The adaptive front - end has the adaptive ability for the magnitude and frequency of input signals . it can prefilter for the input signals , eliminate the useless signals , and improve the dynamic range of receiver system . it can lessen the burden of digital signal processing in the back - end of receiver , and improve the performance of receiver system 自适应接收机前端对输入信号有自适应能力? ?频率自适应和幅度自适应,这样的前端就可将系统的接收中心频率和带宽自适应到输入信号的频率和带宽,其实就是对输入信号进行一次预分选、预滤波,剔除对接收系统毫无作用的信号;同时对大信号自动减小增益,对小信号增加增益,提高系统的动态范围;而且可以对干扰信号进行压制。
In the section 1 , we have introduced the background and the recent advance of the flattened gaussian beam ; in the section 2 , for the first time , we have calculated the type - i and type - ii shg conversion efficiency and simulated curves versus the crystal length , the pumping light polarization rate , the order of the flattened gaussian beam and the pumped power intensity , we obtain ed that the highest efficiency was influenced by the order and the polarization rate of the pumped flattened gaussian beam 从三波耦合方程及clbo晶体的光学特性出发，讨论了以平顶高斯光束入射时稳态的三波耦合方程的大信号倍频解(包括类及类相位匹配的倍频解) 。计算了其在clbo晶体上的倍频转换效率与晶体长度，基波偏振分量比，基波阶数及泵浦波强度之间的相互影响关系曲线。得出影响平顶高斯光束的最高转换效率的因素是基波的阶数n和泵浦波的偏振分量比d 。
The principle of power amplifier is introduced at first in this paper , especially its nonlinearity characteristic under the condition of large signal . subsequently linearization technology such as power - retreat , negative feedback , pre - distortion and feed - forward are discussed . and then broadband matching technology is introduced . at last , the scheme of subject , the functional realization of each module , some questions which must be pay much attention in the system design , and the ultimate testing result of this subject is represented and analyzed in detail 本文首先介绍了线性功率放大器工作原理，尤其是在大信号条件下，它的非线性特征，这是设计线性功放必备的基础；接着介绍了当今一些前沿的功放线性化方法，例如预失真和前馈技术；然后详细讨论了宽带匹配技术，特别是传输线变压器的原理和应用，这是因为传输线变压器在本课题中扮演了重要的角色；最后具体叙述了本课题采用的方案、各个模块的功能的实现、实际设计应注意的问题。
The switch power possesses the advantages of compact size and high efficiency compared with conventional linear power which makes its wide application in the field of communication , computer , etc . in recently year , there is a rapid increasing market demanding for battery - powered portable equipments ( such as pdas , mobiles , etc ) , which requires the dc - dc converter with high efficiency to boost the battery supply capability and good large signal property to satisfy the special demand of the cpu , dsp and flash memory 相对于线性电源,开关电源具有体积小、效率高等优点,使其在通讯、计算机等领域得到广泛应用。近年来,电池供电便携式设备(如pda 、手机、 mp3播放器等)的需求越来越大,对dc - dc开关电源ic的需求也日益增大,同时对其性能要求是越来越高。要求dc - dc转换器具有高转换效率,以延长电池供电时间;并具有良好大信号特性,以满足cpu 、 dsp和闪存等模块要求。
Secondly , a network based on multi - terminal components modeling methodology was applied to model mems at system - level by the analogy and mixed - signal modeling tool of vhdl - ams , for the system - level model of mems is a mixed signal model , which has attributes of multi - energy domains coupling , multi - signals mixed and interacting between discrete - event subsystems and continuous - time subsystems . with this method , the whole system can be divided into some subsystems defined as multi - terminal components ; the behavior of the subsystems depends only on their terminal signals ; the information exchange between subsystems was done by the signals at their terminals . the continuous - time systems or discrete - event systems can be modeled and simulated with this method , which satisfied the requirements of nonlinear systems and large signals analysis 同时，针对mems的系统级模型是一个混合信号模型，具有多能量域耦合、多信号混合、离散事件子系统与连续时间子系统交互的特点，使用vhdl - ams作为混合信号模型建模的工具，采用多端口组件网络建模方法建立了mems系统级模型，把微型机电系统分解为多个子系统或组件，各子系统被定义为多端口组件，子系统的内部行为通过其端口行为来描述，子系统间的能量与信号的交换通过组件的端口映射来实现，从而实现了对连续时间系统和离散事件系统的建模与仿真，满足了非线性系统以及大信号分析要求。
At present , most majority of control projects are still based on state - space averaging model or linear small signal model , as a result , it solved the analytical problem of steady state and dynamic state low frequency signals . because of the strong non - linear of the system , the application scope of this simple model is limited greatly . to gain new breakthrough on the control of the dc - dc converter , we must establish a new , more precise and applied large signal discrete model , and we must develop unconventional sampling control theories 目前绝大多数控制方案仍然基于状态空间平均模型或线性化小信号模型，这较好地解决了pwm型dc - dc变换器的稳态和动态低频小信号的分析问题，但是又由于系统的强非线性，这种简单模型的适用范围受到了很大的限制， dc - dc变换器控制上要获得新的突破，必须建立一个新的、更精确和实用的大信号离散模型，还需要发展非传统的采样控制理论。
( 2 ) a new method of parameter setting for excitation systems is proposed . firstly , the large signal performance simulation test of the excitation system is conducted and the objective response of the excitation system is described with its large signal performance indexes , and then the parameters of the excitation system are identified . secondly , the small signal performance simulation test of the excitation system is done a nd the parameters of the excitation system are optimized by the 1tae rule in order to enhance the small signal regulation performance 提出了一种励磁系统参数整定方法：首先以大信号特性技术指标为目标，用gause - newton法对励磁系统参数进行辨识，确定符合标准的励磁系统参数；接着按照时间乘绝对误差的积分( itae )准则，用gause - newton法对励磁系统参数进行优化，以提高励磁系统的小信号调节性能。
Large signal model of gaas mesfet is built and , in the light of advanced pspice circuit simulation programme , the circuit transient and dc operation analyse and speed performances are calculated . and also , the inserted loss and isolation are optimized by microwave circuit software touchstn of eesof company 同时，建立了gaasmesfet器件大信号模型，用先进的pspice电路模拟程序对所设计的电路进行瞬态分析和直流工作点分析，计算电路的速度性能；用eesof公司的touchstn微波电路设计软件，进行开关的插入损耗和隔离度的优化设计。
The apfs using according detection method are investigated and developed by simulating and experimenting to demonstrate the performance of the proposed detection method and apf . secondly , a nonlinear , large signal control theory - one cycle control , which was presented in the 90 ' s and suitable especially for switch power converter ， was investigated . the integration reset control and extension applications ， which was < wp = 7 > developed based on one cycle control theory , was emphatically studied 本文深入分析了90年代初发展起来的一种适合开关变换器的大信号非线性控制理论? ?单周控制（ onecyclecontrol ）理论，以及在此理论基础上发展起来的常频积分复位控制技术和它的最新应用，首次成功地将单周控制理论应用于apf的检测和控制中，提出并实现了一种通用常频积分复位控制有源电力滤波器，从而简化了apf的工作原理和结构。
The synchronous rectifying and low power sampling technology is used to reduce the power consumption , flexible external loop compensation , error amplifier output clamp are adopted for better system large signal response . the piecewise slope compensation technology is employed to minimize the consequence of over compensation . the sensor resistor is externally connected , which realize output voltage programmable . the overheat protection and under voltage protection modules are integrated in the die to allow the reliable operation of the system 同时,电路设计采用同步整流技术、低功耗电流采样技术降低功耗,提高转换效率;采用灵活的外部环路补偿技术、误差放大器输出嵌位技术以实现良好大信号特性;采用分段斜坡补偿技术,消除不稳定因素,并最大程度地减小过补偿带来的问题;采用外接输出采样电阻的方式,实现输出电压的可编程。
