Input Current Range Research Articles

Flux transfer circuits breaking conventional limit in transfer coefficient based on a negative inductance of a π-junction

We have demonstrated transfer coefficients breaking the conventional limit in flux transfer circuits (FTCs) by introducing a π-phase-shifted Josephson junction (π-junction), where the FTCs include an input/output inductor. According to the current-phase relationship of a π-junction, the π-junction behaves as an inductor with intrinsically negative kinetic inductance. When a single-π-junction superconducting quantum interference device (π-SQUID) in which a geometric inductor is placed in parallel with the π-junction is formed, a current flowing on the inductor, that is, the internal flux is increased against an input current or an input flux supplied externally to the π-SQUID in case that the π-SQUID shows no hysteresis in characteristics of internal-external flux. The FTC under investigation (π-FTC) is composed of two identical π-SQUIDs sharing a π-junction. The magnitude of the internal flux exceeds that of the external flux in the π-SQUID near zero external flux. Using this effect, the transfer coefficients are expected to be increased in the π-FTCs. Numerical analysis for π-FTCs reveals that the transfer coefficients exceed the conventional limit in a wide range of input currents corresponding to the input flux, although the negative kinetic inductance depends on the magnitude of the input. We made several π-FTCs for critical currents of the π-junctions of 50 πA and 60 πA. The output flux was measured by constructing a flux-locked loop. The experimentally obtained ratios of the transfer coefficients of the π-FTCs to the coefficient of the conventional FTC made on the same chip agree with the numerical results, which supports the negative kinetic inductances cause the increased coefficients breaking the conventional limit. Because the transfer coefficient is almost independent of input currents, we believe that the π-FTCs are applicable for strengthening not only couplings used in quantum annealers or SQUID sensors but also couplings used in superconductor digital circuits.

A Fully Differential CMOS Current Memory Cell for Space-Embedded Analog-to-Digital Converters

This paper presents a radiation-hardened high-resolution current memory cell (CMC) that can be used to implement current-mode analog-to-digital converters (ADCs) for space-embedded, charge-coupled device processors. This CMC is based on a fully differential structure and on the Miller effect to reduce charge-injection errors. Using a commercial 0.35-μm 3.3-V complementary metal-oxide-semiconductor (CMOS) process, the radiation tolerance of this CMC has been enhanced by designing enclosed n-channel MOS transistors, using p-channel MOS switches only, and introducing guard rings wherever necessary. Results show that the CMC accuracy is 10 bits and that its estimated linearity error is &3x000B1;50 nA for a [-200 μA; 200 μA] dynamic input current range. Experimental results point out that signal-dependent charge injections are divided 23 times at least, which improves the CMC accuracy by approximately 4 bits. The measured acquisition time for a 200-μA input step transition to achieve a 10-bit settling accuracy is 50 ns. The active chip area and the power consumption of the proposed CMC are 0.042 mm 2 and 6 mW, respectively.

A single phase modified Y-source inverter with high voltage gains and reduced switch stresses

Abstract This study is dedicated to develop a single-phase modified Y-source inverter (m-YSI) topology having a high boost factor and low switch voltage stress by adding a switch to the low voltage region. Thanks to this structure, continuous input current and wide control range are achieved regardless of winding factor. Since an external switch is used in the recommended modified Y-source inverter, the modulation index and duty ratio are controlled independently. Detailed analyses of the modified Y-source inverter were performed using Matlab/Simulink and its performance was compared with conventional Y-source inverters. Compared to selected conventional Y-source inverters, the proposed m-YSI has almost three times less voltage stress. A lower-cost topology has been obtained in which state-of-the-art control methods can be applied, thanks to a wide control range and circuit components with a low power ratio. This proposed model can be used as a double-stage micro-inverter in photovoltaic systems.

An 8nA-512μA Current-to-Digital Converter With Mixed-Signal Coarse-Fine Subrange Normalization

This brief presents a current to digital convertor (CDC) with low power, wide dynamic range and fast conversion speed. Proposed coarse converter extends the maximum input current range, and achieves fast conversion speed with the input adaptive control scheme. Capacitive transimpedance amplifier (CTIA) based fine converter digitizes the residue current and achieves fine resolution. Proposed mixed-signal coarse-fine subrange normalization technique enables seamless processing of the final converter output. The proposed CDC implemented in 0.18 μm CMOS process converts input current up to 512 μA with 7.8125nA resolution and 400 μs conversion time. Power consumption is 79.4 μW.

Design and Development of a Traveling Wave Ferro-Microfluidic Device and System Rig for Potential Magnetophoretic Cell Separation and Sorting in a Water-Based Ferrofluid.

The timely detection and diagnosis of diseases and accurate monitoring of specific genetic conditions require rapid and accurate separation, sorting, and direction of target cell types toward a sensor device surface. In that regard, cellular manipulation, separation, and sorting are progressively finding application potential within various bioassay applications such as medical disease diagnosis, pathogen detection, and medical testing. The aim of this paper is to present the design and development of a simple traveling wave ferro-microfluidic device and system rig purposed for the potential manipulation and magnetophoretic separation of cells in water-based ferrofluids. This paper details in full: (1) a method for tailoring cobalt ferrite nanoparticles for specific diameter size ranges (10-20 nm), (2) the development of a ferro-microfluidic device for potentially separating cells and magnetic nanoparticles, (3) the development of a water-based ferrofluid with magnetic nanoparticles and non-magnetic microparticles, and (4) the design and development of a system rig for producing the electric field within the ferro-microfluidic channel device for magnetizing and manipulating nonmagnetic particles in the ferro-microfluidic channel. The results reported in this work demonstrate a proof of concept for magnetophoretic manipulation and separation of magnetic and non-magnetic particles in a simple ferro-microfluidic device. This work is a design and proof-of-concept study. The design reported in this model is an improvement over existing magnetic excitation microfluidic system designs in that heat is efficiently removed from the circuit board to allow a range of input currents and frequencies to manipulate non-magnetic particles. Although this work did not analyze the separation of cells from magnetic particles, the results demonstrate that non-magnetic (surrogates for cellular materials) and magnetic entities can be separated and, in some cases, continuously pushed through the channel based on amperage, size, frequency, and electrode spacing. The results reported in this work establish that the developed ferro-microfluidic device may potentially be used as an effective platform for microparticle and cellular manipulation and sorting.

Current sensor based on diamond nitrogen-vacancy color center

High precision current measurement is very important for the calibration of various high-precision equipment and the measurement of other precision detection fields. A new current sensor based on diamond nitrogen-vacancy (NV) color center magnetic measurement method is proposed to realize the accurate measurement of current. This new current method can greatly improve the accuracy of current measurement. Experiments show that the linearity of the current sensor based on diamond NV color center can reach up to 33 ppm, which is superior to other current sensors and solves the problem of low linearity. When the range of input current is 5–40 A, the absolute error of the calculated current is less than 51 μA, and the relative error is 2.42 × 10−6 at 40 A. Combined with the research content and results of the experiment, the application of the current sensor in the field of current precision measurement is prospected.

A Power/Hardware-Efficient SiPM Readout IC Embedded in a Boost Converter for Mobile Radiation Dosimeters

A radiation detection system provides radiation intensity to protect human life from hazardous radiation. However, the prior portable radiation detection system (mobile radiation dosimeter) structures had a problem in that various subsystems had to be designed with complex circuits. First, since the radiation detector must be driven by a relatively high voltage, a high-efficient boost converter that can receive the battery voltage and generate a high bias voltage must be implemented. Second, sophisticated sensor interface circuits that can convert the analog signal generated by the radiation detector to digital value must also be implemented. To reduce the complexity of the mobile radiation dosimeters, a power- and hardware-efficient radiation detection system IC is presented for mobile radiation dosimeters. The current value of a silicon photomultiplier (SiPM) used as a radiation detector is sensed from the control information of a boost converter in the process of regulating a voltage to bias the SiPM. Due to this embedded sensing function, no additional hardware and power consumption are required for implementing and operating separate sensor interface circuits while providing sufficient radiation sensing performance. The implemented radiation detection system IC achieves 0.217- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> input referred noise performance over 1-kHz signal bandwidth and 10-mA maximum allowable linear input current range. In addition, the proposed dc–dc boost converter can generate a high enough voltage (∼27 V) to drive SiPM from a lithium-ion battery with an efficiency of 72%. The irradiation test with radiation check source ( <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">137</sup> Cs) demonstrates that the bias voltage is well regulated in the presence of high-energy radiation particles.

Common-Ground Grid-Connected Five-Level Transformerless Inverter With Integrated Dynamic Voltage Boosting Feature

A single-phase common-ground five-level (5L) inverter with a dynamic voltage conversion gain and capability of operating in a wide input voltage range and a single-stage energy conversion configuration is presented in this article. The proposed topology requires nine active power switches and is comprised of an integrated switched-boost (SB) module connected in series to a switched-flying-capacitor (SFC) cell. Two self-balanced capacitors with a single boost inductor in the integrated SB module are employed to generate a 5L output voltage waveform with a dynamic voltage conversion gain. The current stress profile of all the active and passive elements is kept within a permissible input current range. By adopting an extra diode-capacitor-inductor network into the integrated SB module and with the utilization of the same SFC cell, the proposed topology is extended to achieve a quadratic voltage conversion gain while retaining the quality of ac voltage waveform. Theoretical analysis, closed-loop control/modulation principles, design guidance, comparative study, and relevant experimental results obtained from a 1.5-kW laboratory-built prototype are presented to ascertain the operation and feasibility of the proposed system.

Novel Resistorless, Cascadable Current-Mode Precision Rectifier Using CFDITA

The paper introduces a new circuit structure of precision full-wave rectifier, without the requirement of any diode(s) and passive component(s), which operates in current mode. The proposed structure of the rectifier employs a single current follower differential input transconductance amplifier and two MOS transistors only. The use of the least number of active components makes the circuit structure simple and favorable to the contemporary integration technology. The proposed rectifier has wider input current dynamic range (±1.6 mA), lower current offset (84 pA), and can operate up to 30 MHz frequency. Additionally, the circuit is easily cascadable, temperature insensitive, and less affected by process variation, MOS transistors mismatch, and supply voltage variation. The rectifier circuit is verified through 0.18 µm gpdk technology-based post-layout simulation results using the cadence Virtuoso tool. The rectification accuracy is examined through the parameters, such as average value ratio and root mean square error. The proposed rectifier’s layout measures 31.95 µm × 31.35 µm in size.

1 V, 20 nW True RMS to DC Converter based on Third Order Dynamic Translinear Loop

This paper presents a novel current-mode true RMS–DC converter based on the dynamic translinear principle. The converter is designed using a third-order translinear loop, resulting in a very compact and simple circuit. The proposed circuit is designed in 65 nm CMOS technology, operates with 1 V power supply, has only 14 transistors and performs satisfactorily over a wide input current range of 300 nA–950 nA and for a frequency range of 600 Hz–650 kHz for a capacitance value of 10 nF. The frequency range of operation can be tuned by varying the external off chip capacitor and the bias current. The circuit consumes 20 nW static power, 1.6 μW maximum dynamic power and offers the lowest FOM among the other RMS–DC converter circuits presented in the literature. Comprehensive mathematical analysis along with the post layout simulation results confirm the validity of the proposed circuit. To test the use of converter in real world scenarios, the proposed converter is introduced within a typical ECG detection system and the results show that the circuit is an attractive solution for RMS–DC conversion in low-voltage low-power applications.

Power Converter Solutions for Industrial PV Applications—A Review

As the use of photovoltaics becomes more widespread, new technologies for more efficient energy generation, transmission, and distribution based on power electronics converters are being developed. The most common applications are grid-on, energy storage, hybrid, and high voltage gain applications. These applications impose several additional requirements in the design of power converters associated with the solar battery’s maximum power tracking and operation in a wide range of input currents and voltages. The practical realization of such solutions can be implemented on the basis of various topologies, which requires a preliminary application of criteria for assessing their effectiveness. The paper conducts a comparison of different topologies on power converters based on two parameters that describe their cost and power loss for various PV applications. For a straightforward study, these parameters are represented using the gain factor, which allows for an accurate comparison of the efficiency of various types of converters.

Fuzzy System Design Using Current Amplifier for 20 nm CMOS Technology

In the recent decade, different researchers have performed hardware implementation for different applications covering various areas of experts. In this research paper, a novel analog design and implementation of different steps of fuzzy systems with current differencing buffered amplifier (CDBA) are proposed with a compact structure that can be used in many signal processing applications. The proposed circuits are capable of wide input current range, simple structure, and are highly linear. Different electrical parameters were compared for the proposed fuzzy system when using different membership functions. The novelty of this paper lies in the electronic implementation of different steps for realizing a fuzzy system using current amplifiers. When the power supply voltage of CDBA is 2 V, it results in 155 mW, power dissipation; 4.615 KΩ, input resistance; 366 KΩ, output resistances; and 189.09 dB, common-mode rejection ratio. A 155.519 dB, voltage gain, and 0.76 V/μs, the slew rate is analyzed when the power supply voltage of CDBA is 3 V. The fuzzy system is realized in 20 nm CMOS technology and investigated with an output signal of high precision and high speed, illustrating that it is suitable for real-time applications. In this research paper, a consequence of feedback resistance on the adder circuit and the defuzzified circuit is also analyzed and the best results are obtained using 100 K resistance. The structure has a low hardware complexity leading to a low delay and a rather high quality.

Influence of Magnetostriction Induced by the Periodic Permanent Magnet Electromagnetic Acoustic Transducer (PPM EMAT) on Steel.

The periodic permanent magnet electromagnetic acoustic transducer (PPM EMAT) is a sensor that can generate and receive shear horizontal (SH) waves without direct contact with the inspected medium using the Lorentz mechanism. However, the PPM EMAT experiences high signal variance on ferromagnetic steel under specific conditions, such as a change in signal amplitude when the sensor is moved in the direction of SH wave propagation. Magnetostriction effects are hypothesized to be the cause of these anomalous behaviors; the objective of this paper is to determine the relative strengths of the magnetostriction and Lorentz wave generation mechanisms for this type of EMAT on steel. This goal is accomplished through the use of a second EMAT, which induces only magnetostriction (MS-EMAT), to calibrate a novel semi-empirical magnetostriction model. It is found that magnetostriction effects reduce the amplitude of the SH wave generated by this particular PPM EMAT transmitter by an average of 29% over a range of input currents. It is also determined that magnetostriction is significant only in the investigated PPM EMAT transmitter, not the receiver. In terms of practical application, it is shown that the MS-EMAT is less sensitive to changes in the static and dynamic fields than PPM EMATs at specific operating points; this makes the MS-EMAT a viable alternative for nondestructive evaluation despite lower amplitudes.

A Low Noise 28Gbaud/s Linear PAM4 Receiver Front-End for Optical Communication Applications in 0.13μm BiCMOS Technology

This paper presents a low noise 28 Gbaud/s linear receiver front-end for fourth-order pulse amplitude modulation (PAM4) signal applied in the field of optical communication. The designed receiver front-end includes a transimpedance amplifier(TIA), an automatic gain control (AGC) and a DC offset cancellation (DCOC) circuit. The pseudo-differential structure of the TIA is designed to achieve low noise. The resistance and capacitance degradation technology are introduced in the variable gain amplifier(VGA) and the equalizer(EQ) to improve linearity and optimize the bandwidth. In the AGC mode, the feedback loop controls the output amplitude to be a desired value within a large range of input current. The PAM4 optical receiver front-end achieves a maximum differential transimpedance gain of 76 dBΩ and -3dB bandwidth of 27 GHz. The equivalent input noise current density with the front-end circuit is . In 0.13µm BiCMOS technology, the PAM4 front-end chip consumes 200 mW with a 3.3V voltage supply.

A Four-Phase Interleaved Buck-Boost Converter With Changed Load Connection for the Fuel Cell Activation

When the fuel cell (FC) is being activated before used in industrial applications, a power conditioner is needed to interface the FC with the load. Due to low current ripples, high output power, and simple structure, the multi-phase interleaved non-isolated DC-DC converter is most suitable for the power conditioner. This paper proposed, analyzed and designed a four-phase interleaved buck-boost converter with changed load connection (CLC-FIBC) for the FC activation with characteristics as simple structure, wide input current, high current, and low current ripples. The operating principle and mathematical model of the CLC-FIBC were firstly analyzed, derived and presented, and then mathematical equations of transistor voltage stress and inductor current ripple are derived respectively. Besides, this CLC-FIBC was compared with several DC-DC converters to prove the superiority. The simulation and experimental prototype was built to validate the theoretical analysis after presenting some design considerations. Simulation and experimental results show that the CLC-FIBC has characteristics of both step up/down function, high power, wide input current range, and low current ripples.

Enhancement of luminous flux of InGaAlP-based low-power SMD LEDs using substrates with different thermal resistances

PurposeOptimization of light-emitting diodes’ (LEDs’) design together with long-term reliability is directly correlated with their photometric, electric and thermal characteristics. For a given thermal layout of the LED system, the maximum luminous flux occurs at an optimal electrical input power and can be determined using a photo-electro-thermal (PET) theory. The purpose of this study is to extend the application of the luminous flux equation in PET theory for low-power (LP) LEDs.Design/methodology/approachLP surface-mounted device LEDs were mounted on substrates of different thermal resistances. Three LEDs were attached to substrates which were flame-retardant fiberglass epoxy (FR4) and two aluminum-based metal core printed circuit boards (MCPCBs) with thermal conductivities of about 1.0 W/m.K, 2.0 W/m.K and 5.0 W/m.K, respectively. The conjunction of thermal transient tester and thermal and radiometric characterization of LEDs system was used to measure the thermal and optical parameters of the LEDs at a certain range of input current and temperature.FindingsThe validation of the extended application of the luminous flux equation was confirmed via a good agreement between the practical and theoretical results. The outcomes show that the optimum luminous flux is 25.51, 31.91 and 37.01 lm for the LEDs on the FR4 and the two MCPCBs, respectively. Accordingly, the stipulated maximum electrical input power in the LED datasheet (0.185 W) is shifted to 0.6284, 0.6963 and 0.8838 W between the three substrates.Originality/valueUsing a large number of LP LEDs is preferred than high-power (HP) LEDs for the same system power to augment the heat transfer and provide a higher luminous flux. The PET theory equations have been applied to HP LEDs using heatsinks with various thermal resistances. In this work, the PET theory luminous flux equation was extended to be used for Indium Gallium Aluminum Phosphide LP LEDs attached to the substrates with dissimilar thermal resistances.

Altered neuronal excitability in a Hodgkin-Huxley model incorporating channelopathies of the delayed rectifier potassium channel.

Channelopathies involving acquired or genetic modifications of the delayed rectifier K+ channel Kv1.1 include phenotypes characterized by enhanced neuronal excitability. Affected Kv1.1 channels exhibit combinations of altered expression, voltage sensitivity, and rates of activation and deactivation. Computational modeling and analysis can reveal the potential of particular channelopathies to alter neuronal excitability. A dynamical systems approach was taken to study the excitability and underlying dynamical structure of the Hodgkin-Huxley (HH) model of neural excitation as properties of the delayed rectifier K+ channel were altered. Bifurcation patterns of the HH model were determined as the amplitude of steady injection current was varied simultaneously with single parameters describing the delayed rectifier rates of activation and deactivation, maximal conductance, and voltage sensitivity. Relatively modest changes in the properties of the delayed rectifier K+ channel analogous to what is described for its channelopathies alter the bifurcation structure of the HH model and profoundly modify excitability of the HH model. Channelopathies associated with Kv1.1 can reduce the threshold for onset of neural activity. These studies also demonstrate how pathological delayed rectifier K+ channels could lead to the observation of the generalized Hopf bifurcation and, perhaps, other variants of the Hopf bifurcation. The observed bifurcation patterns collectively demonstrate that properties of the nominal delayed rectifier in the HH model appear optimized to permit activation of the HH model over the broadest possible range of input currents.

Impact of Mechanical Property Degradation and Intermetallic Compound Formation on Electromigration-Oriented Failure of a Flip-Chip Solder Joint

Due to the increased complexity and optimization in microprocessor packaging from 2D to 3D packages, the size of solder joints is being reduced significantly. This trend currently leads to an increased amount of current density across flip-chip solder joints as well as microbumps and causes electromigration-oriented void formation and subsequent failure of the solder joints. It has been observed from literature that solder material undergoes microstructure evolution and subsequent degradation of mechanical properties under isothermal aging conditions. The current study is based on the effects of material property degradation due to thermal aging of flip-chip Sn-Ag-Cu (SAC) solder joints on electromigration-oriented failure. Finite element analysis has been used to analyze the diffusion characteristics of a SAC solder joint under isothermal aging conditions of 100°C for a period of 1–20 days, and electromigration simulation has been performed at two different temperatures of 100°C and 125°C for 100 h at an input current range of 0.01–0.05 A. The effect of intermetallic compound (IMC) layer thickness is analyzed to reveal the impact on electromigration-oriented failure in isothermally 60 days long aged solder bumps. Results have revealed that resistance to electromigration-oriented failure is higher in the case of aged components compared to unaged components along with the increment of time to failure with IMC formation in the SAC solder joint.

Time-Based Sensor Interface for Dopamine Detection

This paper describes the design of an integrated sensor interface for dopamine detection. The sensor interface circuit fabricated in 65 nm CMOS technology utilizes a time-based analog-to-digital conversion circuit built around a ring oscillator. The circuit supports a wide input current range of $\pm 1.2~\mu \text{A}$ and sampling rate of 1 - 20 kHz, enabling sub-second detection of neurochemicals within the supported current range. Measured results with physiologically relevant dopamine concentration of 500 nM demonstrate the ability of the sensor interface circuit to detect oxidation and reduction current peaks, which provides information about the release times and redox potentials of the neurochemical. This chemical information is essential in neurostimulation treatment of neurological and neurodegenerative diseases.

The geometry of rest\u2013spike bistability

Morris–Lecar model is arguably the simplest dynamical model that retains both the slow–fast geometry of excitable phase portraits and the physiological interpretation of a conductance-based model. We augment this model with one slow inward current to capture the additional property of bistability between a resting state and a spiking limit cycle for a range of input current. The resulting dynamical system is a core structure for many dynamical phenomena such as slow spiking and bursting. We show how the proposed model combines physiological interpretation and mathematical tractability and we discuss the benefits of the proposed approach with respect to alternative models in the literature.