外文翻譯--運算放大器的原理和應用

1、<p>　　Operational amplifier theory and applications</p><p>　　1 the principle of op-amp Op amp is the most widely used of a device, although the different structure of different operational amplifier, b

2、ut the external circuit, its characteristics are the same. Op amp is usually 4 parts, bias circuits, input stage, intermediate-level, output level, which is generally used input stage differential amplifier circuit (inhi

3、bitory power), the middle class in general the use of active load circuit loads the total radio (increase the magnification), the complemen</p><p>　　Figure 1 op-amp characteristic curve</p><p>　

4、　Figure 2 op-amp input and output terminal map</p><p>　　Figure 1 is the characteristic curve of amplifier is generally used only the linear part of curve. As shown in Figure 2. U-corresponding to the termina

5、l "-", 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 f

6、rom the client to join, the output voltage and U + with the phase, so called in-phase input. Output: U0 = A (U +-U-); A known as the op amp's open l</p><p>　　2 Application of Operational Amplifiers Her

7、e only the application of the ideal operational amplifier, the actual op amp can be seen as similar to an ideal operational amplifier. Application of operational amplifiers is very broad, here we only talk about the op-a

8、mp 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

9、including the ci</p><p>　　Figure 3 the ratio of the reverse circuit schematics</p><p>　　Figure 4 with the ratio of circuit schematics</p><p>　　==0 ==0</p><p>　　Know

10、 from Kirchhoff's law:</p><p>　　= （-）/=（-）/</p><p><b>　　=</b></p><p>　　Thus know that the output voltage U0 and the ratio of input voltage Ui said the relationship b

11、etween the opposite direction, changing the ratio of coefficients, namely, two resistors of resistance to change can change the value of output voltage. Reverse the ratio of operational amplifier circuits for the perform

12、ance of a certain performance requirements, such as the input signal to a certain load capacity requirements..</p><p>　　(2) the ratio of the circuit in the same direction (Figure 4): With the reverse ratio

13、of the circuit is essentially similar, apart from a section of ground in the same direction is the reverse input from</p><p>　　== =得：/=(-)/</p><p><b>　　SO: =</b></p><p&g

14、t;　　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 circuit is to have a certain requirements, such

15、as the integrated operational amplifier of the common mode rejection ratio requirements. (3) the ratio of differential circuit (Figure 5):</p><p><b>　　=</b></p><p>　　Input signal, r

16、espectively, added to the RP-phase input and input, the specific steps and not in the first two are derived almost And in the end be: From this we can see that it is actually completed: two of the input differential si

17、gnal 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 the same circuit, and differenti

18、al circuits. (1) reverse summation circuit a</p><p><b>　　=</b></p><p>　　Figure 5 the proportion of the circuit differential circuit</p><p>　　Figure 6 Reverse summation

19、circuit schematics</p><p>　　Figure 7 with the circuit diagrams and circuit</p><p>　　With the summation circuit output voltage and the relationship between the input voltage as follows:</p>

20、<p><b>　　=</b></p><p>　　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

21、 convenient for the input resistance of a circuit to change the relationship between the proportion of the circuit without affecting the relationship between the proportion of other routes. And with the application to th

22、e summation circuit is not very extensive, mainly because of its better regulation of RP-sum circuit, and its large </p><p>　　Its circuit diagram is shown in Figure 8. The function of this circuit is Ui1, Ui

23、2 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:</p><p><b>

24、;　　=</b></p><p>　　Figure 8 and the differential circuit schematics</p><p>　　As the use of an integrated circuit operational amplifier, and its calculation and the circuit resistance is not

25、 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, it's the relationship between input and output voltage is:<

26、/p><p><b>　　=</b></p><p>　　Figure 9 composed of two integrated operational amplifier circuit schematics and poor</p><p>　　Its former level after the level does not affect (

27、in the ideal of integrated operational amplifier), which is very convenient calculation. 3. Integral and differential circuit: The above components used are basically resistive element, if one side of the resistor capa

28、citor 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 computing, such as triangula

29、r waveform</p><p><b>　　=</b></p><p>　　One: that the initial capacitor voltage at both ends. If the circuit input voltage waveform is a square, then have a triangular waveform output.

30、 (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 output voltage

31、and input voltage relations showed differential. Circuit diagram shown in Figure 11: its input and output voltage relationship:</p><p><b>　　=</b></p><p>　　Circuit schematics Figure 1

32、0 point</p><p>　　Figure 11 Differential circuit schematics</p><p>　　4. And the index calculation on the number of circuits: Circuit used for a number of diodes, diode characteristics of the mos

33、t 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 n

34、umber of operation circuits:</p><p><b>　　=</b></p><p>　　Logarithm computing circuit output voltage and input voltage was logarithmic function. RP we use the ratio of Rf diode circuit

35、 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 is</p><p>　　Figure 12 Logarithm computing circu

36、it schematics</p><p>　　Figure 13 Index computation circuit schematics</p><p>　　In fact, transistor can also be used in place of diodes, the principle is the same, in addition to a multi-line con

37、nections. (2) index operation circuits:</p><p><b>　　=</b></p><p>　　Index calculation on the number of circuits and circuit computing the difference is only diodes and resistors to e

38、ach 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

39、Its input and output voltage relationship</p><p>　　Use of computing as well as index number and the proportion of poor operation and circuit can be composed of multiplication or division operation circuits a

40、nd other non-linear operation circuit, will no longer be described here.</p><p><b>　　中文翻譯：</b></p><p>　　運算放大器的原理和應用</p><p>　　1 運算放大器的原理 </p><p>　　運算放大器是目前應用

41、最廣泛的一種器件，雖然各中不同的運放結構不同，但對于外部電路而言，其特性都是一樣的。運算放大器一般由4個部分組成，偏置電路，輸入級，中間級，輸出級，其中輸入級一般是采用差動放大電路（抑制電源），中間級一般采用有源負載的共射負載電路（提高放大倍數(shù)），輸出級一般采用互補對稱輸出級電路（提高電路驅動負載的能力），這里只是簡單的介紹一下，具體的實現(xiàn)比較復雜。</p><p>　　工業(yè)上，用來衡量一個運算放大器的性能的指標

42、有很多，一般認為實際運算放大器越接近理想運放就越好，課堂上我們涉及到的只是要求輸入端等效電阻無窮大，開環(huán)增益無窮大，其實還有很多其他的指標，我就簡要介紹下吧，運算放大器的性能指標包括5個，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)差模放大倍數(shù)是指集成運放在無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

43、映了集成運放輸入端向差模輸入信號源索取電流的大小。要求它愈大愈好。輸出電阻的大小反映了集成運放在小信號輸出時的負載能力。共模抑制比放映了集成運放對共模輸入信號的抑制能力，其定義同差動放大電路。CMRR越大越好。） </p><p>　　圖1是運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-對應的端子為“-”，當輸入U-單獨加于該端子時，輸出電壓與輸入電壓U-反相，故稱它為反相輸入端。U+對應

44、的端子為“＋”，當輸入U+單獨由該端加入時，輸出電壓與U+同相，故稱它為同相輸入端。</p><p>　　輸出：U0= A(U+-U-) ； A稱為運算放大器的開環(huán)增益（開環(huán)電壓放大倍數(shù)） </p><p>　　在實際運用經(jīng)常將運放理想化，這是由于一般說來，運放的輸入電阻很大，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≈∞，Ro≈0，A≈∞。由 A≈∞,得到U+

45、≈U-，于是兩個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”）。</p><p>　　2 運算放大器的應用 </p><p>　　這里只談理想運放的應用，實際運放可以近似看作是理想運放。運算放大器的應用很廣泛，這里我們只談談由運算放大器加上其他一些集中性元件

46、組成的運算電路。運算電路的應用相對其他而言更加廣泛，而且理解起來方便一些。運算電路包括比例電路，和差電路，積分微分電路，對數(shù)和指數(shù)運算電路。</p><p><b>　　1．比例電路： </b></p><p>　　所謂的比例電路就是將輸入信號按比例放大的電路，比例電路又分為反向比例電路、同相比例電路、差動比例電路。</p><p>　?。?）

47、 反向比例電路： </p><p>　　反向比例電路如圖3所示，輸入信號加入反相輸入端，有</p><p>　　==0 ==0</p><p><b>　　由基爾霍夫定律知：</b></p><p>　　= 即（-）/=（-）/</p><p>　　得：

48、 =</p><p>　　由此知道，輸出電壓U0與輸入電壓Ui稱比例關系，方向相反，改變比例系數(shù)，即改變兩個電阻的阻值就可以改變輸出電壓的值。反向比例電路對于運放的性能也有一定的性能要求，比如對輸入信號的負載能力有一定的要求.。</p><p>　?。?） 同向比例電路（圖4）： </p><p>　　跟反向比例電路本質上差不多，除了同向接地的一段是反向輸入端，由

49、</p><p>　　== =得：/=(-)/</p><p><b>　　即 </b></p><p><b>　　=</b></p><p>　　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，當然同向比例電路也是有一定要求的，比如對集成運放的共模抑制比要求高. </p

50、><p>　　（3） 差動比例電路（圖5）： </p><p><b>　　=</b></p><p>　　輸入信號分別加在反相輸入端和同相輸入端，具體的步驟和前兩個差不多就不在推導</p><p><b>　　了，最后得到： </b></p><p>　　由此我們可以看出它實際

51、完成的是：對輸入兩信號的差運算。 </p><p><b>　　2．和差電路： </b></p><p>　　和差電路也是一種運用比較廣泛的電路，這里就舉三個電路：反向求和電路，同向求和電路，和差電路。</p><p>　　（1） 反向求和電路與同向求和電路： </p><p>　　兩者差別只在于輸入信號加入了反相輸入端

52、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，反向求和電路的輸出電壓和輸入電壓的關系為: </p><p><b>　　=</b></p><p>　　圖5 差動比例電路電路圖 圖6 反向求和電路電路圖</p><p>　　同向求和電路的輸出電壓和輸入電

53、壓的關系為：</p><p><b>　　=</b></p><p>　　雖然兩者比較類似，但還是有區(qū)別的，反向求和電路的特點與反相比例電路相同。它可十分方便的某一電路的輸入電阻，來改變電路的比例關系，而不影響其它路的比例關系。而同向求和電路的應用不是很廣泛，主要由于它的調節(jié)不如反相求和電路，而且它的共模輸入信號大。</p><p>　?。?）

54、 和差電路： </p><p>　　它的電路圖如圖8所示。此電路的功能是對Ui1、Ui2進行反相求和，對Ui3、Ui4進行同相求和，然后進行的疊加即得和差結果，他的輸入輸出電壓關系為：</p><p><b>　　=</b></p><p>　　圖8 和差電路電路圖</p><p>　　由于該電路用一只集成運放，它的電阻

55、計算和電路調整均不方便，因此我們常用二級集成運放組成和差電路。它的電路圖如圖9所示，它的輸入輸出電壓的關系是：</p><p><b>　　=</b></p><p>　　它的后級對前級沒有影響（采用的是理想的集成運放），它的計算十分方便。</p><p>　　3．積分和微分電路： </p><p>　　以上用到的元件基

56、本上都是電阻元件，如果其中端的電阻換成電容，那么結果就會變成積分電路和微分電路。 </p><p>　?。?） 積分電路： </p><p>　　如圖10所示的電路，它可實現(xiàn)積分運算及產(chǎn)生三角波形等。積分運算是：輸出電壓與輸入電壓呈積分關系。它是利用電容的充放電來實現(xiàn)積分運算，它的輸入、輸出電壓的關系為：</p><p><b>　　=</b>

57、</p><p>　　其中:表示電容兩端的初始電壓值。如果電路輸入的電壓波形是方形，則產(chǎn)生三角波形輸出。</p><p>　?。?） 微分電路： </p><p>　　微分電路與積分電路的區(qū)別只是電阻和電容位置互換。微分是積分的逆運算，它的輸出電壓與輸入電壓呈微分關系。電路圖如圖11所示：它的輸入、輸出電壓的關系為：</p><p><

58、b>　　=</b></p><p>　　4．對數(shù)和指數(shù)運算電路： </p><p>　　對數(shù)電路使用了二極管，二極管最重要的特性就是單方向導電性。在電路中，電流只能從二極管的正極流入，負極流出，正是利用這個特性而實現(xiàn)了對數(shù)和指數(shù)電路。</p><p>　?。?） 對數(shù)運算電路： </p><p><b>　　=&l

59、t;/b></p><p>　　對數(shù)運算電路輸出電壓與輸入電壓呈對數(shù)函數(shù)。我們把反相比例電路中Rf用二極管代替即組成了對數(shù)運算電路。電路圖如圖12所示。于是他的輸出輸入電壓關系是</p><p>　　其實也可以用三極管代替二極管，原理是一樣的，除了要多連接一條線路。 </p><p>　?。?） 指數(shù)運算電路： </p><p><

60、;b>　　=</b></p><p>　　指數(shù)運算電路與對數(shù)運算電路差別僅僅只是把二極管和電阻互相位置，指數(shù)運算電路是對數(shù)運算的逆運算,將指數(shù)運算電路的二極管(三級管)與電阻R對換即可。電路圖如13所示</p><p>　　它的輸入、輸出電壓的關系為</p><p>　　利用對數(shù)和指數(shù)運算以及比例，和差運算電路，可組成乘法或除法運算電路和其它非線性