低功耗高增益宽带放大器外文翻译.doc

低功耗高增益宽带放大器 中文翻译增益放大器的增益是输出或输入功率之比，通常以分贝衡量。（当它是对数分贝测量相关的功率比：G(dB)=10 log(Pout /(Pin)）。射频放大器往往在最大功率增益所取，而音频放大器的电压增益和仪表放大器将更加经常指定（因为放大器的输入阻抗，往往会比源阻抗较高，负载阻抗高于放大器的输出阻抗）。例如：20分贝将有10倍的电压增益（100倍功率增益，只会发生在的输入和输出阻抗是一样的情况）带宽放大器的带宽是表示放大器提供了“良好”的频率范围，可为不同的应用。然而，共同的和普遍接受的衡量标准是半功率点（即在断电的频率降低一半的峰值）在输出与频率的曲线。因此，带宽可以被定义为下限和上限之间的半功率点的差异。因此，这是也是众所周知的-3 dB带宽。带宽（或称为“频率响应”公差为其他反应），有时引用（-1分贝，-6分贝等），或“加或减为1dB”（大致音量差异的人通常可以检测到）。 一个良好的质量赢得全音域音频放大器将基本持平，20赫兹至20千赫（正常人类的听觉范围）。超高保真放大器设计，放大器的频率响应应该大大超过这个扩展（一个或多个八度任何一方），并有可能-3 dB点 65千赫。专业旅游放大器往往输入和/或输出滤波大力限制频率超过20赫兹，20赫兹的反应;太多的放大器的潜在输出功率很大，否则是对声波和超声波频率浪费，以及调幅无线电干扰的危险会增加。现代开关放大器必须在陡峭的低通滤波的输出获得的高开关频率的噪声和谐波消除。效率 效率是如何的权力来源是非常有用的应用到放大器的输出措施。 A类放大器是非常低效的10-20之间，与25的输出直接耦合最大效率。电感耦合的输出可以提高效率50为上限。 B类放大器具有很高的效率，而且是因为高层次的失真（见：交叉失真音频工作不切实际）。在实际设计中，一个折衷的结果是AB类设计。 AB类放大器是现代之间通常35-55，其中78.5的理论最大效率。 市售D类开关放大器有报道高达90的效率。 CF卡类放大器通常被称为是非常高效率的放大器。 更高效的放大器运行冷却器，而且往往并不需要，即使在多千瓦的冷却风扇的设计。此是，由于生产效率损失按损失的能源产品的过程中能量转换热能的原因。在更有效的放大器有较少的能量损失，从而使更少的热量。 在射频功率放大器，如蜂窝基站和广播发射机，专门设计技术被用来提高效率。多尔蒂设计，其中使用第二个晶体管，可以摆脱典型的效率高达15，在一个狭窄的30-35的带宽。信封跟踪设计能够实现高达60的效率，通过调节与信号的包络的电源电压在线路放大器。 线性 一个理想的放大器将是一个完全线性器件，但真正的放大器只在一定限度内的线性关系。 当信号驱动放大器的增加，产量也增加，直到达到一个点，有部分放大器的部分变得饱和，不能产生任何更多的产出，这就是所谓的剪报，以及扭曲的结果。 在大多数放大器在增益减少发生之前，很难发生削波，结果是一个压缩效应，（如果放大器是音频放大器）听起来更刺耳的声音。对于这些放大器，1分贝压缩点的定义是：输入功率（或输出功率）当增益为1分贝的小信号增益比少。有时候这是故意设计的非线性减少超载下的硬剪辑发声不愉快。 对非线性问题是最经常与负反馈解决。 线性化是一个新兴的领域，有许多技术，如前馈，预失真，postdistortion，能效比，LINC技术，卡勒姆，笛卡尔反馈等，以避免非线形性的不良影响。 噪音 这是一个多大的噪音是在放大过程中引入的措施。噪声是一种电子装置和组件，同时从生产和设计时的噪音故意经济的必然产物，但结果不理想。对于噪声的电路的性能指标是噪声的数字或噪音的因素。噪声系数是一个与输出信噪比与输入信号的热噪声的比较。 输出动态范围 输出动态范围的范围，通常以dB给出了最小和最大之间的有用的输出水平。有用的最低水平是有限的输出噪声，而最大的是最经常受到扭曲。这两个比例是引述放大器的动态范围。更确切地说，如果S =最大允许信号功率和N =噪声功率，动态范围DR是何=（s的A + N）的/注1 在许多开关式放大器，动态范围是有限的最小输出的步长。 压摆率 压摆率是最高的输出变化率，通常在每秒（或微秒伏特引用）。许多放大器最终摆率限制（通常由一个驱动电流不得不克服一些电路中的电容效应点），有时远远低于限制放大器的小信号频率响应的全功率带宽频率阻抗。 上升时间 上升时间，章一个放大器，是为输出所需的时间从10调整到90级时的最后一个步骤输入驱动。对于高斯响应系统（或一个简单的RC滚关闭），上升时间是近似的： 章*体重= 0.35，其中TR是在几秒钟内上升时间和体重是赫兹的带宽。 建立时间和振铃 为输出解决在最终价值的一定百分比，例如0.1（所需的时间）被称为沉淀时间，通常是示波器垂直放大器和高精度测量系统中指定。振铃是指输出的变化，上述周期和低于1放大器的最终价值，导致在实现稳定的输出延迟。铃声响过冲的结果是由一个欠阻尼电路引起的。 过冲 在回答一个步骤的投入，超调量的输出量超过其最终的稳态值。 稳定性 稳定是符合所有反馈放大器的问题，无论是反馈结果无意或有意添加。尤其是当它是一个放大阶段在多个应用的问题。 稳定是在射频和微波放大器的主要问题。一个放大器的稳定程度，可量化的一个所谓的稳定因素。有几种不同的稳定因素，如斯特恩稳定的因素和Linvil稳定因素，其中一个必须指定为放大器的绝对稳定性会见了它的两个端口参数方面的条件。 电子放大器 主条目：电子放大器 常见的有广播和电视发射机和接收机使用的高逼真度（“高保真音响”）立体声设备，微型计算机及其他电子数码设备，吉他和其他乐器放大器电子放大器，许多类型。关键组件包括例如真空管或晶体管有源器件。简要介绍了电子放大器的多种类型如下。 功率放大器 术语“功率放大器”是一个关于交付给负载和发电量的相对长期/或由电源电路来源。一般来说功率放大器被指定为一个传播链（最后放大器的输出级），是放大器阶段，通常需要最关注的电源效率。效率的考虑导致各类功率放大器：见功率放大器类。 真空管（阀门）放大器 主条目：阀放大器 从四个“Harmonix的KT88电”的品牌力量管亮起了一特雷诺为YBa - 200吉他放大器内发光 据西蒙斯，而半导体放大器已在很大程度上取代了低功耗应用阀放大器，阀放大器得多的成本，如“雷达对抗装备，通信设备”（第56页）高功率应用有效。许多微波放大器是专门设计的阀门，如速调管，回旋管，行波管，交叉场放大器，这些微波阀门提供更大的单器件在比固态装置（第59页的输出功率微波频率） 2。 阀门/管放大器也有其他方面利基用途，例如 俄罗斯军用飞机，为他们的电磁脉冲容忍 利基音频他们的声音质量 晶体管放大器 主条目：晶体管，双极型晶体管，音频放大器和MOSFET 这一积极因素的基本作用是放大输入信号，以产生输出信号大得多。量的放大（以下简称“远期收益”）是由外部电路设计以及有源器件。 许多常见的晶体管放大器有源器件的双极结晶体管（BJT）和金属氧化物半导体场效应晶体管（MOSFET）。 应用多不胜数，一些常见的例子是音频放大器在家庭立体声或扩音系统，射频半导体设备的高发电，射频和微波无线电发射器等应用程序。 晶体管的放大器可以实现使用不同的配置：例如一个双极结晶体管可以实现我们共同的基础，共集电极或共发射极放大器，我们可以使用一个MOSFET实现共同的门，常见的来源或共同漏放大器。每个配置有不同的特性（增益，阻抗.)（运算放大器运算放大器） 主要文章：运算放大器和仪表放大器 运算放大器是一种具有很高的开环增益和差分输入的员工为它的传递函数或外部反馈放大器增益控制电路。虽然长期是今天普遍应用到集成电路，原来的运算放大器设计与阀门执行。 全差分放大器（FDA）的 主要文章：全差分放大器 全差分放大器是一种固态集成电路放大器，采用了与它的传递函数或增益控制的外部反馈。它类似于运算放大器，但它也有差分输出引脚。 视频放大器 这些处理视频信号，并根据不同的带宽是否为标清视频信号，EDTV，HDTV的720p或1080i / p等的。该规范本身的带宽取决于什么样的过滤器使用，哪些点（-1分贝或-3分贝例如）的带宽是衡量。步反应和过冲的某些要求是必要的，以便接受电视图像显示方式。 示波器垂直放大器 这些是用来处理视频信号驱动一个示波器显示管，可以有大约500兆赫带宽。对阶跃响应，上升时间，过冲和畸变的规格可以使这些放大器的设计非常困难。在高带宽的垂直放大器的先驱之一，是泰克公司。 分布式放大器 主要文章：分布式放大器 这些使用的传输线路，暂时分裂的信号和健全各部分分离出来，以实现更高的带宽比可以从一个单一的扩音设备获得的。每个阶段的输出在输出相结合，传输线。这种类型的放大器是常用的，因为最后的垂直放大器示波器。该输电线路常常住显示管玻璃内的信封。 开关模式放大器 这些非线性放大器比线性放大器的效率要高得多，其中，用于节能证明额外的复杂性。 负阻器件 负电阻可用于放大器，如隧道二极管放大器。 微波放大器 行波管（TWT）放大器 主条目：行波管 用于低频率高功率微波放大。它们通常可以放大跨越广泛的频率，但他们通常并不如速调管可调。 速调管 主条目：速调管 行波管放大器很相似，但功能更强大，用特定频率的“甜蜜点”。他们一般也比行波管放大器较重，因此轻质不适合移动应用。速调管是可调的，提供其指定的频率范围内选择输出。 乐器（音响）放大器 主条目：仪器放大器和音频放大器 音频放大器通常用于放大，如音乐或语音信号背景：没有一个分布式放大器，宽带放大器带宽最可达到约1 / 10到其fT的1 / 3只。因此，一个高带宽放大器需要高英尺（至少3-10倍的放大器带宽）晶体管，以实现高带宽。不幸的是，当前的设备技术是有限的，在非常高的fT晶体管，产量仍然较低。这导致高成本，低产量的影响。 即使高增益带宽产品可以通过一个分布式放大器实现了分布式放大器的主要缺点是大面积，高直流功率消耗。 晶体管的操作，高电流密度高的fT为了实现高带宽的扩增。但是，晶体管会变得高度的可靠性问题，并强调在短寿命造成的。 50欧姆终端目前雇用的输入和输出的宽带放大器，以获得理想的输入和输出宽带匹配阻抗（低的S11和S22）。但是，缺点是在他们的投入和产出的3分贝损失。技术：大学的研究人员已经开发相结合三个阶段的放大器的设计与实现理想的增益，大带宽，低功耗，低输入/输出反射系数，低损耗宽带放大器的设计方法，可靠性好。如果没有一个分布式放大器，宽带放大器所发明的1 / 2尺，带宽/或临近ft可以实现。因此，放大器只需要1-3倍的fT放大器的带宽，以实现高带宽。该地区的宽带放大器和直流功率消耗将是小型，低分别。 随着宽带放大器的发明，晶体管的典型操作电流密度，但高放大器的带宽仍然可以实现。因此，晶体管是没有强调在高电流密度，从而导致更好的可靠性和长生命周期。此外，50终止不需要在输入和输出宽带匹配网络，因此，一个3 - dB的损失是可以避免的。 S11为低，可以保持甚至超过了直流工作带宽从0到3.3V电源，和S22是在工作带宽低。这种优势是非常有用的宽带放大器，它们可以很容易地级联以及。 宽带放大器可用于调制器驱动程序光纤通信，自动增益控制和阻放大器。也可以作为受聘于在无线通信系统的通用放大器频率不同的条带，测试设备，军事电子战系统。 A Broadband Amplifier with Huge Gain-bandwidth Product and Low Power Consumption GainThe gain of an amplifier is the ratio of output to input power or amplitude, and is usually measured in decibels. (When measured in decibels it is logarithmically related to the power ratio: G(dB)=10 log(Pout /(Pin). RF amplifiers are often specified in terms of the maximum power gain obtainable, while the voltage gain of audio amplifiers and instrumentation amplifiers will be more often specified (since the amplifiers input impedance will often be much higher than the source impedance, and the load impedance higher than the amplifiers output impedance).Example: an audio amplifier with a gain given as 20dB will have a voltage gain of ten (but a power gain of 100 would only occur in the unlikely event the input and output impedances were identical). BandwidthThe bandwidth of an amplifier is the range of frequencies for which the amplifier gives satisfactory performance. The definition of satisfactory performance may be different for different applications. However, a common and well-accepted metric is the half power points (i.e. frequency where the power goes down by half its peak value) on the output vs. frequency curve. Therefore bandwidth can be defined as the difference between the lower and upper half power points. This is therefore also known as the 3 dB bandwidth. Bandwidths (otherwise called frequency responses) for other response tolerances are sometimes quoted (1 dB, 6 dB etc.) or plus or minus 1dB (roughly the sound level difference people usually can detect).The gain of a good quality full-range audio amplifier will be essentially flat between 20Hz to about 20kHz (the range of normal human hearing). In ultra high fidelity amplifier design, the amps frequency response should extend considerably beyond this (one or more octaves either side) and might have 3 dB points 65kHz. Professional touring amplifiers often have input and/or output filtering to sharply limit frequency response beyond 20Hz-20kHz; too much of the amplifiers potential output power would otherwise be wasted on infrasonic and ultrasonic frequencies, and the danger of AM radio interference would increase. Modern switching amplifiers need steep low pass filtering at the output to get rid of high frequency switching noise and harmonics.EfficiencyEfficiency is a measure of how much of the power source is usefully applied to the amplifiers output. Class A amplifiers are very inefficient, in the range of 1020% with a max efficiency of 25% for direct coupling of the output. Inductive coupling of the output can raise their efficiency to a maximum of 50%.Class B amplifiers have a very high efficiency but are impractical for audio work because of high levels of distortion (See: Crossover distortion). In practical design, the result of a tradeoff is the class AB design. Modern Class AB amplifiers are commonly between 3555% efficient with a theoretical maximum of 78.5%.Commercially available Class D switching amplifiers have reported efficiencies as high as 90%. Amplifiers of Class C-F are usually known to be very high efficiency amplifiers.More efficient amplifiers run cooler, and often do not need any cooling fans even in multi-kilowatt designs. The reason for this is that the loss of efficiency produces heat as a by-product of the energy lost during the conversion of power. In more efficient amplifiers there is less loss of energy so in turn less heat.In RF Power Amplifiers, such as cellular base stations and broadcast transmitters, specialist design techniques are used to improve efficiency. Doherty designs, which use a second transistor, can lift efficiency from the typical 15% up to 30-35% in a narrow bandwidth. Envelope Tracking designs are able to achieve efficiencies of up to 60%, by modulating the supply voltage to the amplifier in line with the envelope of the signal.LinearityAn ideal amplifier would be a totally linear device, but real amplifiers are only linear within limits.When the signal drive to the amplifier is increased, the output also increases until a point is reached where some part of the amplifier becomes saturated and cannot produce any more output; this is called clipping, and results in distortion.In most amplifiers a reduction in gain takes place before hard clipping occurs; the result is a compression effect, which (if the amplifier is an audio amplifier) sounds much less unpleasant to the ear. For these amplifiers, the 1 dB compression point is defined as the input power (or output power) where the gain is 1 dB less than the small signal gain. Sometimes this nonlinearity is deliberately designed in to reduce the audible unpleasantness of hard clipping under overload.The problem of nonlinearity is most often solved with negative feedback.Linearization is an emergent field, and there are many techniques, such as feedforward, predistortion, postdistortion, EER, LINC, CALLUM, cartesian feedback, etc., in order to avoid the undesired effects of the non-linearities.NoiseThis is a measure of how much noise is introduced in the amplification process. Noise is an undesirable but inevitable product of the electronic devices and components, also much noise results from intentional economies of manufacture and design time. The metric for noise performance of a circuit is noise figure or noise factor. Noise figure is a comparison between the output signal to noise ratio and the thermal noise of the input signal.Output dynamic rangeOutput dynamic range is the range, usually given in dB, between the smallest and largest useful output levels. The lowest useful level is limited by output noise, while the largest is limited most often by distortion. The ratio of these two is quoted as the amplifier dynamic range. More precisely, if S = maximal allowed signal power and N = noise power, the dynamic range DR is DR = (S + N ) /N.1In many switched mode amplifiers, dynamic range is limited by the minimum output step size.Slew rateSlew rate is the maximum rate of change of the output, usually quoted in volts per second (or microsecond). Many amplifiers are ultimately slew rate limited (typically by the impedance of a drive current having to overcome capacitive effects at some point in the circuit), which sometimes limits the full power bandwidth to frequencies well below the amplifiers small-signal frequency response.Rise timeThe rise time, tr, of an amplifier is the time taken for the output to change from 10% to 90% of its final level when driven by a step input. For a Gaussian response system (or a simple RC roll off), the rise time is approximated by:tr * BW = 0.35, where tr is rise time in seconds and BW is bandwidth in Hz.Settling time and ringingThe time taken for the output to settle to within a certain percentage of the final value (for instance 0.1%) is called the settling time, and is usually specified for oscilloscope vertical amplifiers and high accuracy measurement systems. Ringing refers to an output variation that cycles above and below an amplifiers final value and leads to a delay in reaching a stable output. Ringing is the result of overshoot caused by an underdamped circuit.OvershootIn response to a step input, the overshoot is the amount the output exceeds its final, steady-state value.StabilityStability is an issue in all amplifiers with feedback, whether that feedback is added intentionally or results unintentionally. It is especially an issue when applied over multiple amplifying stages.Stability is a major concern in RF and microwave amplifiers. The degree of an amplifiers stability can be quantified by a so-called stability factor. There are several different stability factors, such as the Stern stability factor and the Linvil stability factor, which specify a condition that must be met for the absolute stability of an amplifier in terms of its two-port parameters.Electronic amplifiersMain article: Electronic amplifierThere are many types of electronic amplifiers, commonly used in radio and television transmitters and receivers, high-fidelity (hi-fi) stereo equipment, microcomputers and other electronic digital equipment, and guitar and other instrument amplifiers. Critical components include active devices, such as vacuum tubes or transistors. A brief introduction to the many types of electronic amplifier follows.Power amplifierThe term power amplifier is a relative term with respect to the amount of power delivered to the load and/or sourced by the supply circuit. In general a power amplifier is designated as the last amplifier in a transmission chain (the output stage) and is the amplifier stage that typically requires most attention to power efficiency. Efficiency considerations lead to various classes of power amplifier: see power amplifier classes.Vacuum tube (valve) amplifiersMain article: Valve amplifierThe glow from four Electro Harmonix KT88 brand power tubes lights up the inside of a Traynor YBA-200 guitar amplifierAccording to Symons, while semiconductor amplifiers have largely displaced valve amplifiers for low power applications, valve amplifiers are much more cost effective in high power applications such as radar, countermeasures equipment, or communications equipment (p.56). Many microwave amplifiers are specially designed valves, such as the klystron, gyrotron, traveling wave tube, and crossed-field amplifier, and these microwave valves provide much greater single-device power output at microwave frequencies than solid-state devices (p.59).2Valves/tube amplifiers also have niche uses in other areas, such asin russian military aircraft, for their EMP tolerance niche audio for their sound qualities Transistor amplifiersMain articles: Transistor, Bipolar junction transistor, Audio amplifier, and MOSFETThe essential role of this active element is to magnify an input signal to yield a significantly larger output signal. The amount of magnification (the forward gain) is determined by the external circuit design as well as the active device.Many common active devices in transistor amplifiers are bipolar junction transistors (BJTs) and metal oxide semiconductor field-effect transistors (MOSFETs).Applications are numerous, some common examples are audio amplifiers in a home stereo or PA system, RF high power generation for semiconductor equipment, to RF and Microwave applications such as radio transmitters.Transistor-based amplifier can be realized using various configurations: for example with a bipolar junction transistor we can realize common base, common collector or common emitter amplifier; using a MOSFET we can realize common gate, common source or common drain amplifier. Each configuration has different characteristic (gain, impedance.).Operational amplifiers (op-amps)Main articles: Operational amplifier and Instrumentation amplifierAn operational amplifier is an amplifier circuit with very high open loop gain and differential inputs which employs external feedback for control of its transfer function or gain. Although the term is today commonly applied to integrated circuits, the original operational amplifier design was implemented with valves.Fully differential amplifiers (FDA)Main article: Fully differential amplifierA fully differential amplifier is a solid state integrated circuit amplifier which employs external feedback for control of its transfer function or gain. It is similar to the operational amplifier but it also has differential output pins.Video amplifiersThese deal with video signals and have varying bandwidths depending on whether the video signal is for SDTV, EDTV, HDTV 720p or 1080i/p etc. The specification of the bandwidth itself depends on what kind of filter is used and which point (-1 dB or -3 dB for example) the bandwidth is measured. Certain requirements for step response and overshoot are necessary in order for acceptable TV images to be presented.Oscilloscope vertical amplifiersThese are used to deal with video signals to drive an oscilloscope display tube and can have bandwidths of about 500MHz. The specifications on step response, rise time, overshoot and aberrations can make the design of these amplifiers extremely difficult. One of the pioneers in high bandwidth vertical amplifiers was the Tektronix company.Distributed amplifiersMain article: Distributed AmplifierThese use transmission lines to temporally split the signal and amplify each portion separately in order to achieve higher bandwidth than can be obtained from a single amplifying device. The outputs of each stage are combined in the output transmission line. This type of amplifier was commonly used on oscilloscopes as the final vertical amplifier. The transmission lines were often housed inside the display tube glass envelope.Switched mode amplifiersThese nonlinear amplifiers have much higher efficiencies than linear amps, and are used where the power sav