开关电源管耗计算及DC—DC电路分析

本文介绍了电源技术领域中的后起之秀──开关电源的特点，基本工作原理及电路中功率晶体管，二极管损耗的计算方法并将开关电源与传统电源进行了比较。文章还介绍了开关电源中常见的四种类型的ＤＣ—ＤＣ变换器并对其中两种进行详细分析，得出电路中各点电流电压波形，计算出电压变换比。

线性放大变频电源的散热设计

鉴于线性放大变频电源易受温度影响的特性,设计了一套相应的散热系统。通过详细的推导计算,建立了变频电源主放大电路的三极管总管耗的准确计算和估算方法。并利用热阻等效电路表示系统散热路径,且给出了关于热阻的三极管结温表达式。在此基础上,由对散热器、散热风道和通风机的优化设计,研制出一套应用于线性放大变频电源的强迫风冷散热系统。通过Icepak进行热场仿真并与实际试验的结果相对比,验证了设计方案的可行性。

GaAs PIN Diodes for X-Band Low Loss and High Isolation Switches

GaAs PIN diodes optimized for X-band low loss and high isolation switch application are presented. The impact of diode physical characteristics and electrical parameters on switch performance is discussed. A new structure for GaAs PIN diodes is proposed and the fabrication process is described. GaAs PIN diodes with an on-state resistance of 〈2. 2Ω and off-state capacitance -〈20fF in the range of 100MHz to 12.1GHz are obtained.

提高声频功率放大器输出功率和可靠性的方法

总结了设计大功率声频功率放大器会出现的某些问题,探讨问题的解决方案,并对大功率声频功率放大器的可靠性设计进行了讨论。

SOICMOS Integrated Circuit of Laser Range Finding Working at High Temperatures

Modeling analysis of thin fully depleted SOICMOS technology has been done. Using ISETCAD software,the high temperature characteristics of an SOICMOS transistor were simulated in the temperature range of from 300 to 600K, and the whole circuit of a laser range finder was simulated with Verilog software. By wafer pro- cessing,a circuit of a laser range finder with complete function and parameters working at high temperatures has been developed. The simulated results agree with the test results. The test of the circuit function and parameters at normal and high temperature shows the realization of an SOICMOS integrated circuit with low power dissipation and high speed, which can be applied in laser range finding. By manufacturing this device, further study on high temperature characteristics of shorter channel SOICMOS integrated circuits can be conducted.

OCL电路性能分析探讨

OCL电路的性能分析是模拟电子技术基础中的一个重要的技术点。本文对OCL电路相关内容表述存在的问题做了简要分析,并指出其中应该注意的问题,就性能分析过程做了详细的描述,以期更好地把握OCL电路的性能分析方法。

Simulation and Experimental Research on a Schottky Gate Resonant Tunneling Transistor

A Schottky gate resonant tunneling transistor （SGRTT） is fabricated. Relying on simulation by ATLAS software,we find that the gate voltages can be used to control the current of SGRTT when the emitter terminal is grounded and a positive bias voltage is applied to the collector terminal. When the collector terminal is grounded, the gate voltages can control the peak voltage. As revealed by measurement results, the reason is that the gate voltages and the electric field distribution on emitter and collector terminal change the distribution of the depletion region.

防止OTL与OCL功放电路的失真和烧管

在电子电路中,功放级所接的负载一般都是低阻抗的,使用OTL或OCL互补对称推挽功放电路以取代变压器耦合推挽功放电路,克服了变压器因铜损和铁损造成的功率损耗以及其漏感和分布电容在频率的高端和低端产生附加相移引起寄生振荡;克服了变压器体积大而且重、频带窄、不便于集成等缺点而迅速发展起来。但是,这种电路工作在甲乙类。

Complementary Pass-Transistor Adiabatic Logic Circuit Using Three-Phase Power Supply

A new low power quasi adiabatic logic,complementary pass transistor adiabatic logic (CPAL),is presented.The CPAL circuit is driven by a new three phase power clock,and its non adiabatic loss on output loads can be effectively reduced by using complementary pass transistor logic and transmission gates.Furthermore,the minimization of the energy consumption can be obtained by choosing the optimal size of bootstrapped nMOS transistors,thus it has more efficient energy transfer and recovery.A three phase power supply generator with a small control logic circuit and a single inductor is proposed.An 8 bit adder based on CPAL is designed and verified.With MOSIS 0 25μm CMOS technology,the CPAL adder consumes only 35% of the dissipated energy of a 2N 2N2P adder and is about 50% of the dissipated energy of a PFAL adder for clock rates ranging from 50 to 200MHz.

Application study of dynamic voltage scaling policies

Based on the fundamental relationship among the circuit power, the circuit delay and the supply voltage, four theorems associated with the application of dynamic voltage scaling （DVS） policies are proposed and proved. First, the existence characteristics of the optimal supply voltage for a single task are proved, which suggests that the optimal supply voltage for the single task should be selected only within a one-dimensional term, and the corresponding task end time by the optimal supply voltage should be identical with its deadline. Then, it is pointed out that the minimum energy consumption that the DVS policy can obtain when completing a single task is certainly lower than that of the dynamic power management （DPM） policy or the combined DVS＋DPM policy under the same conditions. Finally, the theorem of energy consumption minimization for a multi-task group is proposed, which declares that it is necessary to keep the processor in the execution state during the whole task period to obtain the minimum energy consumption, while satisfying the deadline constraints of any task.

Monolithic Integration of InGaP/AlGaAs/InGaAs Enhancement/Depletion-Mode PHEMTs

The monolithic integration of enhancement- and depletion-mode （E/D-mode） InGaP/AIGaAs/InGaAs pseudomorphic high electron mobility transistors （PHEMTs） with a 1.0μm gate length is presented. Epilayers are grown on SI GaAs substrates using MBE. For this structure, a mobility of 5410cm^2/（V · s） and a sheet density of 1.34 × 10^12 cm^-2 are achieved at room temperature. During the gate fabrication of E/D-mode PHEMTs,a novel twostep technology is applied. The devices with a gate dimension of 1μm × 100μm exhibit good DC and RF performances. Threshold voltages of 0. 2 and -0. 4V,maximum drain current densities of 300 and 340mA/mm,and extrinsic transconductances of 350 and 300mS/mm for E- and D-mode PHEMTs are obtained, respectively. The reverse gatedrain breakdown voltage is -14V for both E- and D-mode. Current-gain cutoff frequencies of 10. 3 and 12.4GHz and power-gain cutoff frequencies of 12.8 and 14.7GHz for E- and D-mode are reported, respectively.

Analysis and simulation of lateral PIN photodiode gated by transparent electrode fabricated on fully-depleted SOI film

A novel device, lateral PIN photodiode gated by transparent electrode （LPIN PD-GTE） fabricated on fully-depleted SOI film was proposed. ITO film was adopted in the device as gate electrode to reduce the light absorption. Thin Si film was fully depleted under gate voltage to achieve low dark current and high photo4o-dark current ratio. The model of gate voltage was obtained and the numerical simulations were presented by ATLAS. Current-voltage characteristics of LPIN PD-GTE obtained in dark （dark current） and under 570 nm illumination （photo current） were studied to achieve the greatest photo-to-dark current ratio for active channel length from 2 to 12 /am. The results show that the photo-to-dark current ratio is 2.0×10^7, with dark current of around 5×10^-4 pA under VGK=0.6 V, PrN=5 mW/cm2, for a total area of 10μm×10μm in fully depleted SOI technology. Thus, the LPIN PD-GTE can be suitable for high-grade photoelectric systems such as blue DVD.

Decomposition Analysis of Sectoral Energy Use in Beijing (1981-2005) Using the LMDI Method

This paper aims to identify the main driving force for changes of total primary energy consumption in Beijing during the period of 1981-2005.Sectoral energy use was investigated when regional economic structure changed significantly.The changes of total primary energy consumption in Beijing are decomposed into production effects,structural effects and intensity effects using the additive version of the logarithmic mean Divisia index (LMDI) method.Aggregate decomposition analysis showed that the major contributor of total effect was made by the production effect fol- lowed by the intensity effect,and the structural effect was rela- tively insignificant.The total and production effects were all posi- tive.In contrast,the structural effect and intensity effect were all negative.Sectoral decomposition investigation indicated that the most effective way to slow down the growth rate of total primary energy consumption (TPEC) was to reduce the production of the energy-intensive industrial sectors and improving industrial en- ergy intensity.The results show that in this period,Beijing's economy has undergone a transformation from an industrial to a service economy.However,the structures of sectoral energy use have not been changed yet,and energy demand should be in- creasing until the energy-intensive industrial production to be reduced and energy intensity of the region reaches a peak.As sequence energy consumption data of sub-sectors are not available, only the fundamental three sectors are considered:agriculture, industry and service.However,further decomposition into secon- dary and tertiary sectors is definitely needed for detailed investi- gations.

Nosing process of empty and foam-filled circular metal tubes on semispherical die by theoretical and experimental investigations

Nosing process of circular metal tubes in empty and polyurethane foam-filled conditions on a semispherical rigid die was analyzed by theoretical and experimental methods.A new theoretical model of plastic deformation of circular metal tubes was demonstrated during the nosing process on a rigid semispherical die.Based on the analytical model,some theoretical relations were calculated to estimate instantaneous forming load and dissipated energy of empty and foam-filled circular metal tubes versus axial displacement.Some circular brazen and aluminum tubes were prepared and shaped into semispherical nosed nozzles to verify the present theory.Comparison of theoretical predictions and the corresponding experimental measurements reveals that predicted load?displacement and dissipated energy?displacement diagrams by theoretical formulas have a good correlation with the corresponding experimental curves and it proves verity of the theory.Also,the present theory shows that dissipated energy and axial load of empty tubes depend on material type,wall thickness and diameter of the tubes and they are independent of tube initial length.Furthermore,the experimental results show that the presence of polyethylene Teflon-constraints increases ultimate axial displacement of the forming process.

Behavioral and physiological flexibility are used by birds to manage energy and support investment in the early stages of reproduction

Interest in phenotypic flexibility has increased dramatically over the last decade, but flexibility during reproduction has received relatively little attention from avian scientists, despite its possible impact on fitness. Because most avian species maintain atrophied reproductive organs when not active, reproduction in birds requires major tissue remodeling in preparation for breeding. Females undergo rapid （days） recrudescence and regression of their reproductive organs at each breeding attempt, while males grow their organs ahead of time at a much slower rate （weeks） and may maintain them at maximal size throughout the breeding season. Reproduction is associated with significant metabolic costs. Egg production leads to a 22%-27% increase in resting metabolic rate （RMR） over non-reproductive values. This is partly due to the activity of the oviduct, an organ that may allow females to adjust reproductive investment by modulating egg size and quality. In males, gonadal recrudescence may lead to a 30% increase in RMR, but the data are inconsistent and general conclusions regarding energetic costs of reproduction in males will require more research. Recent studies on captive female zebra finches describe the impacts of these costs on daily energy budgets and highlight the strategies used by birds to maintain their investment in reproduction when energy is limited. Whenever possible, birds use behavioral flexibility as a first means of saving energy. Decreasing locomotor activity saves energy during challenges such as egg production or exposure to cold temperatures and is an efficient way to buffer variation in individual daily energy budgets. However, when behavioral flexibility is not possible, birds must rely on flexibility at the physiological level to meet energy demands. In zebra finches breeding in the cold, this results in a reduced pace of laying, likely due to down-regulation of both reproductive and non-reproductive function, allowing females to defend minimal egg size and maintain reproductive success. More research involving a range of species in captive and flee-living conditions is needed to determine how phenotypic flexibility during tissue remodeling and early reproductive investment translates to natural conditions and affects fitness [Current Zoology 56 （6）： 767-792, 2010].

Facilities Management Carbon Footprints： An Audit of Critical Elements of Management and Reporting

Concern for the environmental impact of organizations＇ activities has led to the recognition and demand for organizations to manage and report on their carbon footprint. However, there is no limit as to the areas of carbon footprints required in such annual environmental reports. To deliver improvements in the quality of carbon footprint management and reporting, there is a need to identify the main elements of carbon footprint strategy that can be endorsed, supported and encouraged by facility managers. The study investigates carbon footprint elements managed and reported upon by facility manager in the UK. Drawing on a questionnaire survey of 256 facility managers in the UK, the key elements of carbon footprints identified in carbon footprint reports are examined. The findings indicate that the main elements are building energy consumption, waste disposal and water consumption. Business travel in terms of using public transport, air travel and company cars are also recognized as important targets and objectives for the carbon footprint strategy of several FM （facilities management） organizations.

Natural Resources Depletion in Hill Areas of Bangladesh:A Review

Hilly or mountainous terrain occupies around 12% of the area of Bangladesh.Natural resources associated with Bangladesh's hill are forest resources,biodiversity,minerals,and agricultural crops.Natural resources have been exploited in the recent four decades due to excessive clearing of hill forest cover,resulting in loss of species richness, impacts related to increased water flow variability, increased hill slope erosion and flooding intensity, and a gradual decrease in the extent of hill area in Bangladesh.This review explores the major causes and effects of depletion of natural resources by linking drivers,pressures and the related impacts.A review has been conducted to structure the effects on the hilly areas and describe the responses to minimize them in the associated DPSIR framework.Population growth has been identified as a major driver contributing to high deforestation rates.This may negatively effect agricultural productivity and increase the frequency of serious flooding.Slash and burn cultivation also impacts the regeneration of evergreen forests,which may accelerate soil erosion. Due to this and other factors,local people are facing a deficits of natural resources(food,fodder,fuel wood and water),which exacerbates the effects of poverty. Future research should try to facilitate decision making for sustainable utilization of natural resources management in the hilly areas of Bangladesh. Additional conservation measures should be developed to increase the resilience of ecosystems at national and regional levels.

Dissipation-Managed Bright Soliton in a 1D Bose-Einstein Condensate in an Optical-Lattice Potential

We study the formation of a dynamically-stabilized dissipation-managed bright soliton in a quasi-onedimensional Bose-Einstein condensate by including an imaginary three-body recombination loss term and an imaginary linear feeding one in the Gross Pitaevskii equation, trapped in a shallow optical-lattice potential. Based on the direct approach of perturbation theory for the nonlinear Schroedinger equation, we demonstrate that the height （as well as width） of bright soliton may have little change through selecting experimental parameters.

Theory and practice of value management and its innovation for natural resources from the perspective of sustainable development

The supreme obstacle for sustainable development of natural resources is the scarecity, bottleneck. So how to promote the sustainable utilizing and increase the using efficiency of natural resources is worth studying. This paper suggests that we should improve the model and means of evaluating method and value management based on th~ theory of natural resource compensation. This paper discusses the User Cost Method based on the microeeonomicaspect which can change the evaluating method for natural resources. From the perspective of value managemen model, we should use the User Cost Method to realize the linkage and integration of micro and macro eompensation for natural resources. Based on the evaluating and aecounting idea User Cost Method, this paper presents a theo. retical framework to harmonize and link micro and macro compensation for natural resources. At present, we should seek the new approach and method to manage natural resources, so can we realize the capitalization managemen focusing on the vahte management for natural resources.