Transient processes in a bandpass filter caused by stepwise phase variations

Transient processes at the output of a bandpass filter caused by a stepwise phase variation in the input high-frequency signal are studied in the time domain. A mathematical model of this type of transient processes in the form of a narrowband process is presented. Analytic expressions describing the behavior of the transient process in the time domain are obtained. New features of this type of transient processes are revealed.     

The Influence of the Startup Process of Small Metal-Halide (MH) Lamps on Electronic Ballast Design

In this paper, the authors present the results of an investigation into the starting process of a small wattage metal halide lamp and address the influence of the starting process, at extra- high frequency (>350 kHz), upon the performance of two most commonly used electronic ballast circuit topologies, namely the LCC resonant inverter and LCL resonant inverter. The starting transient processes driven by both ballast systems are captured, analyzed and explained. It has been found that the starting process could affect the operating performance of an LCL ballast and may destroy its power switches in the worst case while a LCC ballast gets the advantage over the LCL ballast for the stability during the transient starting process.     

The analysis of the transient process caused by a jump in the amplitude and phase of a radio pulse at the input of a narrowband linear system

The transient process caused by a jump in the amplitude and phase of a radio pulse in the absence and presence of frequency detuning at the input of a narrowband linear system is analyzed. New general features of this type of a transient process are revealed, and its mathematical model in the form of a narrowband process is presented. Analytic expressions describing the behavior of the process in the time domain are obtained.     

基于最优负载瞬态特性的单相全桥逆变器解耦设计

针对单相全桥工频逆变器设计过程欠缺规范的问题,该文提出了一种以动态设计指标为条件解耦设计主电路滤波参数和控制器参数的公式化分步设计法.以阻性负载跃变量为条件,分析了单相全桥工频逆变器在两种极端情况下的最优负载瞬态响应过程,推导了最优负载瞬态特性关于滤波参数的数学表达式,并给出了表达式适用范围-输出电压跌落量低于10%,且结合逆变器的动态设计指标提出了一种滤波器参数设计方法,再以滑模控制为例,结合动态设计指标给出了一种滑模控制器设计方法.仿真实验结果验证了最优负载瞬态响应过程的存在性,最优负载瞬态特性表达式的正确性和有效性,也验证了解耦设计法的正确性和有效性.该解耦设计法具有良好的理论价值和工程价值.     

A Scalable High-Voltage Output Driver for Low-Voltage CMOS Technologies

A monolithic implementation of series connected MOSFETs for high-voltage switching applications is presented. Using a single low-voltage control signal to trigger the bottom MOSFET in the series stack, a voltage division across parasitic and inserted capacitances in the circuit is used to turn on the entire stack of devices. This voltage division both statically and dynamically safeguards the individual MOSFETs over the entire switching period. Because the output voltage is balanced across each device in the stack for the entire switching period, stress to the oxide and hot-carrier degradation are minimized, even in the event of transient over voltages. This circuit, termed the Stacked MOSFET, is ntimes scalable, allowing for the on-die control of voltages that are ntimes the fabrication processes rated operating voltage. The governing equations for this circuit are derived and reliable operation is demonstrated through simulation and experimental implementation in a 0.35-mum SOI CMOS process. The realized prototype is shown to handle 2times the nominal process operating voltage at a switching frequency of 20 MHz with an input-to-output delay of only 5.5 ns     

Integrated current-mode DC–DC boost converter with high-performance control circuit

In this paper, integrated BiCMOS amplifier and current-sensing circuits are introduced for high-performance DC–DC boost converter. By exploiting the advantage of BiCMOS technology, the high gain amplifier and accurately sensed inductor current are obtained in the feedback control circuit. The proposed current-sensing circuit adopts a current-mirror instead of op-amplifier as a voltage follower so that it would reduce power consumption with a smaller chip-size. Bipolar transistor is also applied in the differential pair and current sources of the error amplifier to obtain a fast transient response. Frequency response shows the amplifier gain with the compensator affects significantly on the stability of the converter. The chip is fabricated in 0.35 µm 2-poly 4-metal BiCMOS process. The measurement shows that the current-sensing circuit can operate with accuracy of higher than 90 % at the frequency from 10 to 200 kHz and the transient time of the error amplifier is controlled within 10 µs. The converter with chip-size of 1 mm² operates at the output voltage of 4.5–9 V with the frequency of 0.01–1 MHz.     

IF Variable Equalizers for FM Microwave Radio Links

The circuit configuration, operational principles, and some test data on three new types of equalizers applicable for use in FM microwave radio links are described. The equalizers are namely of the reflection type, frequency converter type, and AM-PM conversion type. The reflection type delay equalizer permits variation of relative delay time while keeping the absolute delay time constant at the center frequency or permits variation of absolute delay time while keeping the relative delay time constant. The frequency converter type equalizer adopts a principle whereby variation in local frequency (supplied to the frequency converter) facilitates continuous variation of the relative delay time, absolute delay time, and amplitude frequency response. The AM-PM conversion type differential gain equalizer enables equalization of differential gain through the combined use of the AM-PM converter circuit and the delay circuit.     

Improved realization of canonical Chua's circuit with synthetic inductor using current feedback operational amplifiers

In this paper, we report an improved implementation of an inductorless third order autonomous canonical Chua's circuit. The active elements as well as the synthetic inductor employed in this circuit are designed using current feedback operational amplifiers (CFOAs). The reason for employing CFOAs is that they have better features such as high slew rate and high speed of operation, which enable the circuit to operate at higher frequency ranges, when compared to the circuits designed using voltage operational amplifiers. In addition to this, the inclusion of CFOAs provides a buffered output which directly represent a state variable of the system. The Multisim simulations in the time and frequency domains confirm the theoretical estimates of the performance of the proposed circuit at high frequencies. It is also confirmed through hardware experiments.     

A framework for energy and transient power reduction during behavioral synthesis

In battery driven portable applications, the minimization of energy, average power, peak power, and peak power differential are equally important to improve reliability and efficiency. The peak power and the peak power differential drive the transient characteristics of a CMOS circuit. In this paper, we propose a framework for the simultaneous reduction of energy and transient power during behavioral synthesis. A new metric called "cycle power function" (CPF) is defined which captures the transient power characteristics as an equally weighted sum of the normalized mean cycle power and the normalized mean cycle differential power. Minimizing CPF using multiple supply voltages and dynamic frequency clocking under resource constraints results in the reduction of both energy and transient power. Based on the above, we develop a new datapath scheduling algorithm called CPF-scheduler which attempts at power and energy minimization by minimizing the CPF parameter during the scheduling process. The type and number of functional units available become the set of resource constraints for the scheduler. Experimental results indicate that the proposed scheduler achieves significant reductions in terms of power and energy.     

A study of locking phenomena in oscillators

Impression of an external signal upon an oscillator of similar fundamental frequency affects both the instantaneous amplitude and instantaneous frequency. Using the assumption that time constants in the oscillator circuit are small compared to the length of one beat cycle, a differential equation is derived which gives the oscillator phase as a function of time. With the aid of this equation, the transient process of "pull-in" as well as the production of a distorted beat note are described in detail. It is shown that the same equation serves to describe the motion of a pendulum suspended in a viscous fluid inside a rotating container. The whole range of locking phenomena is illustrated with the aid of this simple mechanical model.     

基于小波域的电路信号分析

本文在离散小波变换矩阵表示的基础上,由时域方程直接推导了电阻、电感、电容、变压器等电路元件在小波域的等效电路方程,并将之应用于电路分析中.该方法具有推导简单,且能分析电路时-频特征的特点,较单独的时域或频域分析更适合于暂态和瞬变信号的分析.     

超视距雷达海杂波与干扰信号的多域特征与海杂波检测

针对超视距(OTH)雷达接收信号成分复杂的问题,该文提出基于多域组图的信号分析方法,讨论海杂波、瞬态干扰和射频干扰的多域特征。运用时域、频域、距离域、重复周期和多普勒5域,组合为6种2维矩阵图,提出雷达接收数据的“五域六图”(5D6M)方法。通过五域六图,各种接收信号成分在多个域得以分离,海杂波和干扰在不同域的特征得以体现,清晰展示海杂波的频谱和多普勒谱特性、瞬态干扰的大功率和短时性以及射频干扰的窄带与多普勒特性。基于五域六图的信号特性分析,能够为雷达信号分析与处理提供很好的帮助。该文以海杂波为例,设计了基于频域-多普勒域的海杂波多普勒单元检测的新方法。     

集成的B iCMO S DCöD C 开关电源控制器 输出驱动电器的低功耗设计

为使DC／DC开关电源的功率开关管及时地导通或截止,需要设计专用的输出驱动电路,基于整个开关电源系统低功耗的考虑,开关电源可以采用同步整流的拓扑结构。该拓扑结构需要一个电压自举的输出驱动电路,本文首先提出了一种有自举功能的BiCMOS工艺的输出驱动电路,在此基础上,采用电流源和电流沉串联的方式改进了前面提出的输出驱动电路,通过消除CMOS电路的瞬态短路导通现象,不仅降低了该电路模块的功耗,而且起到了保护的作用,经HSPICE模拟表现,开关电源的输入电压Vin为10V控制器内部电压（VL）为5V,开关频率为200kHz时,改进驱动电路的功耗降低了约11．5％,同时避免了瞬态短路导通现象。     

OFDM系统信道估计算法及其FPGA实现

文章深入分析研究了欧洲数字高清晰度电视地面广播(DVB-T)系统的COFDM调制方案。通过对大量算法的仿真，总结出适用于该方案且易于实现的信道估计算法，结合Matlab、Quartus仿真及工程应用，提出一种基于FPGA的电路设计，并完成了相应的硬件电路。     

High Efficiency Time Redundant Hardened Latch for Reliable Circuit Design

In a modern high density VLSI design, with higher operating frequency and technology scaling, small critical charge in circuit nodes significantly increases susceptibility to radiation induced transient faults. In this paper, we propose a high efficiency hardened latch using the undesired delay of Schmitt trigger circuit and a special feedback loop to a comparator to build a low overhead time redundancy scheme. The proposed structure masks internal node transient faults also improves the recovery of the output node by transferring the faulty output in two different paths to the comparison circuit’s inputs. Experimental results, simulated in 45 nm CMOS technology, show an acceptable increase in the critical charge compared with the previous hardened latches, with a fair increase in power, delay and area. Monte Carlo simulations have also confirmed the proposed latch resistance to the process, voltage and temperature variations.     

Transient processes in high-voltage silicon carbide bipolar-junction transistors

The specific features of transient processes in high-voltage silicon carbide bipolar-junction transistors are studied theoretically and experimentally. It is shown that, in good agreement with the experimental results, the switch-off from the active mode can be described in a wide temperature range by the simple analytical expression derived in the study. The process in which a transistor is switched on to pass into the active mode is well described by a simple exponential dependence. The time constant of the switch-on process is determined by the average value of the collector capacitance before and after switch-on. A numerical model is suggested, based on a simple and physically transparent equivalent circuit describing, in good agreement with the experiment, both the transient processes of switch-on and switch-off in a SiC bipolar junction transistor, in both the active and saturation modes.     

A study on cell association in heterogeneous networks with joint load balancing and interference management

This paper presents the characteristic analysis of channel gain for two conductor type power line communication (PLC) system using analytical transient model. The analysis of frequency responses is presented by incorporating various lengths of transmission lines and loads at terminal side. It is suggested that variations in the frequency responses of PLC channel, especially under transient condition within the transmission line (TL) can be investigated more effectively by using the transient model. Performance of transient model is found to be significantly better than the previously available work in the literature. More accurate results are achieved in simulation as compared to results obtained from typical \(\pi \) model of lumped circuit.     

用于GaN HEMT栅驱动芯片的快速响应LDO电路

设计了一种用于GaN高电子迁移率晶体管(High-Electron-Mobility Transistor,HEMT)器件栅驱动芯片的快速响应低压差线性稳压器(Low Dropout Regulator,LDO)电路,可为高速变化的数字电路提供快速响应的供电电压。该电路采用动态偏置结构,通过在大负载发生时给误差放大器增加一个额外的动态偏置结构,来加快输出端的瞬态响应速度。基于0.18μm BCD工艺,完成了电路设计验证。仿真结果显示LDO瞬态响应时间小于0.5μs,可满足频率达1 MHz的GaN HEMT器件栅驱动芯片应用要求。     

Generalized expressions for characterizing a linear multiportcircuit coupled with external fields

The outputs of a linear multiport circuit immersed in external fields are analyzed using the S-parameters in frequency and time domains. It is suggested that the matched output voltage is a proper and convenient parameter for characterizing the circuit coupled with external fields, since it can be measured easily in a higher frequency range than a few hundred megahertz. The output voltages of the circuit terminated with loads of arbitrary impedance are calculated from measured values of the matched output voltages, the S-parameters of the circuit, and the reflection coefficients of the loads. Related formulas are derived for the characterization     

一种高精度正弦波扫频信号发生器的设计与实现

作为一种新型外科手术器械，超声刀正在多个外科领域得到越来越多的应用。超声刀是一种功率超声波发生器，不同用途的超声刀工作于不同的频段，早期的超声刀都是针对某种人体组织设计的单频专用手术装置。提出了一种适用于多功能超声手术装置的正弦波扫频信号发生器。该信号发生器以单片机为控制核心，采用数字混频和自适应滤波技术，用高、低两个频率分别控制扫频信号的频带和分辨率的方案，解决了实现扫频电路中高频、窄带、高分辨率等指标的难题，为类似问题的解决提供了一种可选方案。该方案已成功用于“NTY300型多功能超声手术装置”项目，该项目获得国家科技进步三等奖。