Power Supply Rails Research Articles

Template models of silicon carbide JFETs and their practical applications in high-temperature analog chip design problems in LTspice environment

Modern achievements of leading microelectronic firms in the field of designing operational amplifiers (Op-Amp) and their functional units based on silicon carbide, designed for operation in the temperature range up to 300-600 °C, are analyzed. Numerical values of the parameters of existing high-temperature operational amplifiers, created for space missions of NASA Research Center named after Gallen, on the open-circuit voltage gain, the systematic component of the zero offset voltage, the frequency of single gain, the maximum rate of increase of the output voltage, the coefficient of attenuation of input in-phase signals and the coefficient of suppression of interference on the power supply rails, as well as information on the experimental characteristics of Op-Amps during long-term operation at high temperatures and exposure to radiation. To model circuits at temperatures up to 450 °C, template models of SiC transistors (TM) have been developed using the template modeling technique, in which constant model parameters are replaced by fractional-rational functions (Padé approximation), allowing to describe more accurately the physical processes in JFETs without violating the nature of their changes. For the freely distributable modeling environment LTspice the instruction for application of the TM is developed. Circuit solutions of high-temperature basic analog functional units realized on the basis of silicon carbide field-effect transistors are considered. The basic characteristics of SiC source repeaters, SiC differential stages and the simplest SiC operational amplifiers based on them at temperatures of 25 °C and 452 °C are investigated. The obtained results are recommended to be used in the design of high-temperature operational and instrumental amplifiers in space instrumentation, deep well drilling, automotive industry, nuclear reactors, etc.

An ultra-low power adjustable current-mode analog integrated general purpose artificial neural network classifier

This study introduces a methodology tailored to analog hardware architecture for implementing an artificial neural network. The fundamental components of the architecture include current-mode circuits, representing the class, and a voltage-mode comparator. Specifically, the current mode circuits comprise the Mahalanobis distance circuit, Sigmoid function circuit, analog multiplier, and current mirrors. Regarding the voltage comparator, which receives the final decision, a folded-cascode operational amplifier is employed. The operational principles of the architecture are extensively explained and applied in a power-efficient configuration (operating under 976nW) with low power supply rails (0.6 V). The proposed implementation is tested on real-world biomedical classification tasks, achieving classification accuracy exceeding 91.6%. The designs are implemented using a 90nm CMOS process and developed using the Cadence IC Suite for both schematic and layout design. Monte-Carlo analysis, encompassing both process and mismatch, as well as corner analysis, are provided to confirm the robust characteristics of the proposed classifier. Through comparative analysis of post-layout simulation results with an equivalent software-based classifier and related literature, the proper operation of the proposed architecture is confirmed.

Analysis of Leakage Current in Dynamic Wireless Power Transfer Systems Based on LCC-S Architecture

This paper investigates the issue of leakage current at the transmitter in the Dynamic Wireless Power Transfer (DWPT) system for electric vehicles and puts forward a novel bilateral resonant compensation topology structure based on the conventional LCC-S architecture. Based on the LCC-S framework, a circuit model was developed for traditional (unilateral)/bilateral resonant compensation topologies. The Fourier series voltage-to-earth expansions for the power supply rail were deduced for both topologies. Subsequently, the voltage-to-earth waveforms for the power supply rail were obtained by utilizing the Fourier series expansions of the voltage-to-earth and the corresponding circuit simulation models. The results demonstrate the efficacy of the bilateral resonant compensation topology in mitigating higher-order harmonics of the voltage to earth on the power supply rail by effectively suppressing the distortion in the leakage current and minimizing its conduction. The effectiveness of the double-ended resonant compensation topology in suppressing leakage current conduction has been verified through experimental tests and waveform comparisons of the voltage to earth and leakage current on the power supply rail under two different topologies. Through experimental testing, during which the unilateral/bilateral resonant compensation topologies were compared, an analysis was conducted on the waveforms of the voltage to earth and leakage current of the power supply rail. The results verified the effectiveness of the bilateral resonant compensation topology in mitigating the conduction of leakage current. This study provides empirical evidence supporting the use of the bilateral resonant compensation topology for suppressing leakage current in power rail applications.

Protection method of traction power supply system for low and medium speed Maglev traffic based on fault traveling wave features

AbstractLow and medium speed magnetic levitation traffic with short power supply distance and complex grounding network structure, prone to power supply rail grounding faults. However, the existing fault location methods do not accurately locate the fault point, making it difficult for the protective device to act to cut off the fault. To address the above problems, this paper builds a dynamic simulation model of the low and medium speed magnetic levitation power supply rails to study the distribution characteristics of the fault traveling waves after a ground fault occurs in the power supply rails, and analyses the generation mechanism of the traveling wave spectrum through formula calculation. First, the difference in current between the positive and negative bus bars is analyzed to determine whether a ground fault has occurred. Second, the direction of the current difference between stations is compared to locate the faulty section. Finally, the fault distance is calculated from the frequency difference of the fault voltage at the double‐ended station. Through simulation, the method is validated to be unaffected by fault location, fault transition resistance, noise interference, and is applicable to short circuit faults caused by lightning strikes, and the ranging error always remains within 20 m. The method has strong robustness, can effectively solve the problem of protection misoperation and accurately locate the fault point. It is suitable for low and medium speed magnetic levitation transportation power supply rail ground fault.

An Economical DWPT System With Mutual Compensation of Segmented Power Supply Rails Based on LCL Topology

For high-power, long-mileage dynamic wireless power transfer (DWPT) system, its economy and adaptability to complex working conditions are the main factors limiting its popularization and application. In this paper, the compensation and power supply of segmented rails are studied, and a DWPT system with mutual compensation of segmented power supply rails based on LCL topology is constructed. By multiplexing components, the number, cost and volume of devices are reduced, and the economy of the system is improved. The power supply topology is optimized to achieve constant-current characteristics over a wide load range to generate a stable high-frequency magnetic field in space and avoid short-circuit current induced by mutual coupling of adjacent rail. The resonant control conditions of the system are derived, and a phase shift control method based on the three-leg inverter is proposed to realize the full range regulation of transmitter current and output power, and improve the adaptability of the system. The characteristics of the proposed DWPT system have been verified by an experimental prototype.

The traction network design of the new three‐phase 3‐kV traction power supply system based on the limits of receiving‐end voltages and negative sequence voltage unbalance factor

AbstractThe characteristics of traction network (TN) of the three‐phase 3‐kV traction power supply system (TPSS) are: three‐phase conductors are flat layout (layout‐1, layout‐2); the material and cross‐section of conductors are ferromagnetic and irregular, respectively. So the phase impedance matrix (PIM) is unbalanced and the closed‐form formula for conductor impedance is hard to get. To address these issues, firstly, the PIM is derived, and the cause of unbalance is revealed. From the perspective of structure optimization, a new flat layout (layout‐3) and an equilateral triangle layout (layout‐4) is proposed. Then, to calculate the wideband frequency self‐ and mutual impedances of the special phase conductors, a frequency‐ and current‐dependent closed‐form formula based on 4‐parameters equivalent tubular conductor (ETC) model is proposed. Furthermore, an equivalent TN circuit model at 50 Hz is established to calculate the receiving‐end voltage and its negative sequence voltage unbalance factor (NSVUF). Finally, using these two indexes, the performances of the layout‐1 to 4 are evaluated and compared. The results show that the conductor spacing and power supply frequency affect the two indexes much while the dimension of the power supply rail (PSR) not; layout‐4 can completely balance the receiving‐end voltage and improve its magnitude which can enhance the power supply capability.

Signal Amplification by Means of a Dickson Charge Pump: Analysis and Experimental Validation

Recently, with the aim of extending the use of the CP in all those applications where a time-variant signal must be amplified with its DC component above the positive power supply rail, the signal amplification feature of a conventional Dickson charge pump (CP) has been investigated, introducing a small-signal model for each particular condition in which a CP can work. In this paper this idea is further investigated, especially under the slow switching limit (SSL) condition, and experimental validation has been carried out using a 65 nm CMOS technology for four different voltage gain values. Starting from an equivalent model of the CP, the main small- and large-signal parameters are analytically derived and discussed in depth. As a proof of concept, experimental measurements on four CPs with different numbers of stages confirm the validity of this unconventional application and the effectiveness of the CP when used as an amplifier.

Comparative Analysis of the Design Techniques for Low Leakage SRAMs at 32nm

This paper presents a comprehensive overview of leakage reduction techniques prevailing in Static Random Access Memories (SRAMs) by classifying them in three categories namely latch, bitline and read port. The performance of the techniques are evaluated in terms of leakage reduction capability along with the impact on read performance and hold stability through extensive simulative investigations at 32 nm technology node by taking conventional SRAM cell as reference. Further, as SRAMs are susceptible to inter-die as well as intra-die process variations, the performance at different PVT corners is also captured to demonstrate the efficacy of each technique under PVT variations. It is found that among the techniques used for reducing latch leakages, Multi-threshold CMOS technique possess the highest leakage reduction capabilities followed by Drowsy mode and Substrate-bias techniques. The results also indicate that Negative word line technique is more effective at low supply voltages whereas the Leakage biased bitline technique is more effective at high supply voltages for reducing bitline leakages. Amongst the read port leakage reduction techniques, Stack-effect and Dynamic control of power supply rail techniques are capable of suppressing the leakages at high voltages whereas Virtual cell ground technique is more efficacious at low voltages. The impact of technology scaling on SRAM cell performance with leakage reduction techniques is also studied. For the sake of completeness, suggestions are put forward for adopting a particular technique to address leakages at latch, bitline and read port levels.

High-PSRR Wide-Range Supply-Independent CMOS Voltage Reference for Retinal Prosthetic Systems

This paper presents a fully integrated voltage-reference circuit for implantable devices such as retinal implants. The recently developed retinal prostheses require a stable supply voltage to drive a high-density stimulator array. Accordingly, a voltage-reference circuit plays a critical role in generating a constant reference voltage, which is provided to a low-voltage-drop regulator (LDO), and filtering out the AC ripples in a power-supply rail after rectification. For this purpose, we use a beta-multiplier voltage-reference architecture to which a nonlinear current sink circuit is added, to improve the supply-independent performance drastically. The proposed reference circuit is fabricated using the standard 0.35 µm technology, along with an LDO that adopts an output ringing compensation circuit. The novel reference circuit generates a reference voltage of 1.37 V with a line regulation of 3.45 mV/V and maximum power-supply rejection ratio (PSRR) of −93 dB.

EMI Effect in Voltage-to-Time Converters

This brief presents the effects of electromagnetic interferences in the Voltage-to-Time Converters (VTC), one of the most important circuits in Time-Mode Signal Processing. The VTC is based on two Voltage-Controlled Delay Units; it is designed in a standard 180nm CMOS technology and it is exposed to the electromagnetic interferences, picked up from the I/O pins and the power supply rails. The VTC circuits are susceptible to the interferences which can cause timing jitter and non linearity. It is found that the level of the susceptibility depends on the amplitude of the interferences, on their frequency and also on their initial phase.

A multi-field coupling model for the magnetic-thermal-structural analysis in the electromagnetic rail launch

The magnetic-thermal-structural performances (MTSP) in an electromagnetic rail launcher have a significant influence on the successful launch capability. However, it is difficult to explore the MTSP directly through the experimental measurement due to the approximately adiabatic processes in the in-bore environment of the launcher, which further limits us to understand the multi-field properties in the electromagnetic launch process. Considering the interaction between the magnetic field and the thermal field, a transient multi-field coupling model is proposed to investigate the MTSP for the electromagnetic launch based on the finite element method in this paper. The model validation is presented through a comparison of the model prediction with the experimental data of the magnetic flux density and the temperature. The MTSP for an electromagnetic railgun are then analyzed in detail with the effect of the pulse power supply parameter and rail sizes. The results show the pulse power supply parameter has a significant effect on the MTSP near the electromagnetic railgun breech and the rail damage can be decreased with a larger rail size. Moreover, we found the rail was most easily to damage at the rail edge position of the inner sidewall, which is consistent with the groove-shaped damage position in the rail after an experimental test. The results of these investigations will help improve the design of an electromagnetic launcher.

A Distributed Power Delivery Grid Based on Analog-Assisted Digital LDOs With Cooperative Regulation and IR-Drop Reduction

This paper introduces an on-chip distributed power delivery grid (DPDG) with cooperative regulation and IR-drop reduction based on analog-assisted digital LDOs (AADLDOs), which inherit the merits of low output ripple and sub-LSB current supply ability from the analog control, and the advantage of low supply voltage operation and adaptive fast response from the digital control. With the distributed power delivery topology, the IR-drop across the power supply rail can be reduced, especially in large area power-supply applications. The AADLDOs in the power delivery grid work cooperatively to obtain a balance between improved response speed and power consumption. A prototype of a 3 × 3 power grid with 9 AADLDOs, providing a total of 500-mA maximum load current with an on-chip 0.9-nF output capacitor, is fabricated in a 65-nm CMOS process to demonstrate the proposed DPDG concept and the effectiveness of this scheme. A maximum voltage undershoot of 125mV is measured with a 450mA/20ns load step, resulting a figure-of-merit as low as 0.249ps.

A Narrow-Rail Three-Phase Magnetic Coupler With Uniform Output Power for EV Dynamic Wireless Charging

For the EV dynamic wireless charging system, the conventional single-phase magnetic couplers with alternately arranged magnetic poles, such as I-type, S-type, and N-type, have both the advantage of narrow power supply rail and the disadvantage of large output power fluctuation. Although the conventional three-phase meander-type magnetic coupler uses the traveling wave magnetic field to ensure uniform output, a wide transmitter is required in order to provide a large air gap. This article proposes a narrow-rail three-phase magnetic coupler, which realizes the advantages of the above two kinds of couplers by integrating the narrow rail with uniform output power in one coupler. The magnetic field distribution and the working principle of the proposed coupler are illustrated and the receiver structure and the transmitter coil's winding method are optimized. Moreover, the effect of the interphase mutual inductance between different phases in transmitter coils on the system is analyzed. Finally, an experimental prototype was built for the verification. The experimental results showed that the fluctuation of output voltage was within ±2.5% during the dynamic charging process.

Mutual interference induced by single event effects in CMOS circuits

Single event effect (SEE) induced mutual interference in CMOS circuits, including single event (SE) induced coupling effects (crosstalk) and modulation in local supply voltage on power-supply rails, was studied based on the increase in metal interconnect density. The dependence of SE vulnerability on metal interconnects was experimentally investigated using heavy ions and pulsed laser. Numerical simulation was performed to evaluate the modulation in local supply voltage induced by SEEs. Two groups of test structures with various metal interconnects between well contacts and the first metal layer were designed and fabricated. All other parts, including well contacts in the active regions, are of the same structures. Experimental results show that the upset cross section decreases with an increase in metal interconnect contact (CT) density between the active region and the first metal layer, suggesting a dominant contribution of rail voltage drop induced by charge sharing rather than SE-induced crosstalk. The differences in upset cross sections with cells of different CT hole densities appear the most evident ones under low frequency and high linear energy transfer value conditions. When transient-induced upsets play a more important role, the differences get weakened due to masking effects.

A Dual-Layer Receiver With a Low Aspect Ratio and a Reduced Output Fluctuation for EV Dynamic Wireless Charging

A dual-layer receiver with a low aspect ratio and a low output fluctuation is proposed in this article. It is composed of three parts: full-pitch coils, mixed-pitch coils, and a flat receiver core. In EV dynamic wireless charging system, power supply rails with alternately arranged poles, such as I-type, S-type, and N-type rails, have the advantage of narrow width, but they also show the main drawback of sinusoidal output fluctuation when they are mated with conventional double D (DD) receiver coils. To solve this problem, a dual-layer receiver is proposed in this article. Through the combination of full-pitch coils and mixed-pitch coils, the output fluctuation factor can be reduced from 100% to 29%. Compared with the conventional dual-DD receiver, the proposed receiver shows the following advantages. Full-pitch and mixed-pitch coils are not required to be dislocated in space so that the aspect ratio is reduced by 20%. In this way, the problems of too large receiver size and limited installation space can be solved, and the cross coupling between the receiver coils can be eliminated as well. Based on the theoretical analysis of the working principle of the dual-layer receiver, the output voltage expression of receiver coils is derived and the basic relationship between full-pitch and mixed-pitch coils is explored. Then, the influences of the mixed-pitch coil's symmetry and vehicle chassis on the system are analyzed, and the design principle of the proposed receiver is given. In addition, the dual-layer receiver is extended to multiple receivers through multiple cascades to further reduce the output fluctuation factor. Finally, a 10-kW prototype with ac–dc efficiency of 93.2% was built for experimental verification. The experimental results were consistent with theoretical analysis and simulation results, thus proving that the proposed receiver could reduce the aspect ratio and achieve the decoupling between the receiver coils under the premise of reducing the output fluctuation.

Uniform Power Dynamic Wireless Charging System With I-Type Power Supply Rail and DQ-Phase-Receiver Employing Receiver-Side Control

Power fluctuation caused by the coupling variation is frequently observed in a dynamic wireless charging (DWC) system. To solve this problem, a uniform power solution based on the I-type power supply rail and DQ-phase-receiver is proposed employing receiver-side control. The outputs of DQ-phase voltages are series connected after rectifications to get a higher but less-fluctuated voltage. For further eliminating the fluctuation, the dual-input buck converter with constant resistance control is utilized. The uniform power characteristic, benefiting from the individual control on DQ-phase voltages, is demonstrated under the proposed solution. The uniform power performance is verified on a 1.5-kW prototype with wide-range driving speeds and various practical nonideal conditions. Experimental results, obtained by the DWC simulator, indicate that the output fluctuation factors under the ideal condition are 1.37%, 3.19%, and 4.69% at the driving speeds of 10, 40, and 100 km/h, respectively.

Analysis and Design of Multiphase Receiver With Reduction of Output Fluctuation for EV Dynamic Wireless Charging System

The multiphase receiver for more steady output is proposed in this paper. The conventional power supply rail with multipole such as I-type, S-type, and n-type for dynamic wireless charging (DWC) system has a main drawback: the induced voltage of the double-D coil of receiver has a sinusoidal fluctuation along the driving direction and the fluctuation factor is 1.0. Therefore, the multiphase receivers including two-phase, three-phase, and four-phase receiver are proposed to solve the problem. The fluctuation factor, effective value (rms) of induced voltage and mutual inductance, cost, and loss of different numbers of phase in different connection modes are analyzed and compared. The applicable conditions of different types are given. The structure size of single-phase coil is optimized to achieve larger coupling coefficient. The influence of distance between phases on fluctuation factor and induced voltage (rms) are calculated and the design principle of the distance between phases is determined. Based on above research, design guideline for the multiphase receiver is proposed including the constraints of installation environment and the distribution of different phases. The structure size of single-phase coil and the distance between phases are optimized to improve the coupling coefficient and reduce cost, loss, and voltage level of resonator. Considering the practical application environment, a four-phase receiver of 10-kW DWC system is designed. A prototype system is also established and the analysis and simulation are verified. In the dynamic 10-kW experiment, the fluctuation factor is reduced to 0.146 from 0.3 of two-phase receiver and 1.0 of single-phase receiver.

Study on the optimization of linear induction motor traction system for fast-speed maglev train

Background: The short stator linear induction motor (LIM) is normally used in medium-low speed maglev train.
 The restriction by mounting space on bogie and motor input voltage from the third power supply rail lead that the maximum speed of medium-low speed maglev train can reach no more than 120 km/h.
 Aim: In this paper, by means of the LIM design optimization, improvement of the LIM force characteristic in high speed range, the maximum speed of medium-low speed maglev train can reach 160 km/h.
 Methods: After comparing the LIM theoretical calculation and actual test data, it shows that the new designed LIM is effective.
 Conclusion: Afterwards, by installing the new designed LIMs, the traditional medium-low speed maglev train becomes a fast-speed maglev train, and it has a bright future in transportation applications.

Optimization of the auxiliary stopping area planning in the middle-to-high speed Maglev

Background: The Auxiliary Stopping Area (ASA) is the special section that possesses power supply rail and personnel evacuation facilities, whose quantities and locations in a line are of great significance to reduce construction cost and improve transportation efficiency for the middle-to-high speed maglev.
 Aim: This paper focuses on optimizing the length and location of the ASA for the middle-to-high speed maglev system to improve the robustness of maglev line.
 Methods of the studies: Two evaluation indexes which reflect the ASA restricts on the train operation process was proposed. A model for optimizing the setting of the ASA is constructed, and solved by the genetic algorithm.
 Results: The result of numerical examples shows that the proposed method can effectively improve the performances of the ASA.
 Conclusion: This paper proposed two indexes to reflect the impact of station settings on train operations, which provides a method to optimize the ASA from qualitative optimization to quantitative optimization.

A Novel Magnetic Coupling Mechanism for Dynamic Wireless Charging System for Electric Vehicles

A novel magnetic coupling mechanism with steady output and low cost is proposed in this paper. It is composed of n-type power supply rail and dual-phase coil receiver. The conventional I-type power supply rail has advantages of narrow width, large lateral tolerance, and low electromagnetic field (EMF) radiation which are suitable for dynamic wireless charging. The double-D coil is used as the receiver which is also seen as a single-phase coil receiver. However, the induced voltage of the receiver has a sinusoidal variation with large fluctuation and has zero point along driving direction. The dual-phase coil receiver is proposed to solve this issue and enhance the output power simultaneously. Compared with the I-type power supply rail, the n-type power supply rail is proposed to improve the utilization of the magnetic core and reduce the construction cost, which is crucial for commercialization of dynamic wireless charging of electric vehicles in the future. The advantages of I-type are also preserved. The enhanced output power of dual-phase coil receiver is verified by circuit analysis. We focus on the influence of the structure size by finite element analysis simulation and the design method of structural parameters is proposed to achieve larger lateral tolerance, greater coupling performance, and lower cost. The structure size is optimized and the analyses are verified by a 10 kW prototype system. The fluctuation of induce voltage has been reduced from 100% to 30%. When the lateral displacement of the receiver is 30 cm at airgap of 20 cm, induced voltage drops by only 30%. The EMF is also measured to ensure safety on the environment.