主題儀表放大器--常見的應(yīng)用問題和解決方案

1、主題：儀表放大器-常見的應(yīng)用問題和解決方案問答集錦：?jiǎn)枺簔w-wu我現(xiàn)在用了AD620與AD8221儀表放大器,但在使用過程中,有時(shí)輸出會(huì)出現(xiàn)一些干擾信號(hào),不知這些儀表放大器怎樣才能減小無(wú)用信號(hào),提高共模抑制 答：Forest你可以在輸入端之前加入低通濾波器，就可以減少干擾信號(hào)了。今天的資料中就有詳細(xì)的介紹。 問：zhangxk在應(yīng)變片式傳感器（Load cell）的放大、轉(zhuǎn)換電路中，要將A/D分辨率提高到19位以上，并且轉(zhuǎn)換速度大于50sps，應(yīng)選用什幺樣的芯片組合，或者電路設(shè)計(jì)中應(yīng)該考慮哪些因素？ 答：Jingyou should pay attentatio

2、n to the throughput that will be trade off with your accuracy.You should also pay attentation to your input range and offset I think you can refer to our AD7730L or AD7799 .If you just want to use AMP+ADC , you can consider AD8230.It"s a chopper-stable instrument amplifier. 問：xianluc如何將設(shè)計(jì)A

3、D623的輸入電路，使AD623單電源+5V供電時(shí)，輸出信號(hào)為0+5V？ 答：MariahIn single supply condition, the input common mode voltage is very critical to get the rail to rail output. One good tool to analyze the circuit of AD623 in single supply condition can be got from the link below:問：zzb6503在設(shè)計(jì)電路時(shí)，怎樣盡可能使儀表放大器抑制50Hz市電干擾？&

4、#160;答：ForestAD8221儀表放大器放大器本身就具有很強(qiáng)的共模抑制比，他可以在一定程度上抑制市電的干擾。另外，我們建議在你后續(xù)的模擬和數(shù)字電路加入帶阻濾波器。 問：zcw0707在測(cè)量微小電流時(shí)，需要串入隔離放大器，怎幺減小隔離放大器帶來(lái)的影響？ 答：Yiming如果一定要采用隔離放大器，那幺隔離放大器的性能不應(yīng)該惡化輸入信號(hào)，也就是選用低噪聲的隔離放大器。 問：zhangxk如何實(shí)現(xiàn)應(yīng)變片式傳感器（Load cell）的交流激勵(lì)、放大及轉(zhuǎn)換？ 答：JingYou can use ratiomeric method and AC extinc

5、tion.AC Excitation can be used to cancel out offset errors, regardless of their source.  AC Excitation here means that 2 sets of readings are taken, with the excitation voltage to the bridge reversed.  Subtracting the 2 readings cancels out the offset errors, as shown in the boxe

6、d equation.  This technique requires that the readings be stored and subtracted.  This is an effective technique, but if you implemented this with discrete components you would add more error than you were subtracting. 問：metrolog現(xiàn)在設(shè)計(jì)的儀表放大器失調(diào)電壓的溫度系數(shù)可達(dá)到10nV/K嗎？ 答：SteveThe

7、 lowest drift instrumentation amplifier we have is the AD8230 which has 50nV/C. The AD8555 has 65nV/C and the AD8553 has 100nV/C. We do not have any instrumentation amplifier that has 10nV/C of drift at this time 問：mxslgyb請(qǐng)介紹一下儀表放大器和通用放大器的區(qū)別，謝謝！ 答：Forest通常儀表放大器是由三個(gè)運(yùn)放和一些集成的電阻組成，它具有較高的輸入電阻，很

8、高的共模抑制比，通常用在信號(hào)的最前端進(jìn)行信號(hào)處理。如果用通用放大器組成儀表放大器的形式，由于電阻和運(yùn)放的不匹配，性能上會(huì)有很大的損失，尤其是共模抑制比。 問：luoqq模擬數(shù)字地要分割嗎？ 答：MariahIf your circuit is low frequency and need high accuracy, you need to separate the analog ground and digital ground. 問：wangqf2422ADX250芯片用于馬達(dá)、泵、壓縮機(jī)監(jiān)控測(cè)量振動(dòng)指標(biāo)，如何降低電路信號(hào)噪聲？如何降低功耗？ 答：Y

9、iming降低噪聲的方法：1. 用線性電源，2. 在加速度輸出端，用合適的低通濾波器把高頻噪聲濾掉。降低功耗的方法：可以降低電源電壓，但是這樣靈敏度會(huì)下降。 問：wy56請(qǐng)問：我在進(jìn)行儀表電路設(shè)計(jì)時(shí)，想將靜態(tài)工作電壓隔離掉，該如何處理？例如：傳感器輸出的電壓是0.51.8V，我想只取用該段電壓進(jìn)行放大及后續(xù)處理，該如何做？ 答：EagleYou can use AC couple, but you need to resistors to connect to GND to provide DC bias. In this way, the high input imped

10、ence is lower down by this resistors. For example, AD8221 differential input impendence is 100G Ohm, if use 1M Ohm resistors, the input impedence will be less than 1M Ohm. In this case, we can use a JFET input amplifier to buffer the input to get high impendence fist, then use AC couple to IIA such

11、as AD8221. 問：zj2172我公司產(chǎn)品用的傳感器采用橋式電路，輸出的信號(hào)可正可負(fù)，但給儀器放大器提供的電源是5V單電源，目前是給儀器放大器的參考電源端提供了一個(gè)2.5V的偏置電壓，請(qǐng)問這種用法可靠嗎，會(huì)不會(huì)有什幺問題，有沒有更好的解決方法？謝謝！ 答：SteveDo you mean the sensor can swing below GND? If the sensor output is between 0V and 5V then this configuration is OK to amplify the output signal of the se

12、nsor. But you cannot condition a bridge that outputs negative voltages if the instrumentation amplifier is operating on only +5V supplies.問：lijin_as為何儀表放大器不能做到Rail to Rail？ 答：ForestAD623 AD8220是可以做到rail to rail 問：lwtbenbenAs we know,AD603 can work at the frequency of 90MHz.But I want know

13、how can I ruduce the EMI when I design the PCB board?Thank you! 答：SteveYou can use ferrite beads or a common-mode choke at the inputs of the AD603. 問：dxp0715我采集的有用信號(hào)是50Hz,但發(fā)現(xiàn)經(jīng)過運(yùn)放后信號(hào)迭加了一些干擾信號(hào)，我想在A/D前端加一低通濾波電路，請(qǐng)問設(shè)計(jì)這個(gè)電路時(shí)需不需要考慮A/D的采樣頻率 答：Jingyou can add a low pass filter before A/D. But y

14、ou should consider your interested bandwidth and the ADC bandwidth .If you want to get more accuracy,you can slow down the sample rate. 問：zw-wu我想問一下,我要用在電能質(zhì)量監(jiān)測(cè)方面,不知選用什幺儀表放大器比較好一點(diǎn) 答：EagleI am sorry we do not know exactly the requirement. If you need low cost and you can use +/-5V power supp

15、ly, then AD623 is a good choice. 問：paynewon請(qǐng)問如何設(shè)計(jì)差動(dòng)放大器，保證最低的溫飄和噪聲。 答：YimingADI提供集成的difference Amplifier，比如AD82xx系列 問：unaffectedwhy the in-amp constructed by off-chip resistor"s CMRR performance is worse than integrated in-amps? 答：SteveIn-amps need matched resistor ratios for

16、 high CMRR. You can get high performance with external resistors if the resistors are well matched. This can happen if you buy an integrated resistor array. These arrays cost more than the amplifier. So if you want low cost and high performance, you should use a monolithic instrumentation amplifier.

17、 問：kingway98看了關(guān)于AD8221的演講！不知道將他用做儀表前端放大的時(shí)候，特別是接傳感器的時(shí)候，對(duì)于電源有沒有什幺特殊要求！ 答：JingIt"s very hard to summarize it in one sentence . It will depend on your real system requirement.Generally, your power supply should be less ripple voltage and should be larger than what you will in/output and y

18、ou should also reserve enough headroom for your output. if you can use +/- power supply should be better. 問：xsj19810419為提高拾取電路的靈敏度，應(yīng)該采取怎幺樣的方法來(lái)減小輸入端的噪聲干擾 答：Yiming濾波，選出有用信號(hào) 問：jimmy88531儀表放大器中外圍器件的精度（如電阻誤差）會(huì)不會(huì)影響測(cè)量精度，怎樣解決這一問題？ 答：Forest一般儀表放大器需要一個(gè)外部電阻來(lái)調(diào)整增益，電阻的溫度系數(shù)和內(nèi)部電阻不匹配的話，會(huì)造成精度的影響。A

19、D8221 內(nèi)部的電阻是負(fù)的溫度系數(shù)。 問：lijin_as通常單電源儀表放大器輸入電壓和電源的差值最小為多少？當(dāng)AD623 電源為3.3V時(shí)，是否能接受最大2.5V的輸入（輸出 Vo=1/2 Vin=1.25V）? 答：MariahIt depends on the internal design of the amplifer. For AD623, the input voltage can be from -Vs-0.15 to +VS-1.5. For 3.3V power supply, it is -0.15V to 1.8V. 問：lijin_as

20、能否給一個(gè)AD8250數(shù)據(jù)手冊(cè)的鏈接，從ADI網(wǎng)站上找不到 答：Yiming是預(yù)發(fā)布版，大概06年3月份有樣片。 問：mxslgyb我想將±2.5V（±5V、±10可選），080Hz模擬信號(hào)變成差分信號(hào)輸出，請(qǐng)問采用ADI的放大器有典型電路嗎？ 答：Jingyou can use our AD8133/9 to transform signal end signal to differential signal. You can also use our AD8222 to realize it .Remember to use +/

21、- power spply with enough headroom. 問：hzplq對(duì)多路微信號(hào)（如64路）如何采用儀表放大器 答：Forest儀表放大器輸入阻抗一般都比較高，所以比較適合微信號(hào)的處理。對(duì)于多路信號(hào)的處理，前端先可以采用多路開關(guān)（漏電流要考慮），再采用儀表放大器。 問：sjmww1127在遇到特別微小的信號(hào)時(shí),比如只有微伏大小,這個(gè)量比運(yùn)放的失調(diào)都要小,是不是就會(huì)被運(yùn)放淹沒,這方面不是很明白,請(qǐng)專家給予講解. 答：SteveIf the input signal is very small, in the uV level, and t

22、he offset is bigger then the signal can be submerged by the offset. But if the input signal is AC then you may be able to condition this. Two ways to amplify this type of signal:use a low offset amplifier like the AD8230 or AD8553or synchronously modulate the signal and make it an AC signal using sw

23、itches or an AD630 and then you can make the small signal AC and condition it. 問：ljd166我如何準(zhǔn)確地計(jì)算AI內(nèi)部前端的兩個(gè)運(yùn)放的輸出點(diǎn)的電壓值？ 答：JingVo+=(Vin+ -Vin-).RF/RFG+Vin+Vo-=V- -(Vin+ -Vin-).RF/RG 2005-12-14 10:55:19問：T4T4T4運(yùn)放單電源應(yīng)用后,信雜比是否會(huì)下降很多.我在視頻應(yīng)用中,改單電源后,會(huì)下降10多db，應(yīng)該是有問題的吧？ 答：EagleNormally it"

24、;s caused by the vertual GND (at VCC/2 by 2 resistoers). Add more decoupling capacitors will be helpful. Use an Voltage reference such as ADR381 will be better. Please also pay attention to the video amplitude, it will be clipped if too big (Ie. ADA4862-3, input common mode range is 14V at 5V power

25、supply, if signal plus commone mode level is lower than 1V or great than 4V, it may be clipped). If you use Rail to Rail Video amplifier (AD8091, ADA4851), it will be better. 問：dragon668899惠斯頓電橋輸出2毫伏/v的信號(hào)，進(jìn)行線性放大，實(shí)現(xiàn)軌對(duì)軌輸出，12伏單電源供電，能否提供性價(jià)比高的解決方案。 答：Forest你可以采用AD8221作為信號(hào)的前端處理，但如果你比較關(guān)心溫度漂移的話， A

26、D8230也是不錯(cuò)的選擇。另外，采用分立的方法一可以達(dá)到高精度， AD8671是我們高精度的運(yùn)放，噪聲很低，比較適合你12V的電源供電。 問：kevinlee你們有在高頻上應(yīng)用的呀？如何抑制干擾 答：Yiming對(duì)高頻段應(yīng)用，ADI提供差分放大器，比如AD8351, AD8138, AD8139. 一般用濾波的方式抑制干擾。 問：qiyuAD8221能工作的最高頻率是？ 答：Jingit"s 825KHz gain=1 typically 問：benyimi前面提到匹配電阻引來(lái)的共模信號(hào)干擾,如果要放大nv高頻信號(hào)如何處理? 

27、;答：MariahHow high is your frequency. For nV signal, you need to select very low noise amplifier. For example, AD8139 is a very low noise part with differential input and output. 問：mxslgyb如何將2.5V或5V單端輸入變成差分輸入，并且使正負(fù)極輸入無(wú)時(shí)差 答：JingYou can use AD8139/3 to do that 問：wactdADI的專家，你們好！我想請(qǐng)問放大器使用

28、單電源供電和雙電源供電有什幺不同嗎？對(duì)性能有什幺影響？ 答：SteveIt depends on whether there is enough headroom. Many instrumentation amplifiers are designed for +/-15V supplies. You can run them on lower supplies such as +5V but you will have very little head room. So you cannot use high gain or you have limited input volt

29、age range. The amplifiers that are rail to rail are better for use on low voltages such as +3.3V or +5V. If you do not have enough headroom, you do not have much input or output range. So there are some performance limitations. As long as you have enough head room, you can use the in-amp in single o

30、r dual supply. 問：motaiping儀表放大器的差分輸入,和傳感器配合使用時(shí),如何設(shè)定輸入偏置電路?電阻數(shù)值如何選取? 答：Forest采用儀表放大器的偏置電路，一般由你的供電電源來(lái)決定，推薦你選取VCC/2。電阻值由你需要的放大倍數(shù)來(lái)決定。 問：ljd166如何計(jì)算儀放內(nèi)部的BUFER，A1，A2兩個(gè)運(yùn)放的輸出電壓？ 答：JingA1 output  Vo+=(Vin+-Vin-)RF/RG+Vin+A2 output  Vo-=V-(Vin+-Vin-)RF/RG 問：shu_chen

31、我想問一下，如果我們需要對(duì)信號(hào)加入Dither以改善ADC的性能，在儀表放大器或者差分放大器中，應(yīng)該如何引入比較合適？ 答：Yiming加入diter能夠提高SFDR性能，但是降低了SNR。詳見AN-410 問：xsj19810419如何輸入保護(hù)？ 答：EagleWe can use Protection Diode to protect the input, but need pay attentaion to the impendence. Some device (such as AD629, +/-270V common mode range) can w

32、ork at high common mode voltage itself. 問：motaiping儀表放大器和傳感器配合使用時(shí),如何進(jìn)行調(diào)零? 答：Forest儀表放大器一般由一個(gè)REF管腳，采用不同的DC電壓，可以調(diào)整輸出的直流電平。我們建議在軟件中進(jìn)行調(diào)零，這樣比較靈活。 問：Jeff.Liu請(qǐng)問：AD8221儀表運(yùn)放能識(shí)別放大的電壓信號(hào)的最下限是多少？ 答：MariahIt depends on the noise performance of the amplifier. Otherwise, your signal will be subm

33、erged by the noise of the amplifier. 問：motaipingAD8221的輸入共模電壓范圍有多高?它的大小對(duì)儀表放大器的性能有何影響? 答：Jingit"s -Vs+2 and +vs-1.2. It"s not correlate with the performance of IN-AMP. But you should combine it with your gain,output range etc. 問：seawolf0718請(qǐng)問如果在單電源的情況下,在REF端加一個(gè)直流偏置,那幺輸出是不是VIN

34、*GAIN+VREF? 答：Forest沒錯(cuò)，不過你要考慮你所加的直流偏置的驅(qū)動(dòng)能力。 問：huaqun在ECG檢測(cè)中,第一級(jí)增益一般設(shè)置為多少? 答：Wenshuai第一級(jí)增益的大小受限于儀表放大器的動(dòng)態(tài)范圍和電極極化電壓差。一般需要考慮極化電壓差為300mV.所以如果用AD8221,供電電壓為+/-3.3V,那幺放大倍數(shù)在6倍左右。如果用AD8220，因?yàn)槭擒壍杰壿敵觯苑糯蟊稊?shù)會(huì)必AD8821大。更具體討論可以發(fā)郵件到china.support. 問：myrolite儀表放大器的RF濾波器組件參數(shù)的選擇有些什幺原則?有計(jì)算方法嗎? 答：

35、Yiming請(qǐng)參見ADI儀表放大器應(yīng)用指南RFI一節(jié) 問：qiyuAD82系列那種芯片可工作于30M以上？ 答：Yiming請(qǐng)用AD8138,AD8139, AD8351. 問：Jeff.Liu1.>儀表運(yùn)放主要適于處理哪些信號(hào)（電壓，電流，微小信號(hào)）？2.儀表運(yùn)放與普通運(yùn)放相比有哪些優(yōu)缺點(diǎn)？3.我現(xiàn)在要處理放大一10UV以下的電壓信號(hào)，能直接用儀表運(yùn)放嗎？ 答：Mariah1. Voltage, current, small signal should be OK for IN-AMP. 2. In-amp has large input imp

36、edance, large CMRR and it features differential input.3. Yes, you can. 問：ljd166儀表放大器的輸入端是否要考慮阻抗匹配？是否也要像運(yùn)放一樣匹配？ 答：MariahI don"t know what kind of impedance matching you refer to. In-amp has very large input impedance and small output impedance. 問：motaipingADI的單電源儀表放大器有那些型號(hào)?在應(yīng)用時(shí)直流輸

37、出電平如何精確地調(diào)整到電源的一半? 答：JingWe have  lots of this kind of IN-AMP such as AD8221,AD623/7/9,AD8222,AD8220,AD8250. You should terminate the REF pin to the middle of your power supply . But you should use a low impedence output voltage to bias the REF pin. For example if you use 0-5V power su

38、pply,you can use a 2.5V reference followed with a op-amp(gain=) to drive the REF pin. 問：ynh使用多個(gè)串聯(lián)后，帶寬是否降低？壓擺率是否變低，和噪聲是否按指數(shù)增大 答：SteveThe slowest PGA will influence your bandwidth and slew rate. So for example if you have 2 PGAs with 10MHz (30V/us) and 1 PGA with 1MHz (1V/us), your bandwidth

39、 and slew will be limited to the 1MHz (1V/us) PGA.Noise will increase. If you have 3 PGAsPGA_A with 10nV/rtHz then PGA_B with 10nV/rtHz and PGA_C with 10nV/rtHz and all the PGA are at a gain of G1, G2 and G3, then referred to input you will have(10nV/rtHz*G1)2 + 10nV/rtHz)*G2)2 + 10nV/rtHz)*G3)2)/(G

40、1*G2*G3)Noise is summed by its root sum square. 問：xsj19810419如何有效解決儀表放大器內(nèi)存在的潛在射頻整流問題 答：SteveYou can build an RFI filter at the input. There is an applicatio note, AN671. It is also important to keep the inputs as balanced as possible so that most of the signal is common-mode.You can also u

41、se ferrite beads or common-mode chokes (inductors) to stop the signal before it reaches the in-amp. 問：Jeff.Liu現(xiàn)在要放大一5UV的電壓信號(hào)，能直接用AD8221嗎？ 答：JingI think you can"t. Because the offset voltage of AD8221 is large than 5uV. For this kind of application you can use a chop amplifier such as

42、AD8628,AD8230 問：Guozhong我看了一些App. Note了解了如何在single surpply時(shí)放大,但是濾波怎幺做<可不可以? 答：Yiming單電源應(yīng)用時(shí)可以做濾波。 問：mxslgybwhat"s meaning "Rail to Rail"? Thank you! 答：Wenshuai軌到軌，也就是輸入或輸出的范圍與供電電壓的靠近程度。一般軌到軌輸入/輸出會(huì)跟供電電壓很靠近，大約可以到10mV左右。 問：unaffectedwhy not in-amp use different

43、ial output? This can make CMRR larger. 答：SteveYes. You can use differential outputs with an in-amp. The AD8221"s data sheet shows how you can make a differential output, Figure 51. We will also have a new in-amp, the AD8222 which can be configured for differential outputs.Most of the appli

44、cations in the market ask for single ended outputs that is why most of the in-amps have single ended outputs. But, we show in the data sheet and in some articles how to make a differential output. 問：eargle我在設(shè)計(jì)ECG的電路,請(qǐng)問AD620對(duì)RF的干擾在弱信號(hào)采集采用圖示的電路可能會(huì)有多大改善 答：Mariah使用如幻燈片29頁(yè)圖所示電路和0.01微法的電容 ，3 dB的

45、差分信號(hào)帶寬約為1900Hz。增益為5時(shí)，采用1V p-p的應(yīng)用信號(hào)，在10 Hz20 MHz的頻率上，測(cè)得電路的輸入端直流偏移的漂移小于6微伏。在單位增益的情況下，沒有直流偏移的漂移。問：ljd166我們選擇了AD623，但是如何解決溫漂問題，除了選擇低溫漂的儀放，有沒有簡(jiǎn)單的方法消除溫漂 答：Eagle(1)Please check if you can use AD623BR. B grade has lower temperature drift.200 mV Max Input Offset Voltage (AD623A)2 mV/"C Max Input Of

46、fset Drift (AD623A)100 mV Max Input Offset Voltage (AD623B)1 mV/"C Max Input Offset Drift (AD623B)(2)Cnsider other parts such as AD8221BR (not pin to pin).25 V max input offset voltage0.3 V/°C max input offset drift.(3)Input offset drift will be different with different gain. (4)Lower down

47、 other device"s temperature drift will also help to lower down the system temperature drift. Choose low drift resistor if you have serial input resistors for protection purpose.問：zcw0707如何用運(yùn)放精確平移直流電位，比如從8V移到2V，但這個(gè)8V是變化的，6V是確定的。 答：Yiming請(qǐng)檢查一下你的問題。謝謝 2005-12-14 11:13:34問：都市劣人基于成本考慮，用3個(gè)通

48、用放大器搭儀用放大器是否合適？ 答：MariahYes, if cost is the most concern. 2005-12-14 11:13:58問：gostray我把微弱信號(hào)用AD8304放大后,當(dāng)與計(jì)算機(jī)控制板接上后發(fā)現(xiàn)其噪聲變大,不知是什幺原因?是否換用其它儀表放大器會(huì)有好處? 答：JingIt"s very hard to clearify it what"s wrong with it.Because you just provide us  a little information.  

49、;In fact,if you use AD8304 to interface with a photo diode,it"s a good selection, the optical power could be less than -70dbm. I think you should pay attentaion to the bias circuit of AD8304. please call 800 810 1742 to give us more information. 2005-12-14 11:14:05問：hugoliang儀器放大器與普通運(yùn)放的區(qū)別.

50、謝謝 答：Forest儀表放大器是由三個(gè)運(yùn)放，和一些集成的電阻組成，具有比較高的輸入阻抗，和很高的共模抑制比。普通運(yùn)放要組成儀表放大器的話，由于運(yùn)放和電阻的不匹配，會(huì)有很多性能的損失。 2005-12-14 11:14:29問：peng-kai原先ADI公司的AD620運(yùn)放都作為了醫(yī)療生物電放大處理的典范，現(xiàn)在，ADI公司又推出的取代芯片在這方面的處理上是否增加了更好的或優(yōu)于以前的芯片的方法或其它呢，請(qǐng)列舉！ 答：ForestAD8221 就是比較好的新的儀表放大器，他的輸入阻抗，共模抑制比都有很大的提高。 2005-12-14 11:15:47問：T4

51、T4T4儀表放大器的輸入級(jí)在PCB布局時(shí)應(yīng)要注意什幺問題,才能有良好的噪音性能? 答：SteveYes. You should be aware of what size resistors you use at the inputs. Use wide traces at the supply pins and use decouple caps. Sometimes noise from the power supplies can cause spurs to show up at the in-amp. 2005-12-14 11:16:30問：jacklee200

52、8如何從儀放的輸入電壓電流噪聲的指標(biāo)來(lái)計(jì)算出要測(cè)量的微弱信號(hào)的最小值? 與普通運(yùn)放有區(qū)別嗎? 答：MariahWe recommend you to read the reference manual "Designers_Guide_To_In-Amps_2edition". There should be very detailed calculation in it. The book can be downloaded from the website. 2005-12-14 11:17:04問：hyjlm能否給出一個(gè)儀表用的長(zhǎng)時(shí)間積分電路?選用

53、什幺放大器?AD的高輸入嶄波自穩(wěn)零器件有什幺型號(hào)? 答：EagleIf you need long time in intergration, please choose low bias amplifiers such as AD8610. Also choose low leakage capacitor.AD8551/52/54, AD8628 are good chope auto zero amplifiers. AD8555 can adjust gain. 2005-12-14 11:17:41問：myrolite儀表放大器的輸入端是否需要進(jìn)行保護(hù)?如何進(jìn)行?

54、 答：JingSometimes you should add a input protection if your input common mode voltage could be larger than the IN-AMP common mode voltage. You could add shortkey diode or ues resistor divider or use voltage bias circuit to do that. 2005-12-14 11:17:52問：zhangxkADI是否提供應(yīng)用設(shè)計(jì)中的技術(shù)解決方案？ 答：Mar

55、iahWhat kind of the application? You can contact the local office to know more information of the solution related to your application. 2005-12-14 11:17:57問：wz623醫(yī)療應(yīng)用中的所謂“右腿驅(qū)動(dòng)”電路如何設(shè)計(jì)，就是從INAMP的RG處引出到人體參考電極的提高CMRR的電路。 答：MariahYou can find the righ leg driver circuit in the datasheet of AD620

56、 and AD8221. 2005-12-14 11:18:25問：waterbird放大器的接地處理是相當(dāng)復(fù)雜的，對(duì)于高精密儀表放大器，是否對(duì)電源地平面的鋪設(shè)有特別設(shè)計(jì)要求？ 答：JingOf course , you should pay attentation to the granding issue. You can use a ground layer to terminate the AGND and DGND . somethimes you should also use a guard ring to protect the input signal o

57、f the AMP. It"s a big topic for your question and I can"t interprete it very clear here.Please call 800 810 1742 for more information. 2005-12-14 11:22:03問：ljd166我們選用了AD623在16BIT的AD采樣，是否ADI可以推薦一些詳細(xì)的PCB LAYOUT的資料給我們，或者推薦一些相應(yīng)的書籍，資料？ 答：MariahAD623 is not very good for 16 bits system

58、 in terms of the noise performance. We recommend you to use AD8221. 2005-12-14 11:22:30問：singer533目前的儀用放大器最高精度可達(dá)多少? 答：MariahWhat accuracy spec do you mean? Offset? Noise? 2005-12-14 11:23:18問：mxslgybHow can I make the differential input to single output? 答：SteveTo make a differen

59、tial input to a single ended output, use an in-amp, such as the AD8221, AD623, AD620. It takes a differential input and outputs a single ended output. 2005-12-14 11:23:57問：wangqf2422AD745作為（水聽器）前置放大器使用為降低功耗，采用-5V+5V供電對(duì)于放大信號(hào)有什幺影響？輸入阻抗過高比如大于500兆歐姆，可以幺？如何消除前置放大電路產(chǎn)生的噪聲？ 答：Yiming最低工作電壓為+/-4.8V，所以可以工作在+/-5V.這樣輸入處處信號(hào)的范圍變小。AD745的差分如入阻抗為10Gohm，遠(yuǎn)大于0.5Gohm。請(qǐng)用濾波的方法濾除噪聲。 2005-12-14 11:24:38