Electromagnetic Interference Immunity Research Articles

A 16.1-bit Resolution 0.064-mm2 Compact Highly Digital Closed-Loop Single-VCO-Based 1-1 Sturdy-MASH Resistance-to-Digital Converter With High Robustness in 180-nm CMOS

A novel direct resistive-sensor-to-digital readout circuit is presented, which achieves 16.1-bit ENOB while being very compact and robust. The highly digital time-based architecture employs a single voltage-controlled oscillator (VCO), counter, and digital feedback loop for the readout of an external single-ended highly nonlinear resistive sensor, such as an NTC thermistor. In addition to the inherent first-order noise shaping due to the oscillator, the second loop in SMASH configuration creates second-order noise shaping. Fabricated in 180-nm CMOS, the readout circuit achieves 16.1 bit of resolution for 1-ms conversion time and consumes only $171~\mu \text{W}$ , resulting in an excellent 2.4-pJ/c.s. FOMW for a resistive sensor interface while occupying only 0.064 mm 2. The specific closed-loop architecture tackles the VCO nonlinearity, achieving more than 14 bits of linearity. Multiple prototype chip samples have been measured in a temperature-controlled environment from −40 °C to 125 °C for the readout of commercial external NTC thermistors. A maximum temperature inaccuracy of 0.3 °C is achieved with only one-point trimming at room temperature. Since the circuit architecture decouples the sensor excitation from the feedback, high electromagnetic interference (EMI) immunity at the sensor node is demonstrated as well.

Suppression of reverberations at fiber tips for optical ultrasound sensing

Fabry-Perot-based ultrasound sensors at fiber tips have performed high sensitivity and immunity of electromagnetic interference with a relatively compact size. Nevertheless, the reverberation at fiber tips causes a strong noise that degrades the sensing capability. Here we propose a fiber optical-based ultrasound sensor with three design approaches to reduce the reverberation, including designs with an eccentric core, absorptive shield, and arc edge. The effect was experimentally validated with a photoacoustic signal excitation. Compared with bare single-mode fibers in simulation, the low-reverberation design increased the signal-to-noise ratio by 32.1 dB with identical excitation. The experimental results demonstrated the "clean" response with almost invisible reverberations, which was validated by a commercial hydrophone. This research solved the reverberation problems and provided a low-noise design for fiber optic ultrasound sensing.

Microwave Photonics for Remote Sensing: From Basic Concepts to High-Level Functionalities

In the last decades, photonic technologies have been increasingly proposed for microwave and millimeter-wave applications, opening the way to the development of a new field of research known as Microwave Photonics. The hybridization of the microwave world with photonics has demonstrated a beneficial impact on both communications and remote sensing. 5G radio access networks, as well as the next-coming generation of distributed, multistatic radars, are expected to massively leverage on photonic techniques for the generation, distribution, processing, and acquisition of microwave signals. This is due to the advantages brought about by photonics in terms of system transparency to the employed frequency or waveform, low losses, electromagnetic interference immunity, high signal stability. In particular, the inherent coherence guaranteed by photonics will enable next-future multiple input-multiple output radars with enhanced performance. In this paper, we expose in detail some of the most widely employed functions on RF signals obtained with photonic techniques, highlighting the achievable performance that help overcoming some limitations of classical electronic technologies. Finally, two recently implemented microwave photonics systems are described, i.e., a multiple input-multiple output radar and a RF spectrum scanner, showing with practical examples all the potential of microwave photonics systems.

Metamaterial waveguides as integrated optics sensor

We study sensors based on metamaterial cladded waveguides for monitoring gas or liquid specimens. These multilayer structures are made of metal and dielectric thin film claddings, surrounding a hollow core. Mechanical strength, electromagnetic interference immunity, compact layout and connection reliability, make them appropriate to indoor or open air sensing system applications. Sensitivity to sample dielectric constant optical response is numerically calculated and analyzed in different metamaterial sensor designs.

GaN 2DEG Varactor-Based Impulse Suppression Module for Protection Against Malicious Electromagnetic Interference

A GaN-based metal–semiconductor–metal varactor with a two-dimensional electron gas (2DEG) layer is proposed and fabricated. The capacitance variation of this fabricated varactor biased at different external voltages is studied and measured, and the frequency-dependent capacitance and resistance of the varactor are simulated by a corresponding empirical formula. A high-frequency protective filter is further constructed and placed under a large pulsed-current injection in a malicious electromagnetic interference immunity test. The results show that the proposed GaN-based module can reduce the large pulsed current to an acceptably small level. Thus, the GaN-based 2DEG varactor is an attractive candidate for applications designed to protect the upcoming 5G high-frequency system from risks such as electrostatic discharge, lightning, and electromagnetic pulses.

A Comprehensive Survey on “Various Decoupling Mechanisms With Focus on Metamaterial and Metasurface Principles Applicable to SAR and MIMO Antenna Systems”

Nowadays synthetic aperture radar (SAR) and multiple-input-multiple-output (MIMO) antenna systems with the capability to radiate waves in more than one pattern and polarization are playing a key role in modern telecommunication and radar systems. This is possible with the use of antenna arrays as they offer advantages of high gain and beamforming capability, which can be utilized for controlling radiation pattern for electromagnetic (EM) interference immunity in wireless systems. However, with the growing demand for compact array antennas, the physical footprint of the arrays needs to be smaller and the consequent of this is severe degradation in the performance of the array resulting from strong mutual-coupling and crosstalk effects between adjacent radiating elements. This review presents a detailed systematic and theoretical study of various mutual-coupling suppression (decoupling) techniques with a strong focus on metamaterial (MTM) and metasurface (MTS) approaches. While the performance of systems employing antenna arrays can be enhanced by calibrating out the interferences digitally, however it is more efficient to apply decoupling techniques at the antenna itself. Previously various simple and cost-effective approaches have been demonstrated to effectively suppress unwanted mutual-coupling in arrays. Such techniques include the use of defected ground structure (DGS), parasitic or slot element, dielectric resonator antenna (DRA), complementary split-ring resonators (CSRR), decoupling networks, P.I.N or varactor diodes, electromagnetic bandgap (EBG) structures, etc. In this review, it is shown that the mutual-coupling reduction methods inspired By MTM and MTS concepts can provide a higher level of isolation between neighbouring radiating elements using easily realizable and cost-effective decoupling configurations that have negligible consequence on the array's characteristics such as bandwidth, gain and radiation efficiency, and physical footprint.

Photonics-assisted direction-of-arrival estimation of electromagnetic interference for GSM-R system in high-speed railways

In the field of high-speed railways (HSRs), electromagnetic interference (EMI) to the wireless train-ground communication system (e.g., the GSM-R system for train scheduling and dispatching) severely reduces the operational efficiency and even results in accidents. The direction-of-arrival (DoA) estimation of EMI is crucial for detection and removal. A photonics-assisted system is proposed to estimate the DoA of EMI for the GSM-R system along the HSRs in a remote and real-time mode. The proposed scheme is featured by simultaneous photonics-assisted detection and location (DoA estimation) of the EMI, with the advantages of strong EMI immunity, low loss transmission, and remote distribution. Here, an integrated optical multichannel transceiver operating as the photonic front end is used to acquire multiple delayed replicas of the electromagnetic signals, and then, a multiple signal classification algorithm is used to estimate their DoAs at the center station. In the indoor experiments, the DoAs ranging from −60 deg to +60 deg are successfully estimated with errors less than 1.2 deg in a 10-km radio-over-fiber link. In the field trials, the GSM-R signal accompanied by a suspected EMI is detected with DoA errors less than 1.8 deg.

A Comprehensive Comparison of EMI Immunity in CMOS Amplifier Topologies

This paper provides the results of a comprehensive comparison between complementary metal oxide semiconductor (CMOS) amplifiers with low susceptibility to electromagnetic interference (EMI). They represent the state-of-the-art in low EMI susceptibility design. An exhaustive scenario for EMI pollution has been considered: the injected interference can indeed directly reach the amplifier pins or can be coupled from the printed circuit board (PCB) ground. This is also a key point for evaluating the susceptibility from EMI coupled to the output pin. All of the amplifiers are re-designed in a United Microelectronics Corporation (UMC) 180 nm CMOS process in order to have a fair comparison. The topologies investigated and compared are basically derived from the Miller and the folded cascode ones, which are well-known and widely used by CMOS analog designers.

Smart Cutting Tool Integrated With Optical Fiber Sensors for Cutting Force Measurement in Turning

Real-time cutting force measurement is significantly important to monitor tool condition and machining process. Although commercial dynamometers are available for a range of machining applications, there is a lack of multipoint and low-cost measuring methods suitable for detecting cutting forces in harsh machining environments. In this paper, a smart cutting tool integrated with optical fiber sensors is first presented for cutting force measurements in turning. Fiber Bragg grating (FBG) sensors are employed to acquire cutting force information on cutting tools. Compared with the electrical and piezoelectric sensors, the proposed smart cutting tool has unique advantages such as electromagnetic interference immunity, explosion proof, ability to measure multiple cutting forces in the same and simplified data acquisition device with along-distance signal transmission, and enabling it to work in harsh machining environments. In addition, the proposed smart tool brings little effect on the structure and characteristics of machine tools due to FBGs’ small size and light weight. This paper investigates the operating principle of the sensory cutting tool theoretically and validates it using finite-element simulations. A prototype of the proposed device was developed and tested. Static calibration, dynamic identification experiment, and comparative cutting tests were conducted to evaluate its performances. The experimental results have shown that the cutting forces acquired by the developed smart tool are in good agreements with the results obtained by the reference commercial dynamometer. The proposed smart cutting tool has the potential to provide a new solution to the real-time measurement and monitoring of multipoint cutting forces in turning processes.

Review on fiber-optic sensing in health monitoring of power grids

Fiber-optic sensing technology is best adapted to health monitoring and evaluation of power grids because of its immunity of electromagnetic interference, capabilities of multiplexing and distributed sensing, and tolerance to harsh environments. We review key fiber-optic sensing technologies, including fiber Bragg gratings, fiber-optic interferometers, optical time domain reflectometries, and their applications in three main parts of power grids, transformers, power towers, and overhead transmission lines, during the past 20 years. In particular, optical fiber composite overhead ground wire and optical phase conductor applied in power grids are the areas of great potential to go further. The perspectives of an intelligent fault diagnosis subsystem for power grids based on a fiber-optic sensing network are discussed, and related on-going work is described. The review shall be of benefit to both engineers and researchers in power grids and fiber-optic sensing.

On-line Monitoring of SRM Grain Structure Based on embedded FBG Sensor

This paper proposes the use of FBG (Fiber Bragg grating) sensors for SRM (Solid Rocket Motor) grain structure continuous Structural Health Monitoring(SHM) as they are generally considered as the preferable solution in flammable and explosive environments, due to their electromagnetic interference immunity and their inherent electrical and explosion safe characteristics. The processes of SRM manufacturing(curing of propellant and demoulding) were monitored. The curing degree of the propellant can be monitored by wavelength change of the FBG sensors, and this provides a new monitoring method for curing of the propellant grain. The monitoring of the demoulding process shows that the sensor is very sensitive to the tensile and compressive stresses on grain and can be used for on-line monitoring of grain in a mechanical environment. In monitoring simulated debonding test, the failure process of crack initiation, expansion and direction all can be monitored by the FBG sensors. After the crack is produced, the location of the debonding can be determined by the variation of the different sensors.

Guided Wave-based System for Real-time Cure Monitoring of Composites using Piezoelectric Discs and Phase-shifted Fiber Bragg Gratings.

A real-time, in-process cure monitoring system employing a guided wave-based concept for carbon fiber reinforced polymer (CFRP) composites was developed. The system included a single piezoelectric disc that was bonded to the surface of the composite for excitation, and an embedded phase-shifted fiber Bragg grating (PS-FBG) for sensing. The PS-FBG almost simultaneously measured both quasi-static strain and the ultrasonic guided wave-based signals throughout the cure cycle. A traditional FBG was also used as a base for evaluating the high sensitivity of the PS-FBG sensor. Composite physical properties (degree of cure and glass transition temperature) were correlated to the amplitude and time of arrival of the guided wave-based measurements during the cure cycle. In addition, key state transitions (gelation and vitrification) were identified from the experimental data. The physical properties and state transitions were validated using cure process modeling software (e.g., RAVEN®). This system demonstrated the capability of using an embedded PS-FBG to sense a wide bandwidth of signals during cure. The distinct advantages of a fiber optic-based system include multiplexing of multiple gratings along a single optical fiber, small size compared to piezoelectric sensors, ability to embed or surface mount, utilization in harsh environments, electrically passive operation, and electromagnetic interference (EMI) immunity. The embedded PS-FBG fiber optic sensor can monitor the entire life-cycle of the composite structure from curing, post-cure/assembly, and in-service creating "smart structures".

A Generic EMI-Immune Technique for Differential Amplifiers With Single-Ended Output

This paper presents a unique methodology to calculate the filtering capacitances of the OpAmp already reported in the literature. The methodology aims to show that there is an optimal solution that can be used to increase the electromagnetic interference (EMI) immunity of any OpAmp for a wide range of frequencies. By using this proposed methodology, an OpAmp structure that reduces the EMI effect is designed in standard $0.18 \mu \text{m}$ mixed-mode CMOS technology. Detailed mathematical analyses and simulation results are presented and discussed. Simulation results show that the maximum EMI-induced offset voltage in the frequency range from 1 MHz to 1 GHz for the OpAmp is 4.4 mV. In contrast, the standard Miller OpAmp exhibits a maximum EMI-induced offset voltage of 92.4 mV under the same operating conditions.

Interleaved Hybrid Converter With Simultaneous DC and AC Outputs for DC Microgrid Applications

This paper proposes an interleaved hybrid converter (IHC) with simultaneous dc and ac outputs for dc microgrid applications. The IHC is realized by interleaving two conventional boost converters and replacing the active switch of lower boost converter by an H-bridge voltage source inverter. This arrangement enables the proposed IHC to operate at the condition where the sum of duty ratio ( $\boldsymbol{D}$ ) and modulation index ( $\boldsymbol{M}$ ) can be more than or equal to one, i.e., $ \boldsymbol{D} + \boldsymbol{M} \geq 1$ , unlike the conventional hybrid converters. The proposed IHC is capable of giving dc with high voltage gain and improved ac with reduced harmonic distortion. Due to interleaving nature of the IHC, input current is shared between the power converters and thus enables the use of low current rated switching devices and lower values of inductors. This results in reduced power losses and increased efficiency as compared to the conventional hybrid converters. The IHC also has inherent shoot-through protection capability, better electromagnetic interference immunity, and reliability. A modified unipolar sinusoidal pulse width modulation technique is used to control the power flow of the IHC. Detailed mathematical modeling of the proposed IHC is carried out and its steady-state behavior is validated through experimental results on a 500 W laboratory prototype.

Towards Optical Partial Discharge Detection with Micro Silicon Photomultipliers.

Optical detection is reliable in intrinsically characterizing partial discharges (PDs). Because of the great volume and high-level power supply of the optical devices that can satisfy the requirements in photosensitivity, optical PD detection can merely be used in laboratory studies. To promote the practical application of the optical approach in an actual power apparatus, a silicon photomultiplier (SiPM)-based PD sensor is introduced in this paper, and its basic properties, which include the sensitivity, pulse resolution, correlation with PD severity, and electromagnetic (EM) interference immunity, are experimentally evaluated. The stochastic phase-resolved PD pattern (PRPD) for three typical insulation defects are obtained by SiPM PD detector and are compared with those obtained using a high-frequency current transformer (HFCT) and a vacuum photomultiplier tube (PMT). Because of its good performances in the above aspects and its additional advantages, such as the small size, low power supply, and low cost, SiPM offers great potential in practical optical PD monitoring.

Design of A Novel Highly EMI-Immune CMOS Miller OpAmp Considering Channel Length Modulation

This paper presents a novel CMOS Miller operational amplifier (OpAmp) that has high immunity to electromagnetic interference (EMI). The proposed CMOS Miller OpAmp uses the replica concept with the source-buffered technique in order to achieve high EMI immunity across a wide range of frequencies (10 MHz to 1 GHz). The proposed amplifier is designed using the first-order quadratic mathematical model. The modeling includes the body effect and channel length modulation. The circuit has been fabricated using 0.18 $\mu \text{m}$ mixed-mode CMOS technology. Measurement results illustrate how the proposed Miller OpAmp reduces susceptibility to EMI even in the presence of high-amplitude interferences that are as high as 1 Vpp. Experimental results show that the maximum EMI-induced output offset voltage for the proposed Miller OpAmp is less than 10 mV over a wide range of frequencies (10 MHz to 1 GHz) when a 900 mVpp EMI signal is injected into the noninverting input. In contrast, the classic Miller OpAmp generates a maximum output offset voltage of 215 mV at 1 GHz under the same operating conditions. The measured results of the EMI-induced input offset corroborates the circuit simulations.

A Coupled Inductor Based High Boost Inverter with Sub-unity Turns-Ratio Range

Voltage source inverter cannot provide an output voltage higher than its input and needs a dead-time scheme for its switches to prevent dc-link short circuit due to spurious turn-on of switches by electromagnetic interference (EMI). Impedance source inverters have eliminated these disadvantages by providing boost functionality with improved EMI immunity. Coupled inductor-based impedance source inverters provided increased gain at the expense of increased coupled inductor turns-ratio. In this paper, a coupled inductor based high gain inverter is proposed, which achieves higher gain by increasing the coupled inductor turns-ratio $(n = n_{2}/n_{1})$ within a very narrow turns-ratio range of $0 \leq n , which is a major improvement over the other coupled inductor based high boost impedance source inverters. The proposed inverter, named Improved Trans–Current–Fed Switched Inverter, is described along with its equivalent operating states and relation between its input and output variables are derived. The steady-state inverter waveforms are shown using PSpice simulations. The operation of the inverter is validated by the experimental results, which show strong correlation with the theoretical analysis. A 110-V RMS ac output is obtained from 26-V dc input using a coupled inductor with turns-ratio of 0.33 to demonstrate its high-boost operation.

Ultra Low Voltage and Low Power Biopotential Amplifier with High Electromagnetic Interference Immunity

Ultra Low Voltage and Low Power Biopotential Amplifier with High Electromagnetic Interference Immunity

Indoor Positioning for Multiphotodiode Device Using Visible-Light Communications

With the widespread use of light-emitting diodes (LEDs) for lighting, their ability to support communications through visible light has become promising for various wireless applications. In particular, visible-light communication (VLC) assisted indoor positioning enjoys its unique advantage of electromagnetic interference immunity and high accuracy. Instead of directly extending conventional wireless positioning using radio-frequency equipment, we consider the indoor positioning specified for a popular VLC scenario where the target device has multiple photodiodes (PDs) while having no help from other fixed receiving nodes with known coordinates. A general framework is presented for multi-PD device positioning by exploiting relative positions, as well as the received signal strength indications, of the multiple PDs. Moreover, the feasible condition for realizing effective positioning is also presented. Finally, we validate the accuracy of the proposed method via numerical tests.

Ultra-Wideband and Adaptive Photonic Signal Processing of Microwave Signals

Microwave photonic techniques are attractive for processing high bandwidth signals, overcoming inherent electronic limitations. These processors provide new capabilities for realizing adaptive processing over extremely wide microwave frequency ranges, ultra-wideband operation, and electromagnetic interference immunity. In-fiber signal processors are inherently compatible with fiber-wireless systems, and can provide connectivity with in-built signal conditioning. Recent new methods in wideband microwave photonic processing are presented, including ultra-wideband phase shifters and true time delays for phased array beamforming, widely tunable single passband filters, switchable microwave photonic filters, wideband photonic mixers, high-resolution multiple frequency microwave photonic measurement systems, and photonic RF memory structures.