一种开关电容型直流变换器的系统研究与设计

本文利用状态空间方程法对一种开关电容型直流变换器系统进行了稳态和动态特性的研究,该直流变换器采用了具有分段转换系数的多级开关电容电荷泵结构.根据研究结果提出系统在控制方法选择(电流控制和脉冲频率调制)和频率补偿方面的优化办法.基于这些优化办法,本文给出一种高效率、低纹波和低成本的开关电容型直流变换器的系统与电路设计,系统的晶体管级仿真结果达到目前便携式电子产品对电源管理芯片的要求.     

A variable step-down conversion ratio switched capacitor DC-DC converter for energy harvesting systems working in intermittent mode

Energy harvesting systems stimulate the development of power management for low power consumption applications. Improving the converter efficiency of power management circuits has become a significant issue in energy harvesting system design. This paper presents a variable step-down conversion ratio switched capacitor (SC)DC-DC converter to advance the converter efficiency of charge on the stored capacitor in a wireless monitoring system of orthopedic implants. The converter is designed to work at 1 MHz switching frequency and achieves 15 to 2 V conversion. Measurement results show that the converter efficiency can reach 4:2% including all circuit power consumption, which is much higher than previous work.     

GaAs switched capacitor DC-to-DC converter

A switched capacitor DC-to-DC negative converter fabricated in GaAs MESFET technology is introduced in this paper. The converter has an oscillator that runs at 250 kHz, and requires two external capacitors, 0.1 and 1 μF. The converter runs off a wide range of supply voltage, 2 to 10 V, and has a typical output impedance of 75 Ω. A typical open circuit voltage conversion efficiency of 99.6% is achieved. The circuit can be integrated with other GaAs circuits to provide an on-chip negative supply. Measured, simulated and analytical results are introduced in this paper     

CMOS RF switched capacitor bandpass filter tuned by ring VCO

A new RF switched capacitor bandpass filter and its command circuit made up of a ring voltage controlled oscillator with ‘XOR’ gates are proposed. Implemented in a standard CMOS technology, this circuit is intended to be used in a subset of professional mobile phone applications [380–520 MHz]. Experiments carried out on a prototype show a tunable center frequency range of 260 MHz [240–500 MHz], with a quality factor that can be as high as 300.     

一个用于能量攫取系统的间歇式可调降压开关电容直流转换器

Energy harvesting systems stimulate the development of power management for low power consumption applications. Improving the converter efficiency of power management circuits has become a significant issue in energy harvesting system design. This paper presents a variable step-down conversion ratio switched capacitor （SC） DC-DC converter to advance the converter efficiency of charge on the stored capacitor in a wireless monitoring system of orthopedic implants. The converter is designed to work at 1 MHz switching frequency and achieves 15 to 2 V conversion. Measurement results show that the converter efficiency can reach 42% including all circuit power consumption, which is much higher than previous work.     

基于模糊PI的复合电源双向DC-DC变换器研究

针对电动汽车复合电源中基于传统PI的双重移相控制双有源桥DC-DC变换器在负载和输入电压出现扰动时存在动态响应速度慢和超调量大的缺陷,通过有机结合传统PI和模糊逻辑控制,提出基于模糊PI的双重移相控制策略。首先分析双重移相控制下变换器的具体工作过程和功率特性,然后阐述基于模糊PI的双重移相控制实现方式,并详细说明模糊PI控制器的设计方法。最后通过实验论证所提出的控制策略可以有效提高变换器的动态响应速度和鲁棒性,减小输出电压波动。     

高增益DC-DC变换器在光伏系统中的应用研究

以光伏、燃料电池为代表的新能源产业正逐渐兴起,通过高升压的DC-DC变换器将光伏输出电压提升到常规母线直流电压,用来保证正常的并网逆变,但由于其输出电压等级较低,很难达到应用场合所需的电压要求。为了克服这种缺陷,主要介绍目前光伏发电行业不同应用场合下的高增益直流变换器拓扑,同时对高增益变换器进行分类。把几种高增益直流变换器的拓扑进行总结,并分析其工作原理以及优缺点,指出未来直流变换器拓扑的发展趋势和所面临的挑战。     

Microelectronic switched capacitor filters

An explanation of what switched-capacitor (SC) filters are and how they work is given. Attention is focused on low-sensitivity SC filters, which can be developed from a general passive ladder where the branches are arbitrary impedances. The equations that describe the filter components are reviewed, and the characteristics of these low-sensitivity filters are outlined. Applications of the filters in telecommunications are discussed     

Design,fabrication and characterization of miniature RF MEMS switched capacitor based phase shifter

This paper aims to present in detail the design, fabrication and the various characterization techniques adopted in realizing a novel miniature-size switched capacitor based phase shifter. The work strives to provide an all-round development of a DMTL (Distributed MEMS Transmission Line) based phase shifting unit yielding an overall phase shift of 15° at a frequency of 15 GHz. The RF MEMS (Radio Frequency Micro Electro Mechanical Systems) Switched Capacitor based phase shifter has highly miniaturized dimensions, and is capable of solving many limitations to which the conventional Switched Capacitors are mostly susceptible. This miniature RF MEMS switched capacitor actuates at a low actuation voltage of 12 V, exhibits a fundamental frequency of vibration as high as 1.468 MHz and a switching time of 1.4 µs which is an improvement over the other reported designs. Various characterization results seem to validate the simulations.     

Bidirectional phase-shifted DC-DC converter

A novel ZVS phase-shifted DC-DC converter is proposed. The converter operates at a constant switching frequency and the voltage conversion ratio is regulated by phase-shift control. It has bidirectional power flow capability and synchronous rectification, hence the on-state voltage drop of the devices is small. This is an ideal candidate for electric vehicles (EVs)     

Fuel cell power system and high power DC-DC converter

This paper discusses the principle and electrical characteristics of the fuel cell, designs an innovative hybrid power system, and proposes a new DC/DC converter scheme to combine the fuel cell with the storage system. An effective converter scheme for the fuel cell is obtained by analyzing the high efficient topology as well as the phase shifted pulse-width modulation. Through comparing several different control modes of converters, a 75-kW prototype system is constructed, moreover, which steady-state operating characteristics are illustrated and discussed in detail. At last, experimental results are also shown to verify the proposed scheme.     

一种用于RF MEMS移相器及开关可变电容的复合微桥膜结构

提出了一种基于微机械工艺的新型复合微桥膜结构 ,由低应力SiN/SiO2 (0 .5 μm/5 0nm )及Cr/Au(30nm/1μm)构成。相应的工艺流程较为简单。对影响其特性的因素进行了理论分析 ,并提出了 3种桥膜的平面结构 ;利用静电 /力耦合有限元法分析了各种结构的静电驱动特性以及各阶模态 ,结果得到了令人满意的驱动和机械性能 ;通过有限元高频仿真软件对桥膜结构与共面波导形成的可调电容结构进行了分析 ,结果表明其具有良好的射频 /微波性能。该桥膜结构适用于RFMEMS开关、移相器及开关式可调电容和滤波器等     

一种用于RF MEMS移相器及开关可变电容的复合微桥膜结构

提出了一种基于微机械工艺的新型复合微桥膜结构，由低应力SiN／SiO2(0.5μm／50nm)及Cr／Au(30nm／1μm)构成。相应的工艺流程较为简单。对影响其特性的因素进行了理论分析，并提出了3种桥膜的平面结构；利用静电／力耦合有限元法分析了各种结构的静电驱动特性以及各阶模态，结果得到了令人满意的驱动和机械性能；通过有限元高频仿真软件对桥膜结构与共面波导形成的可调电容结构进行了分析，结果表明其具有良好的射频／微波性能。该桥膜结构适用于RF MEMS开关、移相器及开关式可调电容和滤波器等。     

Parasitic compensated switched capacitor circuits

A parasitic-insensitive switched capacitor circuit is presented which can functionally replace the `toggle-switched? capacitor. Its properties are established via an inverting integrator application. A related parasitic-insensitive realisation is also shown for a noninverting integrator, which can provide a 3/2 clock period transmission delay.     

Micropower switched capacitor biquadratic cell

The implementation of the double correlated sampling noise reduction technique in conventional strays-insensitive switched capacitor biquad building blocks is described. The function is performed by an offset cancellation circuit which is incorporated into the structure without the use of any additional capacitor, only minor modifications in the switching topology, and one supplementary clock phase. Consequently, a significant reduction of the low-frequency (1/f) noise is made possible and the usual differential amplifiers may be replaced by simple inverting amplifiers operated in class AB, featuring high-speed, low-quiescent power dissipation and low noise. An experimental micropower SC biquadratic filter section designed for `leapfrog' or `follow-the-leader feedback' structures has been developed using high gain (>80 dB) CMOS push/pull inverting amplifiers together with a three-phase clocking sequence. The integrated circuit, implemented in a low-voltage Si-gate CMOS process, achieves excellent accuracy and less than 5 /spl mu/W power dissipation with a 32 kHz sampling rate and /spl plusmn/1.5 V supplies; dynamic range is 66 dB.     

An electrically-programmable switched capacitor filter

Techniques are presented for the design of a second-order switched capacitor filter which has its frequency response parameters programmed by the application of digital control signals. Two different types of weighted capacitor arrays are used to achieve programmability in the center frequency, peak gain, and selectivity. Experimental results are given for an integrated NMOS version with eight logarithmically-spaced center frequencies programmed by a 3 bit digital word, and 64 Q and gain values programmed by two 6 bit words. The filter is designed so that binary changes in the sampling frequency provide new sets of center frequencies which smoothly continue the logarithmic progression. Since the response depends on monolithic MOS capacitor ratios, the accuracy and reproducibility inherent in the switched capacitor approach are retained.     

MOS switched capacitor ladder filters

A new technique for designing precision, fully integrated, high-order filters using standard MOS technology is described. Switched capacitor integrators have been used to realize long time constants in small areas, and by interconnecting these integrators in a `leapfrog' configuration, monolithic high-order filters have been implemented with transfer functions that are very insensitive to component variations. Experimental results are presented for an NMOS fifth-order Chebyshev low-pass ladder filter with 0.1-dB passband ripple, a cutoff frequency of 3.4 kHz when clocked at 128 kHz, and a dynamic range of 83 dB. An efficient method for implementing transmission zeros is also presented, along with a complete design example, and additional experimental results for a third-order elliptic low-pass ladder filter which achieved 90-dB dynamic range, with a total power dissipation of 18 mW in a die area of 4400 mil/SUP 2/.     

A single-switch flyback-current-fed DC-DC converter

This work presents a novel DC-DC converter, whose significant advantages are the single power switch, single-input inductor, purely capacitive output filter, isolation, low current ripple through the output capacitor, and operation at constant frequency in a conventional pulse-width-modulation scheme. The new converter operates over a wide input-voltage range and can be employed in power factor correction and multiple-output power supplies. Theoretical analysis is presented along with experimental results taken from a laboratory prototype rated at 300 W/50 kHz     

A new ZVT-ZCT-PWM DC-DC converter

In this paper, a new active snubber cell is proposed to contrive a new family of pulse width modulated (PWM) converters. This snubber cell provides zero voltage transition (ZVT) turn on and zero current transition (ZCT) turn off together for the main switch of a converter. Also, the snubber cell is implemented by using only one quasi resonant circuit without an important increase in the cost and complexity of the converter. New ZVT-ZCT-PWM converter equipped with the proposed snubber cell provides most the desirable features of both ZVT and ZCT converters presented previously, and overcomes most the drawbacks of these converters. Subsequently, the new converter can operate with soft switching successfully at very wide line and load ranges and at considerably high frequencies. Moreover, all semiconductor devices operate under soft switching, the main devices do not have any additional voltage and current stresses, and the stresses on the auxiliary devices are at low levels. Also, the new converter has a simple structure, low cost and ease of control. In this study, a detailed steady state analysis of the new converter is presented, and this theoretical analysis is verified exactly by a prototype of a 1-kW and 100-kHz boost converter.