Lesson 13 Function Generators电子技术专业英语教程.ppt

1、Lesson 13 Function Generators 电子技术专业英语教程冯新宇 主编 电子工业出版社 ,Unit5 Electronic Instruments,2020/10/10,电子技术专业英语教程,2,Lesson 13 Function Generators,Backgrounds Text tour Language in use Vocabulary Structure Reading/writing techniques,2020/10/10,电子技术专业英语教程,3,Terminology odd harmonics 奇次谐波 triangle wave 三角波 pe

2、ak deviation 峰值偏差 angular frequency 角频率 sawtooth wave 锯齿波,Backgrounds,2020/10/10,电子技术专业英语教程,4,Terminology bandlimite 带限 function generators 函数发生器 single-shot 单次激发 aliasing distortion 混淆（折叠）失真,Backgrounds,2020/10/10,电子技术专业英语教程,5,Text tour,Outline What is a Function Generator? The basic principles of

3、Function Generator The type of output connector More advanced function generators Triangle wave Sine wave Sawtooth wave,2020/10/10,电子技术专业英语教程,6,What is a Function Generator?,A function generator is a piece of electronic test equipment or software used to generate electrical waveforms. These waveform

4、s can be either repetitive, or single-shot in which case some kinds of triggering source are required (internal or external). Another type of function generator is a sub-system that provides an output proportional to some mathematical function of its input.,a function generator,2020/10/10,电子技术专业英语教程

5、,7,The basic principles of Function Generator,Analog function generators usually generate a triangle waveform as the basis for all of its other outputs. The triangle is generated by repeatedly charging and discharging a capacitor from a constant current source. This produces a linearly ascending or

6、descending voltage ramp. As the output voltage reaches upper and lower limits, the charging and discharging are reversed using a comparator, producing the linear triangle wave. By varying the current and the size of the capacitor, different frequencies may be obtained.,2020/10/10,电子技术专业英语教程,8,The ba

7、sic principles of Function Generator,A 50% duty cycle square wave is easily obtained by noting whether the capacitor is being charged or discharged, which is reflected in the current switching comparators output. Most function generators also contain a non-linear diode shaping circuit that can conve

8、rt the triangle wave into a reasonably accurate sine wave. It does so by rounding off the hard corners of the triangle wave in a process similar to clipping in audio systems.,2020/10/10,电子技术专业英语教程,9,The type of output connector,The type of output connector from the device depends on the frequency ra

9、nge of the generator. A typical function generator can provide frequencies up to 20 MHz and uses a BNC connector, usually requiring a 50 ohm or 75 ohm termination. Specialized RF generators are capable of gigahertz frequencies and typically use N-type output connectors.,a BNC connector,a N-type outp

10、ut connector,2020/10/10,电子技术专业英语教程,10,More advanced function generators,More advanced function generators use Direct Digital Synthesis (DDS) to generate waveforms. Arbitrary waveform generators use DDS to generate any waveform that can be described by a table of amplitude values.,a DDS function gene

11、rator,2020/10/10,电子技术专业英语教程,11,Triangle wave,A triangle wave is a non-sinusoidal waveform named for its triangular shape. Like a square wave, the triangle wave contains only odd harmonics. However, the higher harmonics roll off much faster than in a square wave.,Figure 13-1 A bandlimited triangle wa

12、ve pictured in the time domain (top) and frequency domain (bottom). The fundamental is at 220 Hz (A2).,2020/10/10,电子技术专业英语教程,12,Triangle wave,It is possible to approximate a triangle wave with additive synthesis by adding odd harmonics of the fundamental, multiplying every (4n1) th harmonic by 1 (or

13、 changing its phase by ), and rolling off the harmonics by the inverse square of their relative frequency to the fundamental. This infinite Fourier series converges to the triangle wave:,2020/10/10,电子技术专业英语教程,13,Sine wave,The sine wave or sinusoid is a function that occurs often in mathematics, musi

14、c, physics, signal processing, audition, electrical engineering, and many other fields. Its most basic form is: This describes a wavelike function of time (t) with: peak deviation from center= A (aka amplitude); angular frequency , (radians per second); phase = . When the phase is non-zero, the enti

15、re waveform appears to be shifted in time by the amount / seconds. A negative value represents a delay, and a positive value represents a head-start.,2020/10/10,电子技术专业英语教程,14,Sine wave,The sine wave is important in physics because it retains its waveshape when added to another sine wave of the same

16、frequency and arbitrary phase. It is the only periodic waveform that has this property. This property leads to its importance in Fourier analysis and makes it acoustically unique.,Figure 13-2 The graphs of the sine and cosine functions are sinusoids of different phases,2020/10/10,电子技术专业英语教程,15,Sawto

17、oth wave,The sawtooth wave (or saw wave) is a kind of non-sinusoidal waveform. It is named a sawtooth based on its resemblance to the teeth on the blade of a saw. The convention is that a sawtooth wave ramps upward and then sharply drops. However, there are also sawtooth waves in which the wave ramp

18、s downward and then sharply rises. The latter type of sawtooth wave is called a reverse sawtooth wave or inverse sawtooth wave. As audio signals, the two orientations of sawtooth wave sound identical.,Firgure 13-3 A bandlimited sawtooth wave pictured in the time domain (top) and frequency domain (bo

19、ttom). The fundamental is at 220 Hz (A3).,2020/10/10,电子技术专业英语教程,16,Sawtooth wave,The piecewise linear function based on the floor function of time t, is an example of a sawtooth wave with period 1. A more general form, in the range 1 to 1, and with period a, is This sawtooth function has the same ph

20、ase as the sine function.,2020/10/10,电子技术专业英语教程,17,Sawtooth wave,A sawtooth can be constructed using additive synthesis. The infinite Fourier series converges to an inverse sawtooth wave. A conventional sawtooth can be constructed using,2020/10/10,电子技术专业英语教程,18,Sawtooth wave,In digital synthesis, th

21、ese series are only summed over k such that the highest harmonic, Nmax, is less than the Nyquist frequency (half the sampling frequency). This summation can generally be more efficiently calculated with a Fast Fourier transform . If the waveform is digitally created directly in the time domain using

22、 a non-bandlimited form, such as y=x-floor(x), infinite harmonics are sampled and the resulting tone contains aliasing distortion.,2020/10/10,电子技术专业英语教程,19,Vocabulary Acquisition stimulus margin evaluation ancillary brief Structure Reading/writing techniques,Language in use,2020/10/10,电子技术专业英语教程,20,

23、Vocabulary,2020/10/10,电子技术专业英语教程,21,Acquisition in dictionary,The act of acquiring. 获得，取得 Something acquired, especially an addition to an established category or group. 获得物 The process of locating a satellite, guided missile, or moving target so that its track or orbit can be determined. 搜索，探测,2020

24、/10/10,电子技术专业英语教程,22,Acquisition in text,An acquisition instrument usually an oscilloscope or logic analyseris probably the first thing that comes to mind when you think about making electronic measurements. 当进行电子测量时，人们首先想到的很可能是一件采集仪器通常是示波器或逻辑分析仪。,2020/10/10,电子技术专业英语教程,23,Acquisition in use,aircraft

25、 target acquisition 空中目标的搜索 high-speed data acquisition 高速数据采集 language acquisition 语言习得 technique acquisition 技术引进,2020/10/10,电子技术专业英语教程,24,Stimulus in dictionary,Something causing or regarded as causing a response. 刺激因素 An agent, an action, or a condition that elicits or accelerates a physiologica

26、l or psychological activity or response. 刺激物,2020/10/10,电子技术专业英语教程,25,Stimulus in text,The toolset for digital design characterization differs from its counterpart in analog/mixed signal design, but both must include stimulus instruments and acquisition instruments. The signal source, or signal gene

27、rator, is the stimulus source that pairs with an acquisition instrument to create the two elements of a complete measurement solution. 用于数字设计特性评价的测量仪器和用于模拟/混合信号设计的测量仪器是不一样的，但两者一定都包含激励信号产生仪器和信号采集仪器。信号源（或信号发生器）和采集仪器是构成一个完整测量解决方案的两大基本组成部分。,2020/10/10,电子技术专业英语教程,26,Stimulus in use,under the stimulus of

28、this hope Light is a stimulus to growth in plants.,2020/10/10,电子技术专业英语教程,27,Margin in dictionary,An edge and the area immediately adjacent to it; a border. 边缘，边界 The blank space bordering the written or printed area on a page. 空白 A limit in a condition or process, beyond or below which something is

29、no longer possible or acceptable: 极限 the margin of reality has crossed the margin of civilized behavior.,2020/10/10,电子技术专业英语教程,28,Margin in dictionary,An amount allowed beyond what is needed: 余地 A measure, quantity, or degree of difference: 差数 The minimum return that an enterprise may earn and still

30、 pay for itself. 边际收益 The border of a leaf. 树叶的边缘,2020/10/10,电子技术专业英语教程,29,Margin in dictionary,In telegraphy, a measure of the ability of the receiving apparatus to copy with timing errors in the received signal. In printing, the space surrounding the type area, comprising head, tail, back and for

31、edge.,2020/10/10,电子技术专业英语教程,30,Margin in text,To cite another example, engineers must characterize their emerging designs to ensure that the new hardware meets design specifications across the full range of operation and beyond. This is known as margin or limit testing. 举另外一个例子。为了确保新硬件在整个操作范围及该范围之外满

32、足性能设计要求，工程师们必须对即将完成的设计进行特性评价。这就是所谓的“边缘测试或极限测试”。,2020/10/10,电子技术专业英语教程,31,Margin in use,by a comfortable margin 以较大的多数 by a narrow margin 以微弱多数 by a . margin 以.之差,2020/10/10,电子技术专业英语教程,32,Margin in use,binding margin 装订边 continental margin 大陆边缘 current margin 工作电流范围, 电流容限 design margin 设计余量 error mar

33、gin 误差容限,2020/10/10,电子技术专业英语教程,33,Margin in use,low level noise margin 低电平噪声容限 magnitude margin 幅值裕度 noise margin 噪声容限, 噪声安全系数 nominal margin 标称容限 peak margin 峰值容限,2020/10/10,电子技术专业英语教程,34,Evaluation in dictionary,A process to determine whether or not an item of hardware or software can perform a pa

34、rticular required function or to determine which of two or more items can perform the function best. 评价；鉴定 A process to reduce an expression to its simplest form or a single value. 计算，求值,2020/10/10,电子技术专业英语教程,35,Evaluation in text,A signal source is nothing less than the cornerstone of almost any instrumentation setup used in hardware design, debug, or evaluation projects 信号源是用于硬件设计、调试、评价工程中的几乎任何一种测量配置的基础。,2020/10/10,电子技术专业英语教程,36,Evaluation in use,accomplishment evaluation 学业成绩评定 hazard evaluation 危害评价 loss evaluation 损耗估算 evaluation of determi