Passive Loop Research Articles

Chip design of a 5.8-GHz fractional-N frequency synthesizer with a tunable Gm−C loop filter

This paper proposes a novel Gm−C loop filter instead of a conventional passive loop filter used in a phase-locked loop. The innovative advantage of the proposed architecture is tunable loop filter bandwidth and hence the process variations of passive elements of resistance R and capacitance C can be overcome and the chip area is greatly reduced. Furthermore, the MASH 1-1-1 sigma-delta (ΣΔ) modulator is adopted for performing the fractional division number and hence improves the phase noise as well. Measured results show that the locked phase noise is −114.1 dBc/Hz with lower Gm−C bandwidth and −111.7 dBm/C with higher Gm−C bandwidth at 1 MHz offset from carrier of 5.68 GHz. Including pads and built-in Gm−C filter, the chip area of the proposed frequency synthesizer is 1.06 mm2. The output power is −8.69 dBm at 5.68 GHz and consumes 56 mW with an off-chip buffer from 1.8-V supply voltage.

R&D on passive stabilization loop at EAST

The passive stabilization loop (PSL) is part of the plasma stabilization system built in the EAST. Its purpose is to provide passive feedback control of the plasma vertical instability on short time scales. To accommodate with the new stage for high performance plasma and enhance the control of vertical stabilization in EAST, the project of PSL has been carried out. The eddy currents are induced by the vertical displacement events (VDEs) and disruption. The distribution of the eddy currents depend on the structure of the PSL and the formation of the induction. The global model is created and meshed by the ANSYS software. Based on the simulation of plasma VDEs and disruption, the distribution and decay curve of the eddy currents on the PSL are obtained. The stress and the strain caused by the eddy currents and the magnetic field are calculated. To decrease the resistance of the joint and enhance anti-corrosion of the joint surface, the silvered craft is used. In the experiment of test model, the resistance is decreased to half after silvered with the same matrix material and under the same preload. The PSL is insulated from the vacuum vessel at the supports of passive stabilizers. The insulation structure is designed and tested with ceramic material. The PSL is designed, fabricated and assembled with the total resistance 150μΩ. It can supply passive feedback control to the plasma by the eddy currents induced by the VDEs, which could enhance the vertical placement control of plasma.

Magnetic field mitigation by means of passive loop: technical optimization

PurposeThe purpose of this paper is to present an approach to design passive loop systems in order to reach good performances.Design/methodology/approachThe optimization has been performed by means of the MATLAB optimization toolbox “Gatool” which solves the optimization problems with a genetic algorithm.FindingsSeveral configurations have been analyzed by varying the number of loops from 2 to 15, whose geometry has been chosen by the genetic algorithm. Considering a five loops configuration, along the reference path it is possible to obtain a shielding factor almost constant and equal to 3.5.Originality/valueThe optimized configurations have been compared with a practical employed layout composed of 17 closed loops placed above and around the junction zone. The shielding factors obtained by the six loops configuration are comparable with the ones of the practical layout.

Magnetic shielding solutions for the junction zone of high voltage underground power lines

In this paper a comparison among different shielding techniques for the junction zone of high voltage underground power lines is presented. Three technologies are taken into account: flat conductive shield, passive loop and High Magnetic Coupling Passive Loop. The three solutions are simulated using 2D and 3D models in order to evaluate the magnetic flux density at ground level, the shielding factor and the effectiveness of connection between components of the shield. Shielding performances and installation requirements have been compared by highlighting advantages and drawbacks of the three systems and identifying the most suitable solution with reference to the Italian regulatory framework.

A Novel Fiber-Based Variable All-Optical Packet Buffer Based on Self-Phase-Modulation-Induced Spectral Broadening

We propose a novel optical delay control mechanism to realize variable all-optical packet buffering, in which the amount of optical delay is controlled by the input signal power level. It consists of a passive fiber delay loop followed by an optical power dependent filter, which is realized by means of two stages of self-phase-modulation-induced spectral broadening and offset filtering. The feasibility of the proposed optical packet buffer has been investigated through numerical simulations and experiments. No polarization control and additional laser source are needed.

Zero-lag synchronization and bubbling in delay-coupled lasers

We show experimentally that two semiconductor lasers mutually coupled via a passive relay fiber loop exhibit chaos synchronization at zero lag, and study how this synchronized regime is lost as the lasers' pump currents are increased. We characterize the synchronization properties of the system with high temporal resolution in two different chaotic regimes, namely, low-frequency fluctuations and coherence collapse, identifying significant differences between them. In particular, a marked decrease in synchronization quality develops as the lasers enter the coherence collapse regime. Our high-resolution measurements allow us to establish that synchronization loss is associated with bubbling events, the frequency of which increases with increasing pump current.

A Reconfigurable Passive UHF Reader Loop Antenna for Near-Field and Far-Field RFID Applications

This letter presents a passive UHF printed loop antenna with left-handed loading. The RFID reader antenna can work at near- and far-field operation within the European UHF (865-868 MHz) band. The operation frequency and radiation properties can be modified by employing varactor diodes. Also, the antenna can work in the near-field region having a flat magnetic distribution in the interrogation zone. A comparative study with other passive RFID reader conventional antennas shows that the left-handed loop achieves stronger near H-field with good impedance matching. Design details, simulated results, and a fabricated prototype are presented. The concept significantly extends the design degrees of freedom for RFID antennas.

Resonant enhancement of a passive coil-capacitance loop in eddy current sensing path

A passive resonant coupling loop was composed by connecting an inductive coil with a capacitance element in series. Without any electric connection with measurement circuits, the loop is coaxially inserted into the sensing path between the sensing coil and metallic target of an eddy current proximity sensor. When the sensor is working around the natural frequency of the resonant loop, the mutual coupling between the sensing coil and metallic target is efficiently improved. Home-made eddy current proximity sensing coils are experimentally tested in frequencies around 800kHz. The results indicate that the equivalent inductance of the sensing coil performs more sensitively to metallic target distance. Thus the higher sensitivity and resolution of proximity sensor will be expected.

The high magnetic coupling passive loop: A steady-state and transient analysis of the thermal behavior

Abstract This paper deals with a new concept of technology for the mitigation of the magnetic field produced by underground power lines called “High Magnetic Coupling Passive Loop” (HMCPL). The working principle of this technique is the creation of a current with the same amplitude but opposite phase for each source conductor, in order to nullify the magnetic field in a specified region. Since the number of thermal sources in the shielding region is roughy doubled, the aim of the paper is the investigation of the thermal behavior of HMCPL directly buried in the ground, both in transient and in steady-state conditions. The study is carried out with simulations in order to verify any possible configurations of the shield. Results confirm that HMCPL is a safe technology which does not modify the thermal behavior of the power line.

Power Frequency Magnetic Field Reduction Method for Residents in the Vicinity of Overhead Transmission Lines Using Passive Loop

A power frequency magnetic field reduction method using passive loop is presented. This method can be used to reduce magnetic fields generated within the restricted area near transmission lines by alternating current overhead transmission lines. A reduction algorithm is described and related equations for magnetic field reduction are explained. The proposed power frequency magnetic field reduction method is applied to a scaled-down transmission line model. The lateral distribution of reduction ratio between magnetic fields before and after passive loop installation is calculated to evaluate magnetic field reduction effects. Calculated results show that the passive loop can be used to cost-effectively reduce power frequency magnetic fields in the vicinity of transmission lines generated by overhead transmission lines, compared with other reduction methods, such as active loop, increase in transmission line height, and power transmission using underground cables.

A Low Power Frequency Synthesizer for 60-GHz Wireless Personal Area Networks

In this brief, a 60-GHz frequency synthesizer for wireless personal area networks is designed using 0.13- μm CMOS technology. The synthesizer operates at 60 GHz with phase noises of -98, -117, and -128 dBc/Hz at 1-, 10-, and 40-MHz frequency offsets, respectively. The 60-GHz clock is generated by combining a phase-locked loop (PLL) and an injection-locked oscillator. The PLL provides frequency tuning of the 60-GHz voltage-controlled oscillator (VCO) using replica tuning. A pulse train is generated using a novel passive delay-locked loop and a CMOS pulse generator. This pulse train is then used for filtering the phase noise of 60-GHz VCO up to a high offset frequency. The total power consumption of the frequency synthesizer is 57 mW with a 1.2-V power supply.

A Novel Technology for Magnetic-Field Mitigation: High Magnetic Coupling Passive Loop

In this paper, a new concept of passive-loop technique called the “high magnetic coupling passive loop” is presented. The proposed shielding technique is characterized by high performances and takes all of the advantages of passive and active shields. The shielding technique can be adopted in different application fields: power lines, line transformer connections, etc. In this paper, the proposed shielding is deeply analyzed. The working principle will be explained and validated by means of simulations and laboratory measurements on some prototypes. Finally, the actual performances of the shield installed on a high-voltage power line are presented, discussed, and compared with the result obtained by means of classical passive loops.

A Passive Third-Order Cascade PLL Filter

In this paper, the traditional passive loop filter is improved, and a new type of Cascade Third-order filter structure and Graphical Phase Design method is proposed, which greatly simplifies high-order PLL filter’s design, analysis and calculation. According to graphical phase design principle, parameters for cascade third-order filter could be figured out from the given formula, the derived result is simulated in the form of Bode plots and Unit-step response with Pspice software and the loop target under different parameters is compared. Experiments show that this third-order filter could significantly improve the stability of PLL, deeply attenuate the phase detector’s high-frequency noise and is well adapted to the loop gain change. Users can also change the design parameters flexibly according to the system requirements with this filter.

ICONE19-43763 DESIGN AND TRANSIENT ANALYSES OF PASSIVE EMERGENCY FEEDWATER SYSTEM OF CPR1000 : PART I: AIR COOLING CONDITION

The steam generator secondary passive emergency feedwater system is a new design for traditional generation II+reactor CPR1000. The passive emergency feedwater system is designed to supply water to the SG shell side and improve the safety and reliability of CPR1000 by completely or partially replacing traditional emergency water cooling system in the event of the feed line break (FLB) or loss of heat sink accident. The passive emergency feedwater system consists of steam generator (SG), heat exchanger (HX), air cooling tower, emergency makeup tank (EMT), and corresponding pipes and valves for air cooling condition. In order to improve the safety and reliability of CPR1000, the model of the primary loop system and the passive emergency feedwater system was developed to investigate residual heat removal capability of the passive emergency feedwater system and the transient characteristics of the primary loop system affected by the passive emergency feedwater system using RELAP5/MOD3.4. The transient characteristics of the primary loop system and the passive emergency feedwater system were calculated in the event of feed line break accident. Sensitivity studies of the passive emergency feedwater system were also conducted to investigate the response of the primary loop and the passive emergency feedwater system on the main parameters of the passive emergency feedwater system. The passive emergency feedwater system could supply water to the SG shell side from the EMT successfully. The calculation results showed that the passive emergency feedwater system could take away the decay heat from the primary loop effectively for air cooling condition, and that the single-phase and two-phase natural circulations were established in the primary loop and passive emergency feedwater system loop, respectively.

Loop Enhanced Passive Source- and Load-Pull Technique for High Reflection Factor Synthesis

An original source- and load-pull topology based on a passive technique is presented in this paper. The proposed system consists of passive tuners and loop structures. The use of a passive loop structure in cascade with a passive tuner allows for synthesis of reflection coefficients in the order of 0.97 magnitudes at the device under test's access plane. The measurement and characterization results of a 1W GaAs MESFET device show an improvement of 0.9 dB in the gain and 6% in the power-added efficiency when the proposed impedance synthesis techniques are used.

A 9‐mW Continuous‐time Hybrid Active–Passive ΣΔ Modulator with 84‐dB Dynamic Range

AbstractA hybrid active–passive, continuous time (CT) sigma–delta (ΣΔ) modulator with a multibit quantizer is presented. The modulator is designed as a fifth‐order, dual‐loop architecture, allowing for a maximum quantizer delay of half a clock period. By removing the summing block before the quantizer as well as by introducing an active–passive hybrid loop filter, the design achieves high signal‐to‐noise ratio (SNR) comparable to a fourth‐order active design while dissipating power equivalent to a third‐order implementation. A data‐weighted averaging (DWA) algorithm implemented with analog reference shuffling is utilized to suppress the mismatches in the current‐steering digital‐to‐analog conversion (DAC) with no extra delay introduced between the quantizer and DAC. The chip, manufactured in a 1.8‐V, 0.18‐µm complementary metal oxide semiconductor (CMOS) process, experimentally achieves 79.5 dB peak SNR, 78 dB peak signal‐to‐noise‐and‐distortion ratio (SNDR), and 84‐dB dynamic range over a 1‐MHz signal bandwidth. The 0.43‐mm2 test chip consumes 9‐mW of power when clocked at 128 MHz. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Viable Fibroblast Matrix Patch Induces Angiogenesis and Increases Myocardial Blood Flow in Heart Failure After Myocardial Infarction

This study examines a viable biodegradable three-dimensional fibroblast construct (3DFC) in a model of chronic heart failure. The viable fibroblasts, cultured on a vicryl mesh, secrete growth factors that stimulate angiogenesis. We ligated the left coronary artery of male Sprague-Dawley rats, implanted the 3DFC 3 weeks after myocardial infarction and obtained end point data 3 weeks later, that is, 6 weeks after myocardial infarction. Implanting the 3DFC increases (p<0.05) myocardial blood flow twofold, microvessel formation (0.02±0.01 vs. 0.07±0.03 vessels/μm2), and ventricular wall thickness (0.53±0.02 to 1.02±0.17mm). The 3DFC shifts the passive pressure volume loop toward the pressure axis but does not alter left ventricular (LV) ejection fraction, systolic displacement, LV end-diastolic pressure/dimension, or LV cavity area. The 3DFC stimulates selected cytokine activation with a decrease in the proinflammatory cascade and increased total protein content stimulated by strained 3DFC in vitro. The 3DFC functions as a cell delivery device providing matrix support for resident cell survival and integration into the heart. The imbedded fibroblasts of the 3DFC release a complex blend of cardioactive cytokines promoting increases in microvessel density and anterior wall blood flow but does not improve ejection fraction or alter LV remodeling.

A liquid parahydrogen target for the measurement of a parity-violating gamma asymmetry in [formula omitted

A 16 l liquid parahydrogen target has been developed for a measurement of the parity-violating γ -asymmetry in the capture of polarized cold neutrons on protons in the n ⇒ + p → d + γ reaction by the NPDGamma collaboration. The target system was carefully designed to meet the stringent requirements on systematic effects for the experiment and also to satisfy hydrogen safety requirements. The target was designed to preserve the neutron polarization during neutron scattering on liquid hydrogen (LH 2), optimize the statistical sensitivity to the n ⇒ + p → d + γ reaction, minimize backgrounds coming from neutron interaction with the beam windows of the target cryostat, minimize LH 2 density fluctuations which can introduce extra noise in the gamma asymmetry signal, and control systematic effects. The target incorporates two mechanical refrigerators, two ortho–para convertors, an aluminum cryostat, an aluminum target vessel shielded with 6Li-rich plastic, a hydrogen fill/vent line with a passive recirculation loop to establish and maintain the equilibrium ortho–para ratio, a hydrogen relief system coupled to a vent stack, a gas handling system, and an alarm and interlock system. Low Z, nonmagnetic materials were used for the target vessel and cryostat. Pressure and temperature sensors monitored the thermodynamic state of the target. Relative neutron transmission measurements were used to monitor the parahydrogen fraction of the target. The target was thoroughly tested and successfully operated during the first phase of the NPDGamma experiment conducted at the FP12 beam line at Los Alamos Neutron Science Center (LANSCE). An upgraded version of the target system will be used in the next stage of the experiment, which will be performed at the Fundamental Neutron Physics Beam (FnPB) line of the Spallation Neutron Source at Oak Ridge National Laboratory.

An optoelectronic probe with loss compensation for electromagnetic monitoring at low frequencies

We explore the development of an optoelectronic probe for MF/HF/VHF (up to ∼ 37 MHz) radio frequency bands able to display the complete waveforms. It was built from simple, low cost and robust components. A passive loop antenna generates RF current which modulates an ultra-bright LED of display/illumination. The light signals are transmitted along a PMMA plastic optical fibre (POF) to an optical receiver placed in a remote site. All characterization measurements were carried out in the near-field region. Far-field radio transmissions could also be detected. The probe presented at 0.5 MHz tuning-band has shown a 62 dBµV dynamic range and was able to detect down to Hmin ∼ 0.8 nA cm−1 magnetic field amplitude. A new technique for loss compensation of the fibre link is proposed and successfully tested.

Optimal design of “high magnetic coupling passive loop” for power lines field mitigation

PurposeThe purpose of this paper is to present a new concept of passive loop technique called “high magnetic coupling passive loop” (HMCPL) (suitable for buried power lines) along with optimised design parameters.Design/methodology/approachThe optimal design (geometrical displacement and shielding current intensity and phase) for the mitigation of magnetic field produced by flat and trefoil configuration of the power line is carried out by means of genetic algorithm.FindingsDifferent layouts for the source (flat and trefoil configuration) and the shield (introduction of the phase splitting technique) are designed. The optimization parameters are the coordinates of the shield conductors and the transformer ratio of the magnetic core that couple the source and the shield. Moreover, physical constraints as maximum depth of excavation and geometric interference between cables were introduced in the optimization procedure.Originality/valueThe paper deals with a very new technology for field mitigation called HMCPL. Actually, the base layout of the HMCPL does not need an optimal design. On the other hand, in some applications the base layout cannot be used, therefore, the introduction of an optimal design cannot be avoided. In this paper, the optimal design of several configurations is performed showing that the performances of the HMCPL are very interesting even if the base layout cannot be used.