专业英语.pptVIP

Analog and Digital 模拟电子和数字电子 Ideal Operational Amplifiers and Practical Limitations 　　　In order to discuss the ideal parameters of operational amplifiers, we must first define the terms, and then go on to describe what we regard as the ideal values for those terms. At first sight, the specification sheet for an operational amplifier seems to list a large number of values, some in strange units, some interrelated, and often confusing to those unfamiliar with the subject. The approach to such a situation is to be methodical, and take the necessary time to read and understand each definition in the order that it is listed. Without a real appreciation of what each means, the designer is doomed to failure. The objective is to be able to design a circuit from the basis of the published data, and know that it will function as predicted when the prototype is constructed.1 It is all too easy with linear circuits, which appear relatively simple when compared with today’s complex logic arrangements, to ignore detailed performance parameters which can drastically reduce the expected performance. 理想运算放大器和实践的局限性 为了讨论理想运算放大器的参数，我们必须首先定义，然后去描述什么我们视为理想值的那些条款。乍一看，一个运算放大器的规格表似乎列出大量的值，一些奇怪的单位，相关的，并常常混淆了那些不熟悉的题目。这种情况的办法是要有条理，并以阅读和理解每个定义它列出的顺序在必要的时间。没有什么每个方法的实际升值，设计者是注定要失败的。目标是要能够从公布的数据的基础上的电路设计，并知道它将函数作为预测当原型的构建。1很容易与线性电路相对简单，这似乎与今天的复杂逻辑的安排相比，忽略详细的性能参数可以大大减少预期的性能。 　　　Let us take a very simple but striking example. Consider a requirement for an amplifier having a voltage gain of 10 at 50?kHz driving into a 10 k? load. A common low-cost, internally frequency-compensated op amp is chosen; it has the required bandwidth at a closed-loop gain of 10, and it would seem to meet the bill. The device is connected, and it is found to have the correct gain. But it will only produce a few volts output swing when the data clearly shows that the output should be capable of driving to within two or three volts of the supply rails. The designer has forgotten that the maximum output voltage swing is se