外文翻譯--運(yùn)算放大器的原理和應(yīng)用

1、Operational amplifier theory and applications1 the principle of op-amp Op amp is the most widely used of a device, although the different structure of different operational amplifier, but the external circuit, its characteristics are the same. Op amp is usually 4 parts, bias circuits, input stage, i

2、ntermediate-level, output level, which is generally used input stage differential amplifier circuit (inhibitory power), the middle class in general the use of active load circuit loads the total radio (increase the magnification), the complementary output stage generally symmetrical output stage cir

3、cuit (drive circuit to increase the capacity of the load), here is a brief introduction about the realization of the specific complex. Industries, an operational amplifier used to measure the performance of many of the indicators, the actual operational amplifier is generally believed that the close

4、r the ideal op amp, the better, the classroom involved, we are only asking the equivalent input resistance of infinity, infinite open-loop gain, In fact, there are many other indicators, I will, are you a brief introduction, the performance of operational amplifiers including the five indicators, op

5、en-loop differential-mode voltage amplification factor, the maximum output voltage, differential-mode input resistance, output resistance, common mode rejection ratio CMRR. (Open-loop differential-mode is the magnification on the integrated delivery without additional feedback loop in case of differ

6、ential-mode voltage amplification. Maximum output voltage is saying that it refers to a certain voltage, the integrated operational amplifier is not the largest output voltage distortion peak - peak. differential-mode input resistance reflects the size of integrated operational amplifier input diffe

7、rential-mode input signal to obtain the current size of the source. requiring the greater the better. reflect the size of the output resistance of an integrated transport on the small-signal output load capacity. CMRR shown on the integrated operational amplifier common-mode rejection of input signa

8、ls, which is defined with the differential amplifier circuit. CMRR the better.)Figure 1 op-amp characteristic curveFigure 2 op-amp input and output terminal mapFigure 1 is the characteristic curve of amplifier is generally used only the linear part of curve. As shown in Figure 2. U-corresponding to

9、the terminal -, when the importation of Canadian U-separate from the terminal, the output voltage and input voltage U-RP, the RP-call input. U + corresponding to the terminal +, when the input U + separate from the client to join, the output voltage and U + with the phase, so called in-phase input.

10、Output: U0 = A (U +-U-); A known as the op amps open loop gain (open-loop voltage amplification factor) In the practical application of often idealized op amp, this is because generally speaking, the input resistance OPAMP great open-loop gain, output resistance is very small, can be regarded as ide

11、al, it can be : Ri , Ro 0, A . By A , be U + U-, a result similar to the two inputs can be seen as a short-circuit (referred to as the virtual short), if the input termination in the same direction, the reverse input and almost the same potential (referred to as virtual land). By Ri , we can see tha

12、t similar to the input circuit is equal to 0, it can be seen as the input circuit (known as the virtual shutdown).2 Application of Operational Amplifiers Here only the application of the ideal operational amplifier, the actual op amp can be seen as similar to an ideal operational amplifier. Applicat

13、ion of operational amplifiers is very broad, here we only talk about the op-amp with some focus on other components of the computing circuit. Application of circuit operation in terms of comparison with other more extensive, and easy to understand some of them. Computing the ratio of the circuit inc

14、luding the circuit, and differential circuit, integro-differential circuit, and the index of the number of computing circuit. 1. The proportion of the circuit: The proportion of the so-called circuit is proportional to the input signal amplification circuit, the ratio of the reverse circuit is divid

15、ed into the proportion of the circuit, the circuit with the phase ratio, the ratio of differential circuit. (1) reverse the ratio of the circuit: Reverse the ratio of the circuit shown in Figure 3, the input signal input by adding RP, there are Figure 3 the ratio of the reverse circuit schematicsFig

16、ure 4 with the ratio of circuit schematics=0 =0Know from Kirchhoffs law:= （-）/=（-）/=Thus know that the output voltage U0 and the ratio of input voltage Ui said the relationship between the opposite direction, changing the ratio of coefficients, namely, two resistors of resistance to change can chang

17、e the value of output voltage. Reverse the ratio of operational amplifier circuits for the performance of a certain performance requirements, such as the input signal to a certain load capacity requirements.(2) the ratio of the circuit in the same direction (Figure 4): With the reverse ratio of the

18、circuit is essentially similar, apart from a section of ground in the same direction is the reverse input from= =得：/=(-)/SO: =So as long as the coefficient of change in the proportion of the output voltage can be changed, and U0 and Ui the same direction, of course, with the proportion of the circui

19、t is to have a certain requirements, such as the integrated operational amplifier of the common mode rejection ratio requirements. (3) the ratio of differential circuit (Figure 5):=Input signal, respectively, added to the RP-phase input and input, the specific steps and not in the first two are deri

20、ved almost And in the end be: From this we can see that it is actually completed: two of the input differential signal operation. 2. And the difference circuit: And poor use of the circuit is a relatively wide range of circuits, where the three circuits on the move: Reverse summation circuit to sum

21、the same circuit, and differential circuits. (1) reverse summation circuit and summation circuit in the same direction: Only difference is that the input signal by adding a reversed-phase input with input phase difference, reverse-sum circuit in Figure 6, with the summation circuit in Figure 7. By K

22、irchhoffs current law, reverse summation circuit output voltage and input voltage relationship,= Figure 5 the proportion of the circuit differential circuit Figure 6 Reverse summation circuit schematicsFigure 7 with the circuit diagrams and circuitWith the summation circuit output voltage and the re

23、lationship between the input voltage as follows:=Although the comparison between the two similar, but different, the reverse sum of the characteristics of the circuit with the same RP-circuit ratio. It can be very convenient for the input resistance of a circuit to change the relationship between th

24、e proportion of the circuit without affecting the relationship between the proportion of other routes. And with the application to the summation circuit is not very extensive, mainly because of its better regulation of RP-sum circuit, and its large common-mode input signal. (2) and the difference ci

25、rcuit:Its circuit diagram is shown in Figure 8. The function of this circuit is Ui1, Ui2 carried out by RP-summation of Ui3, Ui4 sum to the same direction, and then superimposed the results obtained and the poor, and his relationship between input and output voltage as follows:=Figure 8 and the diff

26、erential circuit schematicsAs the use of an integrated circuit operational amplifier, and its calculation and the circuit resistance is not easy to adjust, so we used the composition of the secondary operational amplifier integrated circuit and poor. Its circuit diagram as shown in Figure 9, its the

27、 relationship between input and output voltage is:= Figure 9 composed of two integrated operational amplifier circuit schematics and poorIts former level after the level does not affect (in the ideal of integrated operational amplifier), which is very convenient calculation. 3. Integral and differen

28、tial circuit: The above components used are basically resistive element, if one side of the resistor capacitor replaced, then the results will become integral circuits and differential circuits. (1) integral circuit: The circuit shown in figure 10, it can achieve integration and production of comput

29、ing, such as triangular waveform. Integral operation is: the output voltage and input voltage relations were integral. It is the use of capacitive charge and discharge operations to achieve integration, and its input and output voltage relationship:=One: that the initial capacitor voltage at both en

30、ds. If the circuit input voltage waveform is a square, then have a triangular waveform output. (2) differential circuit: Differential circuits and the difference between circuit points just swap the location of resistors and capacitors. Differential is the integral of the inverse operation, its outp

31、ut voltage and input voltage relations showed differential. Circuit diagram shown in Figure 11: its input and output voltage relationship:=Circuit schematics Figure 10 point Figure 11 Differential circuit schematics4. And the index calculation on the number of circuits: Circuit used for a number of

32、diodes, diode characteristics of the most important is one-dimensional conductivity. In the circuit, the current only flows from the diode cathode, anode flow, it is the realization of the characteristics and indicators of the number of circuits. (1) of the number of operation circuits:=Logarithm co

33、mputing circuit output voltage and input voltage was logarithmic function. RP we use the ratio of Rf diode circuit that is formed instead of the number of operations on the circuit. Circuit diagram shown in Figure 12. He relationship between the output of the input voltage isFigure 12 Logarithm comp

34、uting circuit schematicsFigure 13 Index computation circuit schematicsIn fact, transistor can also be used in place of diodes, the principle is the same, in addition to a multi-line connections. (2) index operation circuits:=Index calculation on the number of circuits and circuit computing the diffe

35、rence is only diodes and resistors to each other location, the index is the number of operation circuits computing inverse operation, the index of the diode operation circuits (three tubes) and the resistance R of the exchange can be. Circuit as shown in 13 Its input and output voltage relationshipU

36、se of computing as well as index number and the proportion of poor operation and circuit can be composed of multiplication or division operation circuits and other non-linear operation circuit, will no longer be described here.中文翻譯：運(yùn)算放大器的原理和應(yīng)用1 運(yùn)算放大器的原理 運(yùn)算放大器是目前應(yīng)用最廣泛的一種器件，雖然各中不同的運(yùn)放結(jié)構(gòu)不同，但對(duì)于外部電路而言，其特性

37、都是一樣的。運(yùn)算放大器一般由4個(gè)部分組成，偏置電路，輸入級(jí)，中間級(jí)，輸出級(jí)，其中輸入級(jí)一般是采用差動(dòng)放大電路（抑制電源），中間級(jí)一般采用有源負(fù)載的共射負(fù)載電路（提高放大倍數(shù)），輸出級(jí)一般采用互補(bǔ)對(duì)稱輸出級(jí)電路（提高電路驅(qū)動(dòng)負(fù)載的能力），這里只是簡(jiǎn)單的介紹一下，具體的實(shí)現(xiàn)比較復(fù)雜。工業(yè)上，用來(lái)衡量一個(gè)運(yùn)算放大器的性能的指標(biāo)有很多，一般認(rèn)為實(shí)際運(yùn)算放大器越接近理想運(yùn)放就越好，課堂上我們涉及到的只是要求輸入端等效電阻無(wú)窮大，開環(huán)增益無(wú)窮大，其實(shí)還有很多其他的指標(biāo)，我就簡(jiǎn)要介紹下吧，運(yùn)算放大器的性能指標(biāo)包括5個(gè)，開環(huán)差模電壓放大倍數(shù)，最大輸出電壓，差模輸入電阻，輸出電阻，共模抑制比CMRR。（開環(huán)差模

38、放大倍數(shù)是指集成運(yùn)放在無(wú)外加反饋回路的情況下的差模電壓的放大倍數(shù)。最大輸出電壓是指它是指一定電壓下，集成運(yùn)放的最大不失真輸出電壓的峰-峰值。差模輸入電阻的大小反映了集成運(yùn)放輸入端向差模輸入信號(hào)源索取電流的大小。要求它愈大愈好。輸出電阻的大小反映了集成運(yùn)放在小信號(hào)輸出時(shí)的負(fù)載能力。共模抑制比放映了集成運(yùn)放對(duì)共模輸入信號(hào)的抑制能力，其定義同差動(dòng)放大電路。CMRR越大越好。） 圖1是運(yùn)算放大器的特性曲線，一般用到的只是曲線中的線性部分。如圖2所示。U-對(duì)應(yīng)的端子為“-”，當(dāng)輸入U(xiǎn)-單獨(dú)加于該端子時(shí)，輸出電壓與輸入電壓U-反相，故稱它為反相輸入端。U+對(duì)應(yīng)的端子為“”，當(dāng)輸入U(xiǎn)+單獨(dú)由該端加入時(shí)，輸出

39、電壓與U+同相，故稱它為同相輸入端。輸出：U0= A(U+-U-) ； A稱為運(yùn)算放大器的開環(huán)增益（開環(huán)電壓放大倍數(shù)） 在實(shí)際運(yùn)用經(jīng)常將運(yùn)放理想化，這是由于一般說(shuō)來(lái)，運(yùn)放的輸入電阻很大，開環(huán)增益也很大，輸出電阻很小，可以將之視為理想化的，這樣就能得到：Ri，Ro0，A。由 A,得到U+U-，于是兩個(gè)輸入端可以近似看作短路（稱為“虛短”），如果同向輸入端接地，反向輸入端與地幾乎同電位（稱為“虛地”）。由Ri可知，輸入端電路近似等于0，故可把輸入端看作是斷路（稱之為“虛斷”）。2 運(yùn)算放大器的應(yīng)用 這里只談理想運(yùn)放的應(yīng)用，實(shí)際運(yùn)放可以近似看作是理想運(yùn)放。運(yùn)算放大器的應(yīng)用很廣泛，這里我們只談?wù)動(dòng)蛇\(yùn)算

40、放大器加上其他一些集中性元件組成的運(yùn)算電路。運(yùn)算電路的應(yīng)用相對(duì)其他而言更加廣泛，而且理解起來(lái)方便一些。運(yùn)算電路包括比例電路，和差電路，積分微分電路，對(duì)數(shù)和指數(shù)運(yùn)算電路。1比例電路： 所謂的比例電路就是將輸入信號(hào)按比例放大的電路，比例電路又分為反向比例電路、同相比例電路、差動(dòng)比例電路。（1） 反向比例電路： 反向比例電路如圖3所示，輸入信號(hào)加入反相輸入端，有=0 =0由基爾霍夫定律知：= 即（-）/=（-）/得： =由此知道，輸出電壓U0與輸入電壓Ui稱比例關(guān)系，方向相反，改變比例系數(shù)，即改變兩個(gè)電阻的阻值就可以改變輸出電壓的值。反向比例電路對(duì)于運(yùn)放的性能也有一定的性能要求，比如對(duì)輸入信號(hào)的負(fù)載

41、能力有一定的要求.。（2） 同向比例電路（圖4）： 跟反向比例電路本質(zhì)上差不多，除了同向接地的一段是反向輸入端，由= =得：/=(-)/即 =于是只要改變比例系數(shù)就能改變輸出電壓，且Ui與U0的方向相同，當(dāng)然同向比例電路也是有一定要求的，比如對(duì)集成運(yùn)放的共模抑制比要求高. （3） 差動(dòng)比例電路（圖5）： =輸入信號(hào)分別加在反相輸入端和同相輸入端，具體的步驟和前兩個(gè)差不多就不在推導(dǎo)了，最后得到： 由此我們可以看出它實(shí)際完成的是：對(duì)輸入兩信號(hào)的差運(yùn)算。 2和差電路： 和差電路也是一種運(yùn)用比較廣泛的電路，這里就舉三個(gè)電路：反向求和電路，同向求和電路，和差電路。（1） 反向求和電路與同向求和電路： 兩者差別只在于輸入信號(hào)加入了反相輸入端與同相輸入端的差別，反向求和電路如圖6，同向求和電路如圖7。由基爾霍夫電流定律，反向求和電路的輸