[转]模集设计圣经100条

1.Capacitors and resistors have parasitic inductance, about 0.4nH for surface mount and 4nH for a leaded component.
1. 电阻跟电容都有寄生电感，贴片封装的大概0.4nH，插件的大概4nH.

2.Capacitors and resistors have parasitic inductance, about 0.4nH for surface mount and 4nH for a leaded component.
2.如果你不想通过在高带宽晶体管三个引脚中的至少两个引脚放置损耗元件的方法消除振荡.铁氧体磁珠会起到很好的作用.

3.When taking DC measurements in a circuit and they don"t make sense, suspect that something is oscillating.
3.对一个电路采用直流测试并且不起作用时,应该怀疑有元件在振荡.

4.Opamps will often oscillate when driving capacitive loads.
4.运放在驱动容性负载时经常会震荡。

5.The base-emitter voltage Vbe of a small signal transistor is about 0.65v and drops about 2mV/deg C. Vbe goes down with increasing temp.
5.小信号晶体管的基-射极电压Vbe大约是0.65伏特，大约以2毫伏/摄氏度的速度降低。Vbe随着温度的升高而降低。

6.Multiply 0.13nV by the square root of the ohmic value of a resistor to find the noise in a 1Hz bandwidth. Then multiply by the square root of the BW in Hz gives the total noise voltage.
6.电阻阻值的平方根，乘以0.13纳伏，可以得到1赫兹带宽的噪声。再乘以以赫兹为单位的带宽的平方根，可以得到总噪声电压。

7.Johnson noise current goes down with a increase in resistance.
7.Johnson噪声电流随着电阻的增加而降低.

8.The impedance looking into the emitter of a transistor at room temp is 26Ohm/Ie in mA
8.室温下晶体管射极阻抗为26Ohm/mA

9.All amplifiers are differential in that they are referenced to ground somewhere.
9.所有的放大器都是相对于某个地电平的差分放大

10.Typical metal film resistor has a temp coef of about 100 ppm/deg C
10.典型的金属薄膜电阻具备100 ppm/deg C的温度系数

11.The input noise voltage of a quiet op amp is 1nv/sqrt(Hz) but there are plenty available with 20nV/sqrt(Hz). Op amps with bipolar front-ends have lower voltage noise and higher current noise than those with FET front-ends
11.低噪音运放的输入噪声电压可以达到1nv/sqrt(Hz) ，但是我们大量用到的运放具有20nV/sqrt(Hz)的输入噪音。双极晶体管结构比FET结构的运算放大器具备更地的电压噪声和更高的电流噪声

12.Using an LC circuit as a power supply filter can actually multiply the power supply noise at the filter"s resonant frequency. Use inductor with low Q to overcome this.
12.用LC滤波器对电源滤波将会增加电源在滤波器谐振频率点上的噪声，通过选择低Q的电感可以有效克服这一点。

13/ Use comparators for comparing and op amps for amplifying and don"t even think of mixing the two.
（用比较器进行比较，用运放进行放大，千万不要搞混。

14.Ceramic caps with any other dielectric other than NPO should only be used for bypass applications.
14. 除高频瓷片电容外的瓷片电容仅可用作旁路电容

15.An N-channel enhancement-mode FET needs +ve voltage on the gate-source to conduct form drain-source.
15.n沟道增强型mosfet需要在gate-source 间接入正电压来控制drain-source间的电流Ids

16.Small signal JFETS work very well as low-leakage diodes by connecting drain & source together in log current-to-voltage converters and low leakage input protection. Small signal bipolars with b-c tied together will also make nice low-leakage diodes.
16.JFETS短接源漏极在小信号电流-电压转换和输入保护方面具备和低泄漏二极管媲美的特性，小信号测量中晶体管B-E极短接也相当于一个优异的低泄漏二极管。

17.With low pass filter use Bessel for least amount of overshoot in the time domain, and Cauer (or elliptic) for fastest rolloff in the freq domain.

17.设 计低通滤波器时选用贝塞尔型可以使时域较平坦，没有太多过冲，选用切比雪夫可以提高截止频率的陡峭性。

18.dB is always 10 times the log of the ratio of 2 powers.
18.分贝是10*lg的比值。

19.At low frequencies, the current in the collector of a transistor is in phase with the applied current at the base. At high frequencies the current at the collector lags by 90deg. You must appreciate this simple fact to understand high frequency oscillators.
19.低频情况下，晶体管集电极电流与基极电流同相，但在高频情况下，集电极电流相位上滞后90度，这有助于你理解高频振荡。

20.The most common glass-epoxy PCB material (FR4) has a dielectric constant of about 4.3 To make a trace with a characteristic impedance of 100 Ohm, use a trace thickness of about 0.4 times the thickness of the board with a ground plane on the opposite side. For a 50Ohm trace make it 2 times the thickness.
20.PCB应用最普通的FR4材料的介质常数大约为4.3，印制版线为得到100欧的特征阻抗需要的线宽为PCB板（背面覆铜）厚度的0.4倍，50欧的阻抗需要线宽为板后的2倍。--线长呢？不解

21.If you need a programmable dynamic current source, find out about operational transconductance amps. Most of the problem is figuring out when you need a programmable dynamic current source.
21.当你用跨导运算放大器作为可编程动态电流源时你会发现很多问题。

22.A CMOS output with an emitter follower can drive a 5V relay nicely as the relays normally have a must-make spec of 3.5V. This saves power and require no flyback components.
22.CMOS输出配合一个射极跟随器可以很好的驱动一个5V工作的继电器（必须是3.5V以上才能正常工作），这样节省了功率并不需要反馈元件。

23.Typical thermocouple potential is 30uV/degC. Route signals differentially, along the same path, avoid temp gradients. DPDT latching relays won"t heat up when multiplexing these signals.
23.典型的热电偶电位是 30uV/degC，布线是差分信号要尽量走同样的路径避免差分线上产生温度梯度。当需要切换这些信号时，双刀双掷常闭继电器可以避免切换过程中产生的热量，影响热电偶温度测量的精度。

24.You SHOULD be bothered by a design that looks messy, cluttered or indirect. This uncomfortable feeling is one of the few indications that there"s a better way.
24.你可能会直接或间接的感到设计的电路感混乱不堪，这种不好的感觉其实是一种很宝贵的暗示，那就是那肯定还有一直能够更好的设计路径

25.Avoid drawing any current from the wiper of a potentiometer. The resistance of the wiper contact will cause problems (local heating, noise offsets etc.)
25.避免任何的电流都可以从电位器分压而得，电位器相关的阻抗可能回导致一些问题，如局部加热，噪声，偏移等

26.Most digital phase detectors have a deadband where the analog output does not change over the small range where the 2 inputs are coincident. This often-ignored fact has helped to create some very noisy PLL"s (Use a high val bleeding resistor to always ensure current flow in the deadband)
26.数字鉴相器有一个死区，就是模拟输出在一个很小的范围内（双端输入一致的情况下）不改变，这个经常被忽视的事实很容易造成PLL噪声非常大，用一个大阻值的旁漏[泄漏]电阻确保电流注入死区。

27.The phase noise of a phase-locked VCO will be at least 6dB worse than the phase noise of the divided reference for each octave between the comparison frequency and the VCO output frequency. Avoid low-comparison frequencies.

28.You can almost always determine the leads of a bipolar transistor with an ohm meter. b-e and b-c junctions will measure like a diode with the b-c junction reading slightly lower than the b-e junction when forward biased.
28.通过电阻表可以分辨三极管的极性。发射结和集电结跟二极管差不多，集电结正向偏置时的读数要稍小于发射结。

29.For low distortion, the drains (or collectors) of a differential amp”s front-end should be bootstrapped to the source (or emitter) so that the voltages on the part are not modulated by the input signal.

30.If your design uses a $3 op amp, and you will be making a thousand of them, you have just spend $3000. Are you smart enough to figure out how to use a $.30 op amp instead?
30.3元一个的运放生产一千个就是3000元。为了节约成本，可以想办法用0.3元的运放替代。

31.The Q of an LC tank circuit is dominated by the losses in the inductor in terms of series R. Q=omega.L/R

32. Leakage current doubles for every 10degC increase in temp.
32.温度每提高10度，漏电流就扩大一倍。

33.When inputs to most JFET op amps exceed the common-mode range for the part, the output may reverse polarity. This artifact will haunt the designers of these parts for the rest of their lives, as it should!

34.Understand the difference between "make-before-break" and "break-before-make" when you specify switches.
34.在选择开关时，弄清楚先接后断和先断后接的区别。

35.3 Terminal voltage regulators in the TO-220 packages are wonderful parts. They are cheap, rugged, thermally protected and very versatile. Use them virtually any place where you need a protected power transistor. They also make nice AM power-modulators.
35.TO-220封装的三端稳压器是非常棒的电子器件。它们便宜、坚固、具有热保护功能、并且有多种用途。在你想要用到电源保护功能的地方几乎都能看到它。它们也可做为优良的功率调幅器

36.Use step recovery diode where you need fast edges under 100pS (hot-carrier is even faster)

37.The old 723 regulator is still one of the lowest noise regulators around! (2.5uVrms 100Hz-10k)
37.略显老旧的723仍然是噪声最低的稳压器之一 (2.5uVrms 100Hz-10k) 。

38.You can make a very simple oscillator with one diac, cap and a resistor.
38.你可以用一个双向触发二极管、电容和一个电阻制作一个非常简单的振荡器

39.NPN transistors are normally superior to their PNP counterpart in performance.
39.NPN管通常比对应的PNP管性能好。

40.Typical spec in some databooks should read “Seen it once”. Always work with the worst spec of the part when doing a design. 40.对于有些数据手册中的典型参数,我们应该只是看看而已.在作设计的时候,应该总是按照最坏参数来考虑.

41.Don”t just copy circuits from application notes without understanding completely how it operates, and the reason for the choice of values.
41.不要在没有完全理解电路的运行原理和元件的取值原因的情况下,就从应用手册中直接照抄电路.

42.Dealing with crystals, make sure you understand the difference between series and parallel resonant. In a circuit, crystal frequency can generally be slightly lowered by placing a inductor in series and increased by a capacitor in series.
42.在处理晶振的时候,确定你理解了串联谐振和并联谐振的区别.在电路中,串联一个电感会使晶振的频率产生轻微的降低,串联一个电容会使晶振的频率产生轻微的升高.

43.Power MOSFETS on-resistance will have a -ve temp coef and not +ve at low current levels. This is important to remember when paralleling devices.
43.在低电流的情况下，功率MOSFET的导通电阻拥有负温度系数。对于并联器件的时候这一点尤为重要。

44.Lowest noise figure of a RF transistor is not normally where the input
44.最低噪声的射频晶体管作为输入时（产生的噪声）也是非比寻常的。

45.Many un-stable RF devices can be made stable by loading the input or the output by a simple resistor, either in series or parallel.
45.许多不稳定的射频器件，可通过加载一个简单的电阻到输入或输出端使之稳定，无论串联或是并联。

46.You trade gain for bandwidth.
46.你用增益交换带宽

47.Push-pull power invertors using bipolars are risky and can saturate the core because of hysteresis stepping (use power fets)
48.The Al value of a core will increase up to 50% or more under current transients.
49.Be aware of leakage inductance when switching. V=L(dI/dt)
50.The harder you turn-on a power transistor, the longer it will take to turn off.( the part where you burn the joules in the device)

51.Always remember the Miller guy. 51.永远记住米勒这个家伙(三极管的米勒电容)。

52.In fault-finding a circuit, don”t overlook the obvious. (is there power?)
53.What is a ground loop, and how to avoid it.
53.地回路是什么？如何避免它？

54.120 is a better number than 240 when using LM3XX type adjustable regulators.
54.在使用LM3XX系列的可调稳压器的时候，120是一个比240好的数字。像LM317要求的最小输出电流是5ma，所以一般推荐1.25V处使用240欧姆调压电阻，这样保证空载时也满足最小电流要求。
使用120欧姆电阻空载电流更大可能在电压精度，负载调整率上比240欧姆更好（10ma效果好于5ma，再大效果就差不多了）

55.The lower comparator in the old 555 may have quite a long storage time.
56.ZERO-ESR caps may do more harm than good.
57.A correctly configured audio power amplifier will give more distortion in Class-AB, not less, because of the abrupt gain changes inherent in switching from A to B every cycle.

58.Be a STAR when it comes to ground matters.
58.当涉及到地的时候，使用星型连接。

59/ Know when you need to use a Zobel network.

60.Use current mirrors and mirror your current.
60.使用镜像电流源反映电流。

61.Heatsink eff decreases with height above sealevel.
61.散热片的效率与其在丝印面上的高度成正比。

62.A matt-black heatsink is much better than a shiny one.
62.黑色的散热片比白色的好。

63.Ignoring secondary breakdown can be costly.
63.忽略二次击穿的代价会很高。

64.Understand fuses and fuse ratings, fast and slow. Do you know when to use a semiconductor-fuse?
64.掌握保险丝和保险丝的等级，动作快还是慢。什么时候用半导体保险丝。

65.Charge balancing resistors are a must when stacking serie-parallel high voltage capacitor banks.
65.串并联高压电容器（高电压大容量电容器）必须使用充电电阻。

66.You must understand DC-restoration otherwise you will have a hard time designing Z-modulation in CRT circuits.
66.必须懂得DC-restoration ，否则在设计CTR Z调制电路时犯难。

67.Display 6 vert div low freq on a scope, increase the freq (make sure the source is constant amplitude) until display drops to 4.2 div. That is the true 3dB BW of the scope. (scope-source impedance should be matched)
67.在示波器上用6格的幅度表示低频，慢慢增大频率（确保信号源幅值不变）；当信号降到4.2格时，就得到了示波器3dB带宽（输入阻抗要匹配）

68.Doing a measurement with your DMM in the ACV position on your DC circuit will give a quick indication of any excess ripple on the supply when you don"t have a scope at hand.
68.当你没有示波器在时，使用数字万用表的门交流电压档可以很容易到直流电路的电源纹波值。

69.Dly timebase on a scope is very useful once you figured out when, why and how to use it.
69.示波器上的时基延时（好像是触发延时吧）非常有用；一旦你知道什么时候使用，为什么使用，怎么样使用时基延时的时候。

70.Know what to expect before you measure, otherwise any measurement is meaningless.
70.在你测量之前要明白会发生什么事情，否则任何测量是没有意义的。

71.Op amps. Output will swing in the direction that will force the inv-input level to try come closer to the non-inv input level.

72.Understand virtual ground, slew-rate, CMRR and PSRR. (CMRR decrease with increase in freq)
72.理解虚地、摆率、共模抑制比和电源抑制比.(共模抑制比随着频率的升高而下降)

73.Making measurements near a spec-analalyzer”s noise floor will give 3dB errors. 73.在频谱仪的噪声层附近测量会引起3dB的误差

74.Understand the phase-noise limitations of the analyzer when making such measurements on oscillators. 74.测量振荡器时，理解相位噪声对仪器的限制

75.In a LC oscillator add some C with -ve temp coef to cancel the +ve temp coef of the L for min drift with temp. 75.在LC振荡器种，加入具有负温度系数的电容来抵消电感的正温度系数，减小温飘

76.Less drift will result from making C with a few parallel caps, to reduce the heating effect of the oscillating current when spread out over a larger plate area.
77.You will get more tuning range with the same LC combination in a Clapp than in a Colpitts circuit. 77.使用相同的LC组合，使用克拉普振荡器可以获得比考比茨振荡器更大的调谐范围

78.High-Q tuned LC filters will have more insertion loss. 78.高Q值的LC滤波器有更大的接入损耗

79.Williams”s Rule (Guru at Linear Tech) for precision op amp circuits: ” Always invert (except when you can”t)” 79.高精度运放放大电路的 威廉姆法则（来自Linear Tech的大师）：“永远反向（除非在你做不到的时候）”

80.Cuk is not a kind of locomotive. 80.库克直流斩波电路并不是一种（机车？我的理解是不能简单的当成把低压电源变成高压电源，因为库克电路不能提高带负载能力）

81.If you don't know how to make a design better, find out what makes it worse.
81如果您不知道如何设计更好，那就找出是什么使情况变得更糟。

82.Sometimes you know just enough to be dangerous.
82.有时候你的经验会误导你

83.Impedance will reflect back as the square of the turns ratio.
83.阻抗会以匝数比之平方反射回去(阻抗变换)

84.If you could design a component with the characteristics of a finger it could cure many design problems and you will be rich.
84.如果你能使用手指的特点（OMG召唤英语帝，我晕了，是徒手的意思吗？）设计一个元件，那么这将会改正设计中的许多错误，你就会变得富有了（你赚的就多了）（我理解的是，如果你有徒手设计计算一个元件的功力了，就进阶为高手了）

85.Get nervous when the customer you are trying to help doesn"t even have a scope.
85.如果你尽力想要帮助的顾客一点都不理解（你说的东西），那么要从你自身找原因（好吧，意译的比较严重）

86.Specs quoted by reps always exceed those by Engineering.
86.推销员给出的规格总是优于工程师所给出的

87.A bad (Engineer) workman always blames his tools.
87.差劲的工程师总是怪罪他的工具

88.Don"t believe everything that a SPICE program spits out.
88.永远不要相信任何SPICE仿真给出的结果

89.It is easy to get the color code of a 1kOhm and 12Ohm resistor mixed up when you are in a hurry.
89.匆匆忙忙时容易把12欧的色环电阻与1K的色环弄混

90.I bet one could write a thesis about the ability of probes to get tangled-up on a bench.
90.我打赌一个能写一篇关于探针能力的论文的人，在工作台上将无限纠结……

91.DMM can upset sensitive circuits from noise generated inside it.

92.When probing directly on a crystal of a uP, use 10kOhm or so resistor in series with the probe tip to prevent loading from stopping the osc.
92.如果要直接在晶体引脚上面测试（比如万用表表笔或示波器探针），应该串联一个10K欧姆的电阻再测试，防止外部干扰窜入振荡回路或者说破坏原来的振荡状态。

93.It is easier to see what is happening on the ports using a scope when you trigger one chan against the cpu clock.
93.有时候,当你试着用CPU的反相钟来触发一个示波器通道时，也许更容易发现“端口”发生了什么故障

94.National Semiconductor once made a bad op amp many years ago that some Engineers referred to it as "Jelly Beans"
94.国家半导体公司很多年前生产过一颗坏运放，有些工程师称之为“果冻豆”。（寓意：要有怀疑的眼光看问题？）

95.The moment you can start to notice distortion on an oscilloscope it is already way past being acceptable.
95.当你开始注意到示波器上的失真，其实它已经是在过去就被接受了的方式。

96.Be big enough to say "I don"t know", people will respect you more.
96.大声说：“我不知道”，人们将更尊重你。

97.The best designer is often working in the marketing department.
97.有时好的设计，要倾听下市场给的建议
98.Some remarkable discoveries/inventions were made by people that knew very little about the subject. Don't fall into a groove in you thinking process.
98.作出某些显着的发现/发明的人，其实他们对于这个课题了解并不多。不要在你的思考过程中养成一种习惯。
99.The Peter-Principle : Everybody will be promoted up his own level of incompetence.
99.彼得原理:“(在一个等级制度中)人们趋向于上升到他所不能胜任的地位”。

100/ END-Enjoy