Switched-capacitor Voltage Multiplier Research Articles

A novel multi-input medium-gain DC-DC boost converter with soft-switching performance

This paper proposes a new non-isolated dual-input zero-voltage switching (ZVS) dc-dc boost converter with medium voltage gain. Two input ports of the converter are current-fed and suitable for a unidirectional dc power source, and a chargeable dc energy storage. The proposed converter basic circuit composed of three cascaded power switches, which at their connection points join to the converter three inductors and a switched capacitor voltage multiplier (VM) cell is accompanied. Using this VM cell the converter voltage gain achieves two times of that in the conventional boost converter and also half voltage stress across the power switches. Through the converter two input inductors powers from a unidirectional source (like PV) and a chargeable battery source can be accepted. Taking a triangular resonant current at the switching frequency, the converter third inductor aids to reach ZVS for the power switches. The converter power switches turn-on with ZVS and the power diodes stop conducting with ZCS in all operation conditions. As a result, low switching power losses, reduced reverse recovery issue, and high efficiency are accessible especially for higher input and output powers. The converter power switches are switched in PWM manner with two individual duty ratios, allowing to regulate the output voltage and control the extracted power from the input unidirectional port. The proposed circuit has been analyzed in detail to find its different operating modes, determine its capacitor currents, estimate its power losses components and design its control system. Behavior of the proposed system is also examined by a low-power laboratory prototype tested under four different practical operation conditions. The proposed converter benefits from simple and compact structure, current-fed input ports, low number of power switches and magnetic elements, low voltage stress across the power switches, medium voltage gain and high efficiency.

New Dual-Source High-Gain ZVS DC-DC Converter for Integrating Renewable Power Source and Battery Storage

A new soft-switching high-gain two-source dc-dc boost converter is proposed here. The proposed converter provides two bidirectional and unidirectional input ports, handling the energies of a battery storage and a renewable power source, respectively, to supply a resistive load through a switched-capacitor (SC) voltage multiplier. As a result, three power switches, four power diodes, two inductors and four capacitors are used in the converter structure. The ZVS of all power switches is realized without any auxiliary circuit and in whole power ranges of the converter input sources and the output load. The converter power MOSFETs are switched in PWM manner with two individual duty ratios, allowing to regulate the output voltage and control the power coming from the input unidirectional port. Depending on the converter duty ratios, its basic operation principle is analyzed in two different operation cases. The behavior of the proposed converter is analytically investigated, and a low-power laboratory prototype is built to evaluate the converter performance in different operation conditions. The proposed converter benefits from simple and compact structure, minimum number of power switches and magnetic elements, reduced voltage stress across the power semiconductor devices, high voltage gain and high efficiency.

A 6-to-7.5-GHz 54-fsrms Jitter Type-II Reference-Sampling PLL Featuring a Gain-Boosting Phase Detector for In-Band Phase-Noise Reduction

This paper presents a type-II reference-sampling (RS) phase-locked loop (PLL) exploiting a novel gain-boosting reference-sampling phase detector (RSPD) to reduce the in-band phase noise and RMS jitter. The proposed gain-boosting RSPD converts the phase error to the voltage error and utilizes a passive switched-capacitor voltage multiplier to amplify the sampled voltage error, which effectively increases the gain of the RSPD. The boosted RSPD gain helps suppress the phase noise contributed from the gm cell. To prevent the transistors in the gain-boosting RSPD and gm cell from breakdown, the gain-boosting function is only activated during the locked state when the phase and voltage errors are small. The switching between the gain-boosting and normal modes is realized automatically by monitoring the sampled voltage and comparing it with a pre-defined threshold window. Fabricated in 65-nm CMOS, the type-II RS-PLL measures an RMS jitter of 54 fs at 6.75 GHz and consumes 7.1 mW, corresponding to a jitter figure-of-merit (FoMjitter) of −256.8 dB. The measured reference spur is −62.6 dBc, and the active area is 0.25 mm2.

Input Current Ripple Reduction in a Step-Up DC–DC Switched-Capacitor Switched-Inductor Converter

This paper presents research results related to the concept of a high-voltage-gain DC-DC converter with a low input current ripple. In the proposed topology, a low-volume DC-DC switch-mode boost converter operates in parallel with a switched-capacitor voltage multiplier (SCVM). The overall converter achieves a four-fold voltage gain, but the voltage stress of the transistor and the diode of the boost converter is only half of the output voltage. This is achieved by applying the specific topology of the proposed converter. Furthermore, the boost part uses a low-volume choke as it operates in the discontinuous conduction mode (DCM). The parallel operation of the boost converter and the SCVM decreases the current stress in some components of the multiplier. This paper presents a concept of the hybrid converter, an analytical model for the selection of components and switching parameters, an efficiency model, and the verification of the converter operation through simulation tests and experiments.

A Fully Integrated 10-V Pulse Driver Using Multiband Pulse-Frequency Modulation in 65-nm CMOS

This brief describes a fully integrated 10-V pulse driver. It comprises a four-stage switched-capacitor voltage multiplier (SCVM) and a dedicated high-voltage output driver (HVOD) with multiband pulse-frequency modulation (MPFM) to generate efficiently 10 V regulated output pulses. Specifically, an analog/digital hybrid-controlled current-starved ring oscillator (HCRO) modulates the switching frequencies at distinct bands to regulate the high-voltage (HV) supply for the HVOD, while enabling fast output transitions with an improved driving efficiency. Prototyped in 65-nm bulk CMOS, the driver demonstrates 10-V pulse generations over a 0.1-to-1-MHz range for a 15 pF//50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{k}\Omega $ </tex-math></inline-formula> load. With the proposed MPFM, this work measures an overall driving efficiency of up to 19.9%, corresponding to a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 1.6\times $ </tex-math></inline-formula> improvement over prior arts. The measured output rise time of 119 ns is also ~25% faster when compared with using the conventional pulse-frequency modulation (PFM) scheme.

Single-Phase Hybrid Boost AC–DC Converters With Switched-Capacitor Cells and Reduced Switch Count

This article proposes new configurations of hybrid boost rectifier topologies with switched-capacitor cells to reduce the number of switches. The proposed converters use switched-capacitor voltage multipliers to increase the voltage gain of the conventional boost rectifier and reduce the voltage stress across the switches. The new topologies are able to achieve output voltage regulation and a near unity input power factor. The proposed integration of the boost switching cell and the ladder cell reduces the number of semiconductor devices of the conventional hybrid boost rectifier. A generalized topology is presented and two variations of the topology are studied within greater depth. The theoretical analysis of these topologies is performed and evaluated experimentally through a 1-kW prototype with 220 V ac input and 800 V dc output voltages. The converter presented a maximum efficiency of around 97.9% and input power factor above 0.99.

A Three-Phase Constant Common-Mode Voltage Inverter With Triple Voltage Boost for Transformerless Photovoltaic System

This paper introduces a new three-phase two-level inverter based on the switched-capacitor voltage multiplier. By adding a voltage multiplier network at the DC side of the traditional three-phase inverter topology, the DC-link voltage of the introduced inverter is stepped up to triple of the input voltage. Compared to the existing solutions, the common-mode voltage of the introduced topology is kept constant. Moreover, the voltage stress across additional semiconductor components is the same as one-third of DC-link voltage. Operating principles, mathematical analysis, circuit analysis, and pulse-width modulation (PWM) method based on the Boolean logic function for introduced inverter are presented. A comparison of the introduced inverter with other inverter topologies is also reported. The simulation results are shown to verify the introduced three-phase triple voltage boost inverter. Besides that, a laboratory-built prototype is developed based on a DSP F280049C microcontroller and the corresponding experimental tests are provided to prove the introduced inverter.

Hybrid Operational High Step-Up DC–DC Converter

High step-up DC–DC voltage converters are widely employed in uninterruptible power supplies and photovoltaic systems. The voltage levels of batteries and photovoltaic panels are, usually, low when compared with the grid-connected inverter requirements. The employment of several PV panels or batteries associated in series, directly connected to the inverter, simplifies the system but at the expense of the cost increase and of a smaller solar lighting efficiency/utilization. Several high step-up DC–DC voltage conversions are presented in the technical literature and include the basic boost converter and its derivations such as cascade, quadratic and interleaved, and voltage multipliers based on Cockcroft–Walton, switched capacitors and hybrid converters. This work presents a hybrid converter based on the boost and the switched-capacitor voltage multiplier. Its features are a low energy processing, robustness and balanced cell voltages. Comparative analysis involving the proposal and existent solutions is carried out. The research is supported by simulation essays carried out with PSpice software and preliminary experimental verification.

Fully Integrated High Voltage Pulse Driver Using Switched-Capacitor Voltage Multiplier and Synchronous Charge Compensation in 65-nm CMOS

This brief presents a high efficiency fully integrated high-voltage (HV) pulse driver in standard CMOS. Powered by a standard I/O DC voltage of 2.5 V, the proposed system employs an optimized 4-stage cross-coupled switched-capacitor voltage multiplier (SCVM) together with an on-chip HV output driver to generate HV pulses of >10 V. We propose an area-efficient HV output driver stage to reach up to 12% total active area reduction when compared with the conventional implementation while maintaining the low static power characteristics. We also present a synchronous charge compensation (SQC) technique to alleviate the loading-dependent signal distortion through reducing the HV rail voltage droop and improving the HV pulse settling time during the driver output transitions. Fabricated in 65-nm bulk CMOS, the chip prototype can successfully generate HV pulses from 250 kHz to 1 MHz with a 15 pF load while ensuring no device breakdown. Measurement results demonstrate a peak SCVM power conversion efficiency (PCE) of 50% and an overall driving efficiency of 12.25%. The chip prototype attains a $\sim 2\times $ faster output pulse transition speed compared with the state-of-the-art.

A Switched-Capacitor DC–DC Converter With Variable Number of Voltage Gains and Fault-Tolerant Operation

This paper presents research results of voltage gain number control methods of a power electronic resonant zero-current switching dc–dc switched-capacitor (SC) voltage multiplier (SCVM) in a topology with fault tolerance capability (FSCVM). The converters operated under the basic switching patterns are constant-voltage-gain dc–dc series-parallel resonant SC converters. However, this paper presents a method for the output voltage regulation by a special switching strategy. A variable voltage gain is made possible by selecting the number of active switching cells, using an appropriate control method. This creates a set of voltage ratio ranges. In addition, the proposed topology and method of control enable a fault-tolerant operation of the FSCVM under various failures of the device. The paper presents an analysis of the concept, simulation results and an experimental verification in a three-cell FSCVM dc–dc resonant boost converter operating at a 200-watt charge. Issues regarding the selection of components related to the problem of inrush currents that can occur during the voltage ratio increase are also analyzed in this paper, and the design for low inrush currents is demonstrated.

A Cost-Effective Resonant Switched-Capacitor DC-DC Boost Converter – Experimental Results and Feasibility Model

Abstract This paper presents the results of experimental research of a resonant switched capacitor voltage multiplier in a cost-effective topology (CESCVM) with a limited number of active switches. In the charging mode of the switched capacitors, the converter utilizes only one active switch and a required number of diodes. Therefore, the cost of the converter is decreased as compared with that of a classical SCVM converter, owing to a lower number of switches and gate driver circuits, as well as a smaller PCB area. Moreover, the CESCVM has simpler control circuits and higher reliability. This paper presents the original experimental results of the operation of the CESCVM converter. A concept of the bootstrap supply of gate drivers of the flying switches is also examined.

Efficiency Analysis of MOSFET-Based Air-Choke Resonant DC–DC Step-Up Switched-Capacitor Voltage Multipliers

This paper presents the investigation results of the efficiency of power electronic resonant zero-current switching dc–dc switched-capacitor voltage multipliers (SCVMs) in three topologies. The analytical model of efficiency shows the impact of the converters’ particular parameters on their properties and gives indications for an adequate design. The impact of the parameters of the semiconductor devices, parasitic resistances, switched capacitance value, number of switching cells, switching frequency, and choke design on the converters’ efficiency is demonstrated. The converters are investigated analytically with the use of computer-based simulations and experimentally as a three-cell MOSFET-based SCVM dc–dc resonant boost converter. The in-depth analysis and the results obtained are some novel contributions to the existing knowledge of switched-capacitor-based power electronic conversion. Moreover, the presented method of analysis can be useful for analyzing other types of SC power converters comprising resonant switching circuits.

A family of high-power multilevel switched capacitor-based resonant DC-DC converters – operational parameters and novel concepts of topologies

Abstract This paper presents the concept of topologies and investigation results of switched-capacitor voltage multipliers designed for application in high power systems. The analyzed family of multilevel converters includes established topologies as well as novel concepts. The application of thyristors as well as the invention of novel concepts of multiplier topologies and appropriate control make it possible to achieve high efficiency, high voltage gain, reliable and simple DC-DC converters for high power systems. Based on analytical models of the SCVMs, the paper presents a discussion of the selection of components and the efficiency of the converters as a function of converted power as well as the voltage range on the input and the output side. The results are supported by computer simulations and demonstrative experimental tests.

Resonant switched capacitor voltage multiplier with interleaving capability

This paper presents a switched capacitor voltage multiplier with resonant-type current between capacitors; these current waveforms are achieved by designing a resonant topology combined with a safe switching strategy. Moreover, the proposed converter provides interleaving capability, soft switching, modular structure and a reduced number of components. These features yield a low cost converter with high voltage gain scalability, reduced input current ripple and limited peak currents between capacitors. Experimental results that corroborate the advantages of the proposed topology are presented.

Innovation of Switched-Capacitor Voltage Multiplier: Part 1: A Brief History

The switched-capacitor (SC) voltage multiplier is becoming one of the most critical IC blocks for energy harvesting in wireless sensor nodes to generate a voltage high enough for microwatt sensing and computing ICs in a nanometer complementary metal?oxide?semiconductor (CMOS) from environmental energy sources such as mechanical vibration, electromagnetic wave, and temperature gradient. However, its origin was a 10 m-scale particle accelerator generating 1 MV back to 1920s. There have been several innovative design techniques to realize integrated SC voltage multipliers since the original one. This article overviews such innovations for the last century and describes how 10 m-scale SC voltage multipliers have been integrated in microwatt ICs and what technical considerations are critical for area- and power-efficient design. It also summarizes how device parameters determine circuit performance such as output voltage current and power efficiency. There have been also several design innovations in switching circuits to enable to work at extremely low voltages. This article shows state of the art for switching circuits for both dc-dc and ac-dc voltage multipliers and their applications as well.

Innovation of Switched-Capacitor Voltage Multiplier: Part 3: State of the Art of Switching Circuits and Applications of Charge Pumps

In Parts 1 [1] and 2 [2] of this series, a brief history of the switched-capacitor voltage multiplier and the fundamentals of the charge pump have been discussed. In this Part 3, the state of the art of switching circuits and applications of charge pumps are reviewed. The threshold voltage of the switching devices degrades the output current and power efficiency, as discussed in [2]. Thus, reducing the effect of the threshold voltage has been challenging for charge pump design especially for low-voltage operation. Let's begin with some state-of-the-art active rectifier designs.

Innovation of Switched-Capacitor Voltage Multiplier: Part 2: Fundamentals of the Charge Pump

In Part 1 of this series [1], a brief history of switched-capacitor voltage multiplier was reviewed starting with Greinacher's voltage doubler in 1914 [2]. It was concluded that the Falke-Dickson [3], [4] parallel voltage multiplier or charge pump was best for integrated circuits where capacitors and switching devices had significant parasitic capacitance [5]. In this Part 2, the structure of integrated switching devices and capacitors is reviewed. An equivalent circuit and power efficiency of the charge pump is discussed in both the ideal and real cases in terms of threshold voltage of switching transistor and parasitic capacitance. Finally, several design optimizations are described.

Transformerless high gain boost converter for low power applications with feedback control

A transformer-less boost converter which provides high voltage gain without utilizing transformer or coupled inductors and extreme duty cycle is proposed in this paper. Also it is able to cancel the ripples in the input current at a preselected duty cycle, without increasing the number of components. The converter combines the features of boost converter and a three switch high voltage converter. At the input side, two inductors are interleaved for cancelling the input current ripple and at the output side switched capacitor voltage multiplier is used to increase the voltage gain. Feedback control is used to make the output voltage constant in spite of variation in the input or load or both i.e. both line and load regulation is accompanied. This proposed converter configuration helps eliminate the input current ripple and provides voltage deregulation for low power applications.

Transformerless high gain boost converter for low power applications with feedback control

A transformer-less boost converter which provides high voltage gain without utilizing transformer or coupled inductors and extreme duty cycle is proposed in this paper. Also it is able to cancel the ripples in the input current at a preselected duty cycle, without increasing the number of components. The converter combines the features of boost converter and a three switch high voltage converter. At the input side, two inductors are interleaved for cancelling the input current ripple and at the output side switched capacitor voltage multiplier is used to increase the voltage gain. Feedback control is used to make the output voltage constant in spite of variation in the input or load or both i.e. both line and load regulation is accompanied. This proposed converter configuration helps eliminate the input current ripple and provides voltage deregulation for low power applications.

Single‐inductor resonant switched capacitor voltage multiplier with safe commutation

This study proposes a resonant switched capacitor voltage multiplier with a novel switching strategy. The proposed implementation provides a high voltage gain in comparison with other traditional approaches, this is achieved by charging every capacitor with the voltage of all previous charged capacitors. A safe commutation procedure is also presented in which switching errors are avoided regardless of variations in the resonant frequency, variations in the resonance frequency may be caused by tolerance in passive components. The converter offers the capability to drain resonant current through all switching devices using a single small inductor, the input current is continuous. A design-oriented analysis of steady-state waveforms is discussed through the study. To validate the proposed approach, experimental results are shown.