電氣類畢業(yè)設(shè)計(jì)外文翻譯3

1、<p><b>　　附錄1 譯文</b></p><p>　　A/D 轉(zhuǎn)換器按照轉(zhuǎn)換原理可分為直接A/D 轉(zhuǎn)換器和間接A/D 轉(zhuǎn)換器。所謂直接A/D 轉(zhuǎn)換器，是把 模擬信號(hào)直接轉(zhuǎn)換成數(shù)字信號(hào)，如逐次逼近型，并聯(lián)比較型等。其中逐次逼近型A/D 轉(zhuǎn)換器，易于用集成工藝實(shí)現(xiàn)，且能達(dá)到較高的分辨率和速度，故目前集成化A/D 芯片采用逐次逼近型者多；間接A/D 轉(zhuǎn)換器是先把模擬量轉(zhuǎn)換成中間量

2、，然后再轉(zhuǎn)換成數(shù)字量，如電壓/時(shí)間轉(zhuǎn)換型（積分型），電壓/頻率轉(zhuǎn)換型，電壓/脈寬轉(zhuǎn)換型等。 其中積分型A/D 轉(zhuǎn)換器電路簡(jiǎn)單，抗干擾能力強(qiáng)，切能作到高分辨率，但轉(zhuǎn)換速度較慢。 有些轉(zhuǎn)換器還將多路開關(guān)、基準(zhǔn)電壓源、時(shí)鐘電路、譯碼器和轉(zhuǎn)換電路集成在一個(gè)芯片內(nèi)，已超出了單純A/D 轉(zhuǎn)換功能，使用十分方便。</p><p>　　ADC 經(jīng)常用于通訊、數(shù)字相機(jī)、儀器和測(cè)量以及計(jì)算機(jī)系統(tǒng)中，可方便數(shù)字訊號(hào)處理和信息的儲(chǔ)存。大

3、多數(shù)情況下，ADC 的功能會(huì)與數(shù)字電路整合在同一芯片上，但部份設(shè)備仍需使用獨(dú)立的ADC。行動(dòng)電話是數(shù)字芯片中整合ADC 功能的例子，而具有更高要求的蜂巢式基地臺(tái)則需依賴獨(dú)立的ADC 以提供最佳性能。</p><p>　　ICL7107是三位半雙積分型A/D轉(zhuǎn)換器，屬于CMOS大規(guī)模集成電路，它的最大顯示值為士1999，最小分辨率為100μV。能直接驅(qū)動(dòng)共陽(yáng)極LED數(shù)碼管，不需要另加驅(qū)動(dòng)器件，采用士5V兩組電源供電

4、，在芯片內(nèi)部從與COM之間有一個(gè)穩(wěn)定性很高的2.8V基準(zhǔn)電源，通過電阻分壓器可獲得所需的基準(zhǔn)電壓。能通過內(nèi)部的模擬開關(guān)實(shí)現(xiàn)自動(dòng)調(diào)零和自動(dòng)極性顯示功能，輸入阻抗高，對(duì)輸入信號(hào)無衰減作用。整機(jī)組裝方便，無需外加有源器件，配上電阻、電容和LED共陽(yáng)極數(shù)碼管，就能構(gòu)成一只直流數(shù)字電壓表頭。噪音低，溫漂小，具有良好的可靠性，壽命長(zhǎng)。芯片本身功耗小于15mv(不包括LED)，不設(shè)有專門的小數(shù)點(diǎn)驅(qū)動(dòng)信號(hào)。使用時(shí)可將LED共陽(yáng)極數(shù)數(shù)碼管公共陽(yáng)極接，可以

5、方便的進(jìn)行功能檢查。</p><p>　　雙積分型A/D轉(zhuǎn)換器內(nèi)部包括積分器、比較器、計(jì)數(shù)器，控制邏輯和時(shí)鐘信號(hào)源。積分器是A/D轉(zhuǎn)換器的心臟，在一個(gè)測(cè)量周期內(nèi)，積分器先后對(duì)輸入信號(hào)電壓和基準(zhǔn)電壓進(jìn)行兩次積分。比較器將積分器的輸出信號(hào)與零電平進(jìn)行比較，比較的結(jié)果作為數(shù)字電路的控制信號(hào)。時(shí)鐘信號(hào)計(jì)數(shù)器對(duì)反向積分過程的時(shí)鐘脈沖進(jìn)行計(jì)數(shù)?？刂七壿嫲ǚ诸l器、譯碼器、相位驅(qū)動(dòng)器、控制器和鎖存器。分頻器用來對(duì)時(shí)鐘脈沖逐漸分

6、頻，得到所需的計(jì)數(shù)脈沖和共陽(yáng)極LED數(shù)碼管公共電極所需的方波信號(hào)。譯碼器為BCD七段譯碼器，將計(jì)數(shù)器的BCD碼譯成LED數(shù)碼管七段筆畫組成數(shù)字的相應(yīng)編碼。驅(qū)動(dòng)器是將譯碼器輸出對(duì)應(yīng)于共陽(yáng)極數(shù)碼管七段筆畫的邏輯電平變成驅(qū)動(dòng)相應(yīng)筆畫的方波。控制器的作用有三個(gè)：第一，識(shí)別積分器的工作狀態(tài)，適時(shí)發(fā)出控制信號(hào)，使各模擬開關(guān)接通或斷開，A/D轉(zhuǎn)換器能循環(huán)進(jìn)行。第二，識(shí)別輸入電壓極性，控制LED數(shù)碼管的負(fù)號(hào)顯示。第二，當(dāng)輸入電壓超量限時(shí)發(fā)出溢出信號(hào)，使

7、符號(hào)位顯示“1”，其余碼全部熄滅。調(diào)鎖存器用來存放A/D轉(zhuǎn)換的結(jié)果，鎖存器的輸出經(jīng)譯碼器后驅(qū)動(dòng)LED 。</p><p>　　雙積分模數(shù)轉(zhuǎn)換器ICL7107的工作原理：當(dāng)輸入電壓一定時(shí)，在一定時(shí)間內(nèi)對(duì)電量為零的電容器進(jìn)行恒流（電流大小與待測(cè)電壓成正比）充電，這樣電容器兩極之間的電量將隨時(shí)間線性增加，當(dāng)充電到一定時(shí)間后，電容器上積累的電量與被測(cè)電壓成正比。然后讓電容器恒流放電（電流大小與參考電壓成正比），這樣電容器

8、兩極之間的電量將線性減小，直到T2時(shí)刻減小為零。所以，可以得出T2也與Vx成正比。如果用計(jì)數(shù)器在T2開始時(shí)刻對(duì)時(shí)鐘脈沖進(jìn)行計(jì)數(shù)，結(jié)束時(shí)刻停止計(jì)數(shù)，得到計(jì)數(shù)值N2，則N2與Vx成正比。雙積分式AD轉(zhuǎn)換器的工作原理就是基于上述電容器充放電過程中計(jì)數(shù)器讀數(shù)N2與輸入電壓Vx成正比構(gòu)成的。</p><p>　　ICL7107雙積分式A/D轉(zhuǎn)換器的基本組成如圖1-1所示。</p><p>　　圖1-

9、1 ICL7107內(nèi)部結(jié)構(gòu)圖</p><p>　　ICL7107內(nèi)部由積分器、過零比較器、邏輯控制電路、閘門電路、計(jì)數(shù)器、時(shí)鐘脈沖源、鎖存器、譯碼器及顯示等電路所組成。它的轉(zhuǎn)換電路大致分為三個(gè)階段：</p><p>　　第一階段，首先電壓輸入腳與輸入電壓斷開而與地端相連放掉電容器C上積累的電量，然后參考電容充電到參考電壓值，同時(shí)反饋環(huán)給自動(dòng)調(diào)零電容CAZ以補(bǔ)償緩沖放大器、積分器和比較器的偏

10、置電壓。這個(gè)階段稱為自動(dòng)校零階段。</p><p>　　第二階段為信號(hào)積分階段（采樣階段），在此階段Vs接到Vx上使之與積分器相連，這樣電容器C將被以恒定電流充電，與此同時(shí)計(jì)數(shù)器開始計(jì)數(shù)，對(duì)于三位半模數(shù)轉(zhuǎn)換器，當(dāng)計(jì)到某一特定值（N1=1000）時(shí)充電過程結(jié)束，這樣采樣時(shí)間T1是恒定的，假設(shè)時(shí)鐘脈沖為TCP，則T1的計(jì)算見公式（1-1）：</p><p>　　T1=N1×TCP

11、 （1-1）</p><p>　　在此階段，Vo與Vx極性相反，Qo為T1時(shí)間內(nèi)恒流給電容器C充電得到的電量，Qo和Vo的計(jì)算見公式（1-1）和（1-2）：</p><p>　　Qo == （1-2）</p><p>　　Vo = -= -

12、 （1-3）</p><p>　　第三階段為反積分階段（測(cè)量階段），在此階段，邏輯控制電路把已經(jīng)充電至的參考電容按與極性相反的方式經(jīng)緩沖器接到積分電路，這樣電容C將以恒定的電流放電，與此同時(shí)計(jì)數(shù)器開始計(jì)數(shù)，電容器C上的電量線性減小，當(dāng)經(jīng)過時(shí)間T2后，電容器電壓減小到0，由零值比較器輸出閘門控制信號(hào)再停止計(jì)數(shù)器計(jì)數(shù)并顯示出計(jì)數(shù)結(jié)果。此階段關(guān)系見公式（1-4）：</p&

13、gt;<p>　　Vo+=0 （1-4）</p><p>　　把式（1-3）代入式（1-4）,所得結(jié)果見式（1-5）：</p><p>　　T2=×Vx （1-5） 從式（1-5）可以看出，由于T1和均為常數(shù)，

14、所以T2與Vx成正比，從圖1-1可以看出。若時(shí)鐘最小脈沖單元為,則T1和T2的計(jì)算見公式（1-6）和（1-7）：</p><p><b>　　（1-6）</b></p><p><b>　?。?-7）</b></p><p>　　代入式（1-5），即有式（1-8）：</p><p>　　N2=

15、15;Vx （1-8）</p><p>　　可以得出測(cè)量的計(jì)數(shù)值N2與被測(cè)電壓Vx成正比。</p><p>　　雙積分型A/D轉(zhuǎn)換器ICL7107是一種間接A/D轉(zhuǎn)換器。它通過對(duì)輸入模擬電壓和參考電壓分別進(jìn)行兩次積分，將輸入電壓平均值變換成與之成正比的時(shí)間間隔，然后利用脈沖時(shí)間間隔，進(jìn)而得出相應(yīng)的數(shù)字性輸出。對(duì)于ICL7107，信號(hào)積分階

16、段時(shí)間固定為1000個(gè),即N1的值為1000不變。而N2的計(jì)數(shù)隨Vx的變化范圍為0～1999，同時(shí)自動(dòng)校零的計(jì)數(shù)范圍為2999～1000，也就是測(cè)量周期總保持在4000個(gè)不變。即滿量程時(shí)N2最大值見式（1-9）：</p><p>　　= 2×N1= 2000 （1-9）</p><p>　　Vx最大值見式（1-10）：</p>&l

17、t;p>　　= 2× （1-10）</p><p>　　這樣若取參考電壓為100mV，則最大輸入電壓為200mV；若參考電壓為1V，則最大輸入電壓為2V。</p><p>　　圖1-2 ICL7107內(nèi)部電壓變化圖</p><p>　　附錄2 英文參考資料</p><p>　　A / D c

18、onverter can be divided in accordance with the principle of direct conversion A / D converter and indirect A / D converter. The so-called direct A / D converter, is to directly convert analog signals into digital signals

19、, such as successive approximation, parallel comparison type. Which successive approximation A / D converter, easy to use integrated process to achieve and can achieve higher resolution and speed, so the current integrat

20、ed A / D chip successive approximation are many; indi</p><p>　　ADC often used for communications, digital cameras, equipment and measurement and computer systems, digital signal processing can be easily and

21、information storage. In most cases, ADC will feature integration with digital circuits on the same chip, but part of the equipment needed to use a separate ADC. Mobile phone is a digital chip integrated ADC features exam

22、ples and a more demanding cellular base station independent of the ADC need to rely on to provide the best performance.</p><p>　　ICL7107 is one of three semi-double integral type A / D converter, are CMOS LS

23、I, the largest show of its 1999 value of persons, the minimum resolution of 100μV. Can directly drive common anode LED digital tube, the device does not require additional drivers, two 5V power supply with disabilities,

24、and the COM in the chip from a high stability between the 2.8V reference supply through a resistor divider obtain the necessary reference voltage. Through the analog switch inside the automatic zero adj</p><p&

25、gt;　　Double integral type A / D converter includes an internal integrator, comparator, counter, control logic and clock signal source. Integrator is the A / D converter in the heart of a measurement cycle, the integrator

26、 has the input signal voltage and reference voltage for two points. Comparator to the integrator output signal compared with the zero level to compare the results of the control signal as a digital circuit. Clock signal

27、on the reverse integration process of counter clock pulse count. </p><p>　　Double integral ADC ICL7107 works: When the input voltage is constant, within a certain time, the capacitor charge is zero constant

28、current (current and sensed voltage is proportional to the size of) charge, so that the capacitor between the power poles will be increases linearly with time, when the charge to a certain time, the accumulation of charg

29、e on the capacitor and the measured voltage. Then let the capacitor discharge current (current is proportional to the size of the reference voltage)</p><p>　　ICL7107 internally by the integrator, zero crossi

30、ng comparator, logic control circuits, gate circuits, counters, clock source, latch, decoder and display circuit. Its conversion circuit can be divided into three stages:</p><p>　　The first stage, the first

31、voltage input pin and disconnect the input voltage is connected with the land-side let go of the power accumulated in capacitor C, and then refer to the reference voltage capacitor charging, while the feedback loop to th

32、e auto-zero capacitor CAZ to compensate for the buffer amplifier, Integrator and comparator offset voltage. This phase is called auto-zero phase.</p><p>　　The second stage is the signal integration phase (sa

33、mpling phase), at this stage on the Vs Vx received so connected with the integrator, so that the capacitor C is a constant current charge, while the counter starts counting module for the three and a half Converter to a

34、specific value when the count (N1 = 1000) when the charging process is complete, so that T1 is a constant sampling time, assuming the clock pulse as TCP, then see the formula for the calculation of T1 （1-1）:</p>&

35、lt;p>　　T1=N1×TCP （1-1）</p><p>　　At this stage, Vo and Vx opposite polarity, Qo for the T1 time constant for charging the capacitor C are the power, Qo and Vo calc

36、ulation see formula （1-1） and （1-2）:</p><p>　　Qo == （1-2）</p><p>　　Vo = -= - （1-3）</p><p>　　The third phase of the anti-integration

37、 phase (measuring time), at this stage, the logic control circuit to the reference capacitor has been charged to opposite polarity by the way and the buffer received by the integrator, so that a constant current of capac

38、itor C will discharge At the same time counter starts counting the charge on the capacitor C decreases linearly, when the elapsed time T2, the capacitor voltage is reduced to 0, the zero value of the comparator output ga

39、te control signal and</p><p>　　Vo+=0 （1-4）</p><p>　　Skill (1-3) into (1-4), the results see the formula (1-5):</p><p>　　T2=×Vx （1

40、-5） </p><p>　　From (1-5) can be seen, the T1 and are constants, so the T2 and Vx is proportional, can be seen from Figure 1-1. If the clock pulse unit is the smallest, then the calculation of T1 and T2,

41、see equation (1-6) and (1-7):</p><p><b>　?。?-6）</b></p><p><b>　?。?-7）</b></p><p>　　Into (1-5), that is, equation (1-8):</p><p>　　N2=×Vx

42、 （1-8）</p><p>　　Count measure can be drawn with the measured voltage Vx is proportional to N2.</p><p>　　Double integral type A / D converter is an indirect ICL7107 A / D co

43、nverter. It is through the input analog voltage and reference voltage for two points, respectively, will be converted into associated input voltage proportional to the average time interval, and pulse interval, and then

44、draw the corresponding number of outputs. For the ICL7107, the signal integration period of time is fixed at 1000, that is, the same N1 value is 1000. The count of N2 change with the Vx range of 0 to 1999, while </p&g

45、t;<p>　　= 2×N1= 2000 （1-9）</p><p>　　Vx max see Eq (1-10):</p><p>　　= 2× （1-10）</p><p>　　So if we take the reference voltage is