功放的选配

通常音箱的推动功率都标注以较宽的范围。较大的功率值受限于音箱所能够承受的功率，而较小的功率值则为在一间小的听音室内能够获得适当的声压电平（SPL）的功率。 说起功率来，我们不主张使用所谓的音乐功率或是什么RMS（均方根值）的功率。原因是音乐功率有点名不正言不顺，且标注准值过于夸大或缺乏严格的科学定义。至于RMS功率实无其事，因为电压和电流倒是有RMS值，但RMS功率又从何而来？说实际一些，音箱的承受功率应指音箱在重放音乐或语声信号时所需的功率，而且还不是被限幅时的功率，即功率放大器恒定且连续输出的功率。 …     

双包层Er3 + /Yb3 + 共掺光纤放大器动态特性研究

基于速率方程的离散算法，实现了对双包层Er^3＋／Yb^3＋光纤放大器动态特性的分析。研究了不同信号和泵浦功率下单信道的瞬态功率、脉冲序列输出功率与增益随时间的变化以及多信道异步转移模式下输出功率和增益随时间的变化。结果表明：对于单个脉冲，在相同的泵浦功率下，输出脉冲的峰值功率取决于输入脉冲的峰值功率；在不同的泵浦功率下，输出脉冲的峰值功率取决于泵浦功率。对于脉冲序列，在达到稳定的输出前，将经历一个输出功率和增益由高到低的变化过程。对于异步转移模式的多信道脉冲，脉冲重叠时的功率和增益变化要快于非重叠时功率和增益的变化。     

横向高压功率器件的进展

由于横向高压功率器件在功率集成电路及智能功率电路中具有极其重要的用途，近年来，各种各样的横向功率器件层出不穷。文章讨论了近年来横向功率器件的发展及其主要特性，并对它们进行了详细的分类，以期对各种横向功率器件的特性及其优缺点有一个全面的了解。     

MPWC模块在微功率直放站的应用

本文分析了通信微功率直放站的技术及市场形势，微功率直放站工作原理及框图，微功率直放站的应用环境，广嘉MPWC芯片在微功率直放站的应用案例。     

问题：车载电台在车内用最高功率发射（25W）对人体的辐射很严重吗？

答：首先，还是驻波比的问题。驻波比可以直观地理解为正向功率和反射功率之比，SWR=1的时候车载电台发射的功率全部被天线系统发射出去，没有反射功率；如果天线开路，也就是所有的功率一点没出去，全部反射打回来施展在车载电台上，电台就危险了。     

CDMA移植通信中的功率控制

本文分析了ＣＤＭＡ移动通信系统中功率控制用的信号参数，介绍了功率测量，功率控制的基本方法和实现技术，以有功率控制下的系统性能。     

音频功率放大器功率传输及效率问题的探讨

讨论音频功率放大器功率传输及效率问题。通过分析和计算，得到传输功率、效率随负载变化的关系，认为在实际应用中，根据具体的功率要求，应兼顾传输功率和效率，合理地配接最佳负载。     

数字电视发射机功率分配器的设计

本文基于微带线理论，简要分析了功率分配器的设计原理，详细地介绍了功率分配器的设计步骤，并以等功率分配的二路功率分配器为例进行了实例分析。     

用于能量回收逻辑的正弦功率时钟电路

分析了功率时钟对电容负载充电与回收的物理过程，研完了正弦功率时钟产生电路的基本结构，考虑了功率时钟的频率与相位的稳定性。在此基础上，提出了稳定功率时钟频率与相位的功率时钟产生电路，即接入外部参考时钟，使振荡电路与参考时钟同步。用0．8μm DPDM CMOS工艺实现了一个简化的两相正弦功率时钟产生电路，通过物理测试，验证了电路的工作原理。     

无线自组网的功率控制与节能

随着无线通信的日益发展，无线自组织网络正逐渐从军用扩大到民用等诸多领域。但是无线自组织网络一般由电池供电，由于提高电池容量的技术进步缓慢，功率控制是一个重要的研究课题。无线自组织网络中的功率控制机制研究主要集中在3个方面，即网络层功率控制、链路层功率控制以及混合功率控制。重点是从分层的角度对功率控制进行阐述，主要介绍了网络层及链路层的功率控制，并介绍了一些节能协议。跨层设计综合考虑了各层性能能更好地为功率控制与节能服务。     

Millimeter-wave Gunn oscillator in series operation

The feasibility of series operation of a Gunn-diode oscillator in a millimeter-wave range is demonstrated. Oscillator output power and its dc-to-RF conversion efficiency can both be increased substantially by operating two Gunn diodes in series. Output power from two diodes in series operation is higher than twice the output power obtained from one individual diode. We report that the pulsed output power from two GaAs Gunn diodes in series operation reaches 4.4 W at a frequency of 33.2 GHz.     

Pulsed GaAs f.e.t. operation for high peak output powers

Significant increases in GaAs f.e.t. X-band power output are made possible by pulsed operation, using pulse durations sufficiently short that thermal limitations are alleviated. Significantly higher-voltage operation is also possible under these conditions, with further improvement in power output and gain. As much as 5.9 W of peak power output has been obtained at 8 GHz from a device capable of 2.5 W c.w. output at 6 GHz.     

低电压Charge-Recovery逻辑电路的设计

提出了一种新的适用于低电压工作的 sem i- adiabatic逻辑电路—— Dual- Swing Charge- Recovery L ogic(DSCRL) .该电路由 CMOS- latch- type电路及负载驱动电路构成 ,对负载的驱动为 full- adiabatic过程 .DSCRL 的电源为六相双峰值脉冲电源 ,低摆幅脉冲用于驱动负载 ,高摆幅脉冲用于驱动 CMOS- latch- type电路 .降低负载上摆幅时驱动负载的 NMOS管的栅压可以保持不变 ,有效地解决了传统的 adiabatic电路在低电压工作时 charge- re-covery效率降低的问题 .文中比较了 DSCRL 电路与部分文献中的 semi- adiabatic电路的功耗 ,DSCRL 在低电压工作方面     

The output power of a 6328-Å He-Ne gas laser

Expressions are derived for the output power of a gas laser in single-mode operation. This theory is then extended to multimode operation where the mode spacing is less than the pressure-broadened "natural" atomic linewidth. Using measured values for the linewidth and saturation parameters, these formulas are used to predict 6328-Å output power for a He-Ne laser as a function of laser gain, cavity loss, and output coupling. Experiments are reported which show good agreement with the theoretical predictions, and it is concluded that the theory presented here is adequate to describe the main features of the power output behavior of a 6328-Å He-Ne gas laser.     

Coherent lasers turn up the power

Three categories of multiwatt, coherent laser designs are discussed. The designs are single-mode waveguides suitable for output powers in the order of 200 mW, single-mode operation of multimode lasers, which are suitable for operation between 0.5 and 1.0 W, and the monolithically integrated master-oscillator power amplifier (M-MOPA) designs that have demonstrated 4.5 W of spectrally coherent output power and more than 0.8 W of single-lobe diffraction-limited output power in a technology that is scalable to even higher output powers. Laser-diode design architectures and the unique properties of semiconductor materials are reviewed     

一种提高垂直腔面发射激光器性能的新工艺

采用一种新的工艺方法提高了垂直腔面发射激光器的输出功率.采用开环分布孔代替环形沟槽,使器件的输出功率提高了0.34倍.14μm孔径的器件输出功率超过10mW,工作电流为29.6mA时,最大输出功率达到12.48mW.而且,这些开环分布孔为电注入提供了便捷的桥通道,很好地解决了电极易过沟断线问题.器件表现了良好的高温工作特性,当温度高达60℃时输出功率仍可达到8mW.     

218 W quasi-CW operation of 1.83 μm two-dimensional laser diodearray

218 W quasi-CW output power has been measured from a 1.83 μm InGaAsP/InP 90 element rack and stack configuration array. Despite strong dependence of the device efficiency on temperature, a CW output power of 54 W has been obtained. The maximum efficiency for CW operation was 18% for 30 W CW output power     

自调Q掺铒光纤激光器动态特性研究

为了研究自调Q掺铒光纤激光器输出动态特性,采用搭建全光纤结构的线形腔和环形腔自调Q掺铒光纤激光器进行了理论分析和实验验证。实验中,当抽运功率达到起振阈值后,随着抽运功率的增加,用示波器观察输出激光,线形腔输出激光依次经历了连续波、自调Q两种运行状态,由于抽运功率的限制,未能再次出现连续波运行状态,而环形腔输出激光则先经历了自调Q运行状态,然后是连续波运行状态;线形腔在抽运功率21mW~190mW的范围内,可获得脉冲宽度8s ~100s范围内可调、重复频率2.5kHz~54kHz范围内可调的自调Q脉冲;环形腔在抽运功率为16.2mW~110mW时,可获得的脉冲宽度在165s左右。结果表明,自调Q掺铒光纤激光器因腔结构的不同,输出激光动态特性也不同;线形腔和环形腔均有自调Q脉冲输出,但线形腔自调Q范围更大。     

Development of multimegawatt gyrotrons for fusion plasma heating and current drive

High-frequency gyrotrons with high output power are mainly used for microwave heating and current drive in plasmas for thermonuclear fusion. The development of high-power gyrotrons in continuous wave (CW) operation has been in progress for several years in a joint collaboration between different European research centers and an industrial partner. The status of the development of the 140-GHz continuously operating gyrotrons with an output power of 1 MW for the stellarator Wendelstein 7-X will be described. An output power of 890 kW has been achieved with a pulse length of 3 min. limited by the available high-voltage power supply at an electron beam current of 40 A. At a reduced beam current of 27 A , an output power of 540 kW was measured with a pulse length of 939 s. For the next fusion plasma device international thermonuclear experimental reactor, gyrotrons with a higher output power of about 2 MW are desirable. In short-pulse experiments, the feasibility of fabrication of coaxial cavity gyrotrons with an output power up to 2 MW, CW, has been demonstrated, and the information necessary for a technical design has been obtained. An output power of 2.2 MW has been reached in stable operation (without mode competition). At the nominal output power of 1.5 MW an efficiency of 48% could be obtained with single-stage depressed collector. The development of frequency tunable gyrotrons operating in the range from 105 to 140 GHz for stabilization of current driven plasma instabilities in fusion plasma devices (neoclassical tearing modes) is another task in the development of gyrotrons at the Forschungszentrum Karlsruhe.     

A new process to improve the performance of 850 nm wavelength GaAs VCSELs

In this article, we propose a new process method to improve the light output power of GaAs vertical-cavity surface-emitting lasers (VCSELs). The VCSELs with filling Al metal into the ring trench will exhibit a higher quantum efficiency and have a light output power of 1.45 times higher than those without filling Al. In addition, the trench filled with Al metal can benefit in the bonding process and behavior as a mirror to reduce the output power loss. These VCSELs show good output characteristics and high-temperature operation.