查询词典 power amplifier

Later, it makes some comparison with four kinds of modulation technique, and finally, it implements the three-level PWM switching power amplifier with the PWM technique. The power of the amplifier is 2kVA, and the frequency bandwidth is 10～3kHz. In the thesis, the author designs and makes the hardwares of the switching power amplifier. The hardwares contain power inverter rank circuit, control system circuit based on DSP, drive and isolation circuit, and protective circuit. The thesis also analyses the potential safety problems and put forward some solutions for the problems. Furthermore, the thesis accomplishes the software design of the control system, and successfully debugs it. The methods of designing higher power ampilfier are also discussed in the thesis. It analyses the feasibility of the methods, outlines the way of how to design higher power switching power amplifier, and does some experiments with the method of switches-parallelling.

根据电动振动试验系统对开关功放的要求，提出了以电感电流瞬时值控制技术为基础的三电平脉宽调制开关功放的设计方案，并通过系统仿真进行了原理性论证；然后设计并制作了开关功放的硬件，包括功率转换电路，基于DSP的控制电路，驱动、隔离电路以及保护电路；针对开关功放数学模型不易得出的特点，细致分析了模糊自适应PID控制方法，在此基础上编写了控制程序；研制出一台功率为2kVA，通频带为10～3kHz的三电平脉宽调制开关功放；论文中还探讨了实现大功率开关功放的方法，分析了各种方法的可行性，给出了实现大功率开关功放的思路，并进行了并联开关管实现大功率开关功放的实验。

In the electronic system, a power amplifier which provides magnetic coil with exciting current to produce electromagnetic force is one of the main components. General commercialization of power amplifiers can not meet the application requirements, but should be designed.Power amplifiers are divided into linear amplifier and switching amplifier.

磁悬浮轴承是典型的机电一体化系统，在其电控系统(传感器、控制器和功率放大器)中，功率放大器具有重要的作用，它向电磁铁线圈提供相应的控制电流以产生所需要的电磁力。

The ways of parallel resonant DC link and three-level control strategy were used in this power amplifier circuit. Output current ripple of power amplifier can be reduced as three-level power amplifier, all of power switches work on and off under the zero voltage switching or zero current switching, loss of switching and current ripple interference effectively reduced.

该电路在功率放大器三电平控制策略的基础上应用了并联谐振直流环节，保持了三电平功率放大器输出电流纹波小的优点，同时功率器件均工作在零电压或零电流条件下，开关损耗、电流纹波干扰有效地减小。

High-frequency continuous modulation on the high-power semiconductor laser is required in our ladar system. The theory and driving methods of the semiconductor laser is summarized in this article. Two kinds of driving circuit including linear power amplifier and resonance power amplifier are designed for continuous and quasi continuous modulated laser.

针对研制的无扫描激光雷达系统，需要对大功率半导体激光器进行高频连续调制，本文总结了半导体激光器的原理和驱动方法，并针对连续和准连续调制大功率激光器的特点分别设计了两套驱动电路，包括线性功率放大驱动电路和谐振功率放大驱动电路。

Power amplifier has high request for signal nondistortion, waveshape precision, output power, and function stability. Therefore, Power amplifier is a technical difficulty in the design of relay protection testing device.

功率放大器在信号不失真、波形精度、输出功率、运行稳定性等方面都有较高要求，因此是继电保护测试仪设计中的一个技术难点。

The switching power amplifier is optimized based on the achievement of electromagnetic force, and the circuit structure of tristate power amplifier with soft-switching is designed. This circuit owns the advantages of reducing the dissipationpower on the power component and improving the speed of system dynamic response, enhancing the stability of the electromagnetic force in the final state, and the nice result is presented by the simulation. The small-signal model of the power amplifier is also established.

在实现支撑所需的电磁力基础上，对开关功率放大器电路进行了优化设计，采用三电平软开关的电路结构，以降低主功率器件的功耗、提高系统的动态响应速度、提高稳态电磁力的平稳性；仿真分析表明可以达到预期的效果；最后还建立了功率放大器的小信号模型，为控制系统的调节器设计提供了依据。

Mobile phone RF system consists mainly of transceivers, power amplifier and antenna switch. PA might be set in the Front-End-Module or FEM. In 2G, the cost of RF system was only about US $1.5, while In 3G, the cost was increased to between US$6.0 and US$8.0, and the cost will further increased to about US$8.0 to US$10.0 in 4G, obviously, FR system had the highest cost growth during the upgrading of mobile phones.

手机射频系统有三个主要零组件，收发器、功率放大器（Power Amplifier，下简称PA）和天线开关，有时PA包含在前端模块（Front-End-Module，简称FEM）。2G时代的射频系统只占大约1.5美元的成本，3G时代则占大约6-8美元的成本，4G时代则占大约8-10美元的成本，也是手机升级换代成本增加最多的部分。

Those provide a practical and valid method for designing a feedforwardpower amplifier. Utilizing these and for TD-SCDMA we research and develop thedivider, coupler, bridge and power amplifier at 2.35GHz. Finally I accomplished asimple and minimal structured feedforward power amplifier. Its measured third-orderintermodulation distortion is -50dBc, which is 40dB greater than there is nolinearization technique.

根据分析结论，针对中国自主开发的TD-SCDMA 标准，设计实现了2.35GHz 的功分器、功率合成器、耦合器以及矢量调制器和功率放大器，最终实现了结构简单、体积小巧的前馈功放系统，完成了对放大器的线性化，三阶交调系数优于-50dBc 比线性化之前三阶交调系数改善了40dB。

GaAs RF switch MMICs for cellular phone; GaAs RF power amplifier MMICs for cellular phone; GaAs RF switch MMICs for base station; GaAs RF attenuator MMICs for base station; RF module for base station; GaAs power amplifier MMICs for CATV; MOSFET power devices;SAW resonators; SAW filters; SAW duplexers; N type and P type 4＂-6＂silicon epitaxial wafers.

这次参展的产品有：用于移动蜂窝电话的砷化镓射频单片集成电路；用于移动通信基站的射频IC及电路模块；用于CATV的砷化镓IC；MOSFET等功率器件；声表面波谐振器；声表面波滤波器；声表面波双工器；4＂-6＂N型和P型各类硅外延片。

The weight and volume of the power electronics equipment will be minished greatly by using switch-mode power amplifier instead of the traditional linear power amplifier.

采用电力电子开关功率放大器取代传统的线性功率放大器，极大地减小了装置的体积和重量。

The absorption and distribution of chromium were studied in ryeusing nutrient culture technique and pot experiment.

采用不同浓度K2CrO4(0，0.4，0.8和1.2 mmol/L)的Hoagland营养液处理黑麦幼苗，测定铬在黑麦体内的亚细胞分布、铬化学形态及不同部位的积累。

By analyzing theory foundation of mathematical morphology in the digital image processing, researching morphology arithmetic of the binary Image, discussing two basic forms for the least structure element: dilation and erosion.

通过分析数学形态学在图像中的理论基础，研究二值图像的形态分析算法，探讨最小结构元素的两种基本形态：膨胀和腐蚀；分析了数学形态学复杂算法的基本原理，把数学形态学的部分并行处理理念引入到家实际应用中。