Improved Accuracy Area Efficient Hybrid CMOS/GaN DC-DC Buck Converter for High Step-down Ratio Applications PDF Download

Author: Omkar Joshi
Publisher:
ISBN:
Category : DC-to-DC converters
Languages : en
Pages : 82

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Book Description
Point of Load (POL) DC-DC converters are increasingly used in space applications, data centres, electric vehicles, portable computers and devices and medical electronics. Heavy computing and processing capabilities of the modern devices have ushered the use of higher battery supply voltage to increase power storage. The need to address this consumer experience driven requirement has propelled the evolution of the next generation of small form-factor power converters which can operate with higher step down ratios while supplying heavy continuous load currents without sacrificing efficiency. Constant On-Time (COT) converter topology is capable of achieving stable operation at high conversion ratio with minimum off-chip components and small silicon area. This work proposes a Constant On-Time buck dc-dc converter for a wide dynamic input range and load currents from 100mA to 10A. Accuracy of this ripple based converter is improved by a unique voltage positioning technique which modulates the reference voltage to lower the average ripple profile close to the nominal output. Adaptive On-time block features a transient enhancement scheme to assist in faster voltage droop recovery when the output voltage dips below a defined threshold. UtilizingGallium Nitride (GaN) power switches enable the proposed converter to achieve very high efficiency while using smaller size inductor-capacitor (LC) power-stage. Use of novel Superjunction devices with higher drain-source blocking voltage simplifies the complex driver design and enables faster frequency of operation. It allows 1.8VComplementary Metal-Oxide Semiconductor (CMOS) devices to effectively drive GaNpower FETs which require 5V gate signal swing. The presented controller circuit uses internal ripple generation which reduces reliance on output cap equivalent series resistance (ESR) for loop stability and facilitates ripples reduction at the output. The ripple generation network is designed to provide ai optimally stable performance while maintaining load regulation and line regulation accuracy withing specified margin. The chip with ts external Power FET package is proposed to be integrated on a printed circuit board for testing. The designed power converter is expected to operate under 200 MRad of a total ionising dose of radiation enabling it to function within large hadron collider at CERN and space satellite and probe missions.

Author: Mike Wens
Publisher: Springer Science & Business Media
ISBN: 940071436X
Category : Technology & Engineering
Languages : en
Pages : 316

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Book Description
CMOS DC-DC Converters aims to provide a comprehensive dissertation on the matter of monolithic inductive Direct-Current to Direct-Current (DC-DC) converters. For this purpose seven chapters are defined which will allow the designer to gain specific knowledge on the design and implementation of monolithic inductive DC-DC converters, starting from the very basics.

Author: Weitao Li
Publisher: Springer
ISBN: 3319620126
Category : Technology & Engineering
Languages : en
Pages : 181

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Book Description
This book is a step-by-step tutorial on how to design a low-power, high-resolution (not less than 12 bit), and high-speed (not less than 200 MSps) integrated CMOS analog-to-digital (AD) converter, to respond to the challenge from the rapid growth of IoT. The discussion includes design techniques on both the system level and the circuit block level. In the architecture level, the power-efficient pipelined AD converter, the hybrid AD converter and the time-interleaved AD converter are described. In the circuit block level, the reference voltage buffer, the opamp, the comparator, and the calibration are presented. Readers designing low-power and high-performance AD converters won’t want to miss this invaluable reference. Provides an in-depth introduction to the newest design techniques for the power-efficient, high-resolution (not less than 12 bit), and high-speed (not less than 200 MSps) AD converter; Presents three types of power-efficient architectures of the high-resolution and high-speed AD converter; Discusses the relevant circuit blocks (i.e., the reference voltage buffer, the opamp, and the comparator) in two aspects, relaxing the requirements and improving the performance.

Author: Weimin Zhang
Publisher:
ISBN:
Category : DC-to-DC converters
Languages : en
Pages : 192

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Book Description
The ever increasing demands in the energy conversion market propel power converters towards high efficiency and high power density. With fast development of data processing capability in the data center, the server will include more processors, memories, chipsets and hard drives than ever, which requires more efficient and compact power converters. Meanwhile, the energy-efficient and power-dense converters for the electric vehicle also result in longer driving range as well as more passengers and cargo capacities. DC-DC converters are indispensable power stages for both applications. In order to address the efficiency and density requirements of the DC-DC converters in these applications, several related research topics are discussed in this dissertation. For the DC-DC converter in the data center application, a LLC resonant converter based on the newly emerged GaN devices is developed to improve the efficiency over the traditional Si-based converter. The relationship between the critical device parameters and converter loss is established. A new perspective of extra winding loss due to the asymmetrical primary and secondary side current in LLC resonant converter is proposed. The extra winding loss is related to the critical device parameters as well. The GaN device benefits on device loss and transformer winding loss is analyzed. An improved LLC resonant converter design method considering the device loss and transformer winding loss is proposed. For the DC-DC converter in the electric vehicle application, an integrated DC-DC converter that combines the on-board charger DC-DC converter and drivetrain DC-DC converter is developed . The integrated DC-DC converter is considered to operate in different modes. The existing dual active bridge (DAB) DC-DC converter originally designed for the charger is proposed to operate in the drivetrain mode to improve the efficiency at the light load and high voltage step-up ratio conditions of the traditional drivetrain DC-DC converter. Design method and loss model are proposed for the integrated converter in the drivetrain mode. A scaled-down integrated DC-DC converter prototype is developed to verify the design and loss model.

Author: Peter Renz
Publisher: Springer Nature
ISBN: 3030639444
Category : Technology & Engineering
Languages : en
Pages : 181

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Book Description
This book provides a comprehensive, single-source on resonant switched-capacitor converters. It is written in the style of a handbook, with systematic guidelines, and includes implementation examples. The authors explore integrated hybrid resonant DCDC converters in order to achieve highly compact, energy efficient and cost-effective power management solutions in the growing fields of wearables and internet-of-things applications. They provide an introduction into hybrid converters as a new and promising converter class, which merges capacitive and inductive conversion concepts into one. Coverage ranges from fundamentals to implementation details, including topics such as power stage design, gate drive schemes, different control mechanisms for resonant operation and integrated passives. Introduces a new, multi-ratio resonant converter architecture, which enables lower switching frequencies and better passive component utilization; Discusses circuit block design for high efficiency of the power stage; Explores implementation details and concepts for integrated passives; Derives models, implements and compares to each other different control mechanisms.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
DC to DC step-down applications with high input voltage and high voltage conversion ratio operational requirements, such as photovoltaic battery chargers, are subject to high conduction losses, high switching losses and substantial reverse-recovery losses when minority carrier principle diodes are used. The recent introduction of silicon carbide diodes with high breakdown voltages has made possible the elimination of reverse-recovery losses at high voltage levels and as such has sparked interest in their use due to the potential efficiency improvements. This report presents the results of a comprehensive analysis on the use of silicon carbide diodes and their counterparts, ultrafast silicon diodes, in conventional buck converters and isolated current-fed buck converters in high input voltage and high voltage conversion ratio step-down applications. The analysis illustrates both theoretically, with the use of steady-state average models, and experimentally the substantial efficiency benefits of the use of reverse-recovery free silicon carbide diodes in the conventional buck converter and the small but significant improvement in the efficiency of the isolated current-fed buck converter. The improvements of the conventional buck converter paired with silicon carbide diodes are shown to be significant enough to grant the variant the most efficient position for power levels below 1 kW. In addition, the four variants are categorized based on their cost and performance; therefore, providing engineers with a convenient guide to aid their selection of the appropriate converter depending on the operational requirements.

Author: Krushal S. Shah
Publisher:
ISBN:
Category : DC-to-DC converters
Languages : en
Pages : 72

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Book Description
The power generated by renewable sources such as solar photo-voltaic (PV) arrays and wind turbines is time varying and unpredictable. In order to minimize the wastage of power obtained from such sources, there is a great need of efficient power converters which are compact and can effectively manage power in Smart Grid applications. The design of such power converters would require the use of new semiconductor materials, novel device structures, improved switching and control circuits, and advanced packaging technologies. Wide bandgap materials are promising for RF/microwave and power switching electronics. Among these materials, III-V Nitrides - especially Gallium Nitride (GaN), and Silicon Carbide (SiC) are heavily investigated by industry because of their superior electrical and thermal properties, and improved radiation hardness compared to the standard semiconductor material -silicon. A smart DC microgrid suitable for high-penetration in commercial applications and that efficiently utilizes energy available from distributed, renewable generators is described. GaN HEMTs based converters should be incorporated in the DC microgrid. It iv is shown that the proposed DC power distribution system can produce savings in excess of 10-15% over the current approach that uses inverters. Performance evaluation between silicon MOSFET and GaN HEMT is presented for chip-scale and maximum peak power tracking DC-DC power converter applications. The current circuit model available for GaN HEMTs does not converge for converter topology. Thus circuit calculations are based on improved circuit model for the FET with accurate description of capacitances and thermal on-resistance. It is shown that GaN power HEMTs used in a synchronous buck converter topology (for a 19/1.2VDC, 7.2W) can potentially lead to nearly 77 % power conversion efficiency at 25°C when switched at 5 MHz. However, results show that the current formulation for loss calculation in the topology described is erroneous and so there is a need of new loss formulation and device selection criteria based on circuit dynamics and device parameters. Similarly simulations were carried out for a DC-DC boost converter topology (200/380VDC, 10kW) and it has been shown to have 93 % power conversion efficiency at 25°C when switched at 1 MHz. But using new semiconductors materials like GaN HEMT and SiC in this case causes high dv/dt stress on switch and diode during switching which may cause failure of device.

Author: Alex Lidow
Publisher: John Wiley & Sons
ISBN: 1119594421
Category : Science
Languages : en
Pages : 470

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Book Description
An up-to-date, practical guide on upgrading from silicon to GaN, and how to use GaN transistors in power conversion systems design This updated, third edition of a popular book on GaN transistors for efficient power conversion has been substantially expanded to keep students and practicing power conversion engineers ahead of the learning curve in GaN technology advancements. Acknowledging that GaN transistors are not one-to-one replacements for the current MOSFET technology, this book serves as a practical guide for understanding basic GaN transistor construction, characteristics, and applications. Included are discussions on the fundamental physics of these power semiconductors, layout, and other circuit design considerations, as well as specific application examples demonstrating design techniques when employing GaN devices. GaN Transistors for Efficient Power Conversion, 3rd Edition brings key updates to the chapters of Driving GaN Transistors; Modeling, Simulation, and Measurement of GaN Transistors; DC-DC Power Conversion; Envelope Tracking; and Highly Resonant Wireless Energy Transfer. It also offers new chapters on Thermal Management, Multilevel Converters, and Lidar, and revises many others throughout. Written by leaders in the power semiconductor field and industry pioneers in GaN power transistor technology and applications Updated with 35% new material, including three new chapters on Thermal Management, Multilevel Converters, Wireless Power, and Lidar Features practical guidance on formulating specific circuit designs when constructing power conversion systems using GaN transistors A valuable resource for professional engineers, systems designers, and electrical engineering students who need to fully understand the state-of-the-art GaN Transistors for Efficient Power Conversion, 3rd Edition is an essential learning tool and reference guide that enables power conversion engineers to design energy-efficient, smaller, and more cost-effective products using GaN transistors.

Author: Venkata Raghuram Namburi
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
Electric vehicles with autonomous-driving or driver-assistance features have introduced computationally intensive and safety-critical integrated circuit modules. A complementary 48-V network has been proposed to enable more efficient power distribution. An efficient high-conversion-ratio architecture is necessary to interconnect the 48-V bus to the low core-voltages (0.8 V - 1.2 V). The focus of this thesis is the design of a 48-V-to-1-V direct power conversion system, which enables efficient low-voltage, high-current power delivery, near-optimal transient response, and fault-isolation. The 6-to-1 hybrid Dickson switched-capacitor topology satisfies these requirements, particularly fault-isolation, without additional components. A selection methodology is utilized to obtain an optimized set of switches with the minimum necessary voltage rating to support fault-isolation and maximize efficiency. An output-capacitor ripple-current based control strategy, featuring inherent flying-capacitor voltage balancing, near deviation-optimal dynamic behavior, and reduced flying-capacitor voltage drain during transients is presented. A prototype is built to verify and demonstrate the claimed properties.

Author: Yingping Chen
Publisher:
ISBN:
Category : Electromagnetic interference
Languages : en
Pages : 0

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Book Description
DC-DC power conversion circuits improve the switching frequency consistently over the past five decades, pursuing better dynamic response and higher power density. To empower such a trend, silicon power transistors have been advancing continuously. However, they are approaching the theoretical limit of performance, slowing down the developing pace of power electronics. With superior switching characteristic, gallium nitride (GaN) high-electron-mobility transistor (HEMT) rapidly emerged, pushing the operating speed of DC-DC power circuits to a record high level. GaN technology is thus recognized as a promising candidate to enable the next-generation switching power conversion. However, it still faces formidable challenges before the industry-wide adoption, including unique reliability issues, considerable electromagnetic interference (EMI) emissions and intensified power design trade-offs. This dissertation delivers key innovations in power stage, gate driver and control scheme, intending to conquer these challenges. To improve the reliability of GaN power stage, an online condition monitoring is developed to prognose the current-collapse (or i-collapse) effect in GaN HEMT, sensing its dynamic onresistance as aging precursor. A gate leakage inspired junction temperature TJ sensor is integrated to determine the TJ of GaN HEMT, facilitating the calibration of temperature effect on the dynamic on-resistance. As the benefit, TJ-independent online condition monitoring is accomplished, significantly improving the monitoring accuracy. Further, to enhance the system longevity, a proactive temperature frequency scaling scheme is designed to modulate the operating speed according to the thermal stress and power conditions, thereby extending the GaN lifetime while minimizing the impact on the system performance of the converter. To reduce the conducted EMI noise, an adaptive strength gate driving scheme is developed for GaN HEMT. By modulating the driving strength at the start point of Miller Plateau during the switching transitions, it achieves an independent control of low di/dt and high dv/dt. Thus, the conducted EMI noise, mainly caused by di/dt, is reduced, while the switching power loss overhead is minimized. By such a means, the classic design trade-off between EMI noise and power efficiency is effectively balanced. To facilitate such an active control, an emulated Miller Plateau tracking scheme is proposed to identify the critical di/dt and dv/dt instants, which are susceptible to load current and power input voltage conditions. These proposed techniques are incorporated in a GaN-based buck converter for verification. Moreover, a continuous random spread-spectrum-modulation (C-RSSM) technique is utilized to scatter the EMI spectra evenly and continuously, attenuating the EMI further. For demonstration, the proposed C-RSSM scheme is applied to a GaN-based buck converter with peak current mode control. In the meantime, a one-cycle on-time rebalancing scheme is designed to overcome the crossover frequency limit existing in the conventional PWM control, thereby stabilizing the duty ratio under frequency modulation. Beneficially, the output jittering effect induced by RSSM is removed, balancing the trade-off between EMI and output regulation.