s (root‐mean‐square deviation), however the correlations are higher for southward interplanetary magnetic field and in the northern hemisphere (rswarm‐A = 0.84, rswarm‐B = 0.77), for which the corresponding magnitudes of Swarm‐A and Swarm‐B drifts are ~14% and ~33% larger than the model estimates, respectively. The convection patterns seen in the revised Swarm horizontal cross‐track drift velocities are more structured than those obtained using the model, but overall no significant systematic errors are present.

DC Offset Removal Algorithm for Improving Location Estimates of Momentary Faults

Fault location algorithms require the input of voltage and current phasors when estimating the distance to a fault. In the case of momentary faults, phasor calculations are often complicated by the presence of an exponentially decaying dc offset. Fourier filters and cosine filters, popularly used by most phasor estimation algorithms in relays, are successful in filtering out most, but not all, of the exponentially decaying dc offset. This dc offset affects the accuracy of voltage and current phasors and may result in a significant error in location estimates. Therefore, this paper presents a dc offset removal algorithm to improve the fault location estimates of momentary faults. The algorithm uses the rms-wavelet method for fault detection and estimates voltage and current phasors using non-linear least squares methods. The proposed method uses variable window size in calculating phasors and estimates a single, but more accurate fault location than multiple locations estimated by the Fourier and cosine filters. The method is validated using simulated and actual field data. The location estimates are shown to be accurate within 5.6% in all cases.

Adaptive Low-Pass Filter Based DC Offset Removal Technique for Three-Phase PLLs

The presence of dc offset in the inputs of a phase-locked loop (PLL) introduces fundamental frequency oscillations in the estimated quantities. Due to their low frequency in a synchronous reference frame, removal of these oscillations is a challenging task. Recent design studies of pre/in-loop filtering based advanced PLLs show that incorporation of dc offset removal in a filtering stage reduces the bandwidth of the PLL. This degrades the dynamic performance of the PLL and results in slower response time. To tackle this issue, a simple yet effective dc offset removal technique based on adaptive low-pass filters is introduced in this letter. The proposed technique can be applied as an add-on to any PLL structures without altering their design. Therefore, its application has a minimal effect on the dynamic performance of the PLL under study. The effectiveness of the proposed technique is evaluated experimentally by applying it to different PLL structures.

AlGaN/GaN Micro-Hall Effect Devices for Simultaneous Current and Temperature Measurements From Line Currents

GaN/Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.20</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.80</sub> N/GaN heterostructures were grown by molecular beam epitaxy and fabricated into micro-Hall effect sensors for the purpose of simultaneous current and temperature detection. The devices were characterized over a temperature range of -183 °C to 252 °C and were determined to be linearly dependent on magnetic field and temperature throughout. The high room temperature mobility of 2000 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs allowed for a very high magnetic field sensitivity of 113 VA <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> T <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , which only decreased to 80 VA <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> T <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> at 252 °C. The ability to measure temperature while at the same time measure the magnitude of the B-field, and thus current in a nearby line is demonstrated. A method of decoupling temperature and current signatures is also shown together with a simple method of offset voltage understanding and removal.

A DC offset removal algorithm based on AR model

ABSTRACTThis work proposes an auto-regressive (AR) model-based algorithm that can eliminate the adverse influence of the exponentially decaying DC offset in the phasor estimation process using discrete Fourier transform (DFT). The proposed algorithm comprises three stages: DFT, AR model implementation, and compensation. First, DFT can eliminate all harmonic components and estimate the phasor of the fundamental frequency component. Second, the AR model is used to calculate the error caused by the exponentially decaying DC offset in the phasor value estimated by DFT. A second-order AR model that uses three successively estimated phasor values is utilized. Finally, the phasor of the fundamental frequency component can be accurately estimated by compensating the error caused by the exponentially decaying DC offset. The performance of the proposed algorithm is evaluated for a-phase to ground fault on a 154 kV 25 km overhead transmission line. Electromagnetic Transients Program is used to generate fault signals...

DVCC-based very low-offset current-mode instrumentation amplifier

ABSTRACTThis paper presents an alternative implementation of a chopper-modulated current-mode instrumentation amplifier. The structure provides very low-offset voltage at the output due to chopper modulation and residual offset removal path. The residual offset removal path is based on low-pass filtering using grounded capacitances which provides compact design structure compared to various chopper-modulated instrumentation amplifier designs. Rail-to-rail input common-mode range is possible due to transmission gate-based input chopper switching scheme. The design is made using a 0.35-µm CMOS process with ±1.65 V supply voltage. The area of the amplifier is 234µm × 344 µm, including all the filtering elements. The proposed circuit with residual offset removal path provides less than 1 µV input referred offset voltage. The advantage of the proposed instrumentation amplifier is its large bandwidth, simple design scheme and compact area compared to chopper-modulated voltage mode amplifiers.

Power efficiency, phase noise, and DC offset in constant envelope OFDM transceivers

AbstractThis paper considers constant envelope orthogonal frequency‐division multiplexing (CE‐OFDM) that is an attractive candidate for the future Long Term Evolution over satellite and device‐to‐device communications in merging public safety and commercial networks. The constant envelope modulation allows power amplifier (PA) to operate near saturation levels thus maximizing power efficiency. Because the phase noise transforms just into an additive noise term after the phase detector, the CE‐OFDM has significant advantage compared with phase noise sensitive OFDM. The transceiver power efficiency is evaluated by measuring the bit error rate as a function of average PA input signal‐to‐noise ratio so that the effects of the PA nonlinearities are taken into account in the performance evaluation. Our simulation results show that with a typical nonlinear satellite amplifier, the CE‐OFDM has up to 6.0dB gain compared with the OFDM. This is beneficial especially in a channel having high attenuation. The consistent gains for the ideally linearized amplifier and common terrestrial three‐way Doherty amplifiers are 2.2 and 2.5dB, respectively. The enhanced PA efficiency enables battery to be smaller or last longer in mobiles devices. For CE‐OFDM implementation, a simple transmitter and receiver structure with novel direct current offset removal is presented by keeping in mind that the key factor for the rapid uptake of the future fifth generation systems is the maximization of technology commonalities with existing systems. Copyright © 2016 John Wiley &amp; Sons, Ltd.

전기철도 AT급전계통에 Low-Pass Filter를 이용한 직류옵셋 제거에 관한 연구

전기철도 AT급전계통에 Low-Pass Filter를 이용한 직류옵셋 제거에 관한 연구

Accurate and fast DC offset removal method for digital relaying schemes

In digital protection systems, discrete Fourier transform (DFT) technique is the most widely used frequency analysis tool for extraction of fundamental and harmonic components of fault currents. However, some fault currents are accompanied by decaying direct current (DC) offset which affects the accuracy of the DFT-based methods as the polluted fault current with decaying DC offset is not a periodic signal. This matter may cause mal-operation of some protection schemes such as overcurrent and distance relays. In this study, to address this issue and decrease the estimation error, a novel technique is proposed to eliminate the effects of DC offset on DFT-based methods. In the proposed method, the decaying DC offset is estimated using one-cycle data windows of the fault current signal. By subtracting the estimated decaying DC offset from the fault current, the remaining signal becomes periodic. Thereafter, the DFT method can be effectively used for extraction of fundamental and other harmonic components. The performance of the proposed method is evaluated comprehensively by investigating different signals even in noisy conditions. Also, a prototype is conducted to validate the applicability of the proposed method in the real power system by real-time simulation.

양전원 송전선로의 고장점 표정 알고리즘

In order to service restoration and enhance power system reliability, a number of impedance based fault location algorithms have been developed for fault locating in a transmission line. This paper presents an advanced impedance-based fault location algorithms in a two-ended sources transmission line to reduce the DC offset error effects. This fault location algorithm uses of the GPS time synchronized voltage and current signals from the local and remote terminal. The algorithm uses an advanced DC offset removal filter. A series of test results using ATPdraw simulation data show the performance effectiveness of the proposed algorithm. The proposed algorithm is valid for a two-end sources transmission network.

송전선로용 디지털 고장점 표정장치에 관한 연구

Transmission line is exposed to a large area, and then faults are likely to occur than the other component of power system. When a fault occurs on a transmission line, fault locator helps fast recovery of power supply on power system. This paper deals with the design of a digital fault locator for improvement accuracy of the fault distance estimation and a fault occurrence position for transmission line. The algorithm of a fault locator uses a DC offset removal filter and DFT filter. The algorithm utilizes a fault data of GPS time synchronized. The computed fault information is transmitted to the other side substation through communication. The digital fault locator includes MPU module, ADPU module, SIU module, and a power module. The MMI firmware and software of the fault locator was implemented.

Exponentially decaying DC offset removal for phasor measurement using second‐order differential

This letter proposes an exponentially decaying DC offset removal scheme for phasor measurement in power systems. Considering the features of the parameters of the transmission lines (i.e., the reactance X is much larger than the resistance R of a transmission line), the second‐order differential of a faulted current signal can be utilized to suppress the DC offset to a great degree. Then the full‐cycle Fourier algorithm (FFA) is employed to calculate the phasors of the periodic components correctly. Simulation studies demonstrate that the proposed scheme can remove the DC offset to a great degree, leading to higher accuracy and faster convergence in phasor calculation than FFA. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.

COMPARATIVE MORPHOLOGY OF SOLAR RELATIVISTIC PARTICLE EVENTS

Time profiles of the 0.25–10 MeV electrons and the ~(0.1–1) GeV nucleon−1 protons and helium associated with two solar coronal mass ejections (CMEs) are analyzed with a newly formulated method based on modeling of the particle transport in the interplanetary medium. With the modeling, we fit the observed angular distribution of solar particles and infer, for a particular particle instrument and magnetic field orientation, the time delay of the particle registration at 1 AU in respect to the solar source. Then, after the time offset removal, intensity re-normalization and background equalization, the time–intensity profiles of high-energy protons, helium and electrons in different energy channels are superposed and compared. The comparison reveals episodes of remarkable coincidence of different profiles, as well as episodes of essentially different behavior. It implies at least three sources of solar high-energy particles operating in a single event. The first, short-duration source emits electrons next to the flare's impulsive phase and CME liftoff. The second source gradually rises and continues for more than an hour, emitting electrons and lower energy protons, which is consistent with shock acceleration on open magnetic field lines extending to solar wind. An another, third source is the main source of relativistic ions in space. It is retarded in respect to the flare's impulsive phase and may be associated with a structure encountered by the shock within a few solar radii from the Sun.

병행 2회선 송전선로의 개선된 거리계전기법

This paper proposes an advanced distance relaying based on the DC offset removal filter to minimize the effects of DC offset on a double circuit transmission line. The proposed DC offset removal filter uses only one cycle of data for phasor extraction computation, which does not need to preset the time constant of the DC offset component. This proposed distance relaying uses not only the residual current of the faulted circuit but also mutual current of the healthy adjacent circuit. A series of off-line test results using ATP simulation data show the effectiveness of the an advanced distance relaying.

宅内同軸網におけるフィルタバンクマルチキャリヤ伝送とDCオフセット妨害軽減法を用いた地上デジタルテレビ放送共存大容量分配伝送

宅内同軸網におけるフィルタバンクマルチキャリヤ伝送とDCオフセット妨害軽減法を用いた地上デジタルテレビ放送共存大容量分配伝送

고차 구성의 개선된 직류 옵셋 제거 필터

Fault currents are expressed as a combination of harmonic components and exponentially decaying DC offset components, during the occurrence of fault in power system. The DC offset components are included, when the voltage phase angle of fault inception is closer to or . The digital protection relay should be detected quickly and accurately during the faults, despite of the distortions of relaying signal by these components. It is very important to implement the robust protection algorithm, that is not affected by DC offset and harmonic components, because most relaying algorithms extract the fundamental frequency component from distorted relaying signal. So, In order to high performance in relaying, advanced DC offset removal filter is required. In this paper, a new DC offset removal filter, which is no need to preset a time constant of power system and accurately estimate the DC offset components with one cycle of data, is proposed, and compared with the other filter. In order to verify performance of the filter, we used collecting the current signals after synchronous machine modeling by ATPDraw5.7p4 software. The results of simulation, the proposed DC offset removal filter do not need any prior information, the phase delay and gain error were not occurred.