[問：callhxw] 如何評定一顆ADC非線性？丟碼？
[答：Jing] you can use ADC"s INL and DNL parameter to evaluate the non-linearity and you can also use ENOB parameter to check code loss. Thanks!Generally ENOB releated with ADC"s SNR [2006-2-28 10:32:08]
[問：吉星] 在差分輸入時，不考慮直流，使用差分放大器和變壓器哪個更好．
[答：Mariah] Transformer is better for the better noise and distortion performance, especially in very high frequencies. [2006-2-28 10:32:14]
[問：Jane Yang] 請問應如何處理板級噪聲對于高精度AD的影響？特別是輸入部分的噪聲？
[答：Jing] This is a good question and it"s very difficult to answer. Generally, You should consider all the input noise derived from sensor/AMP/BUFFER. You can also use a LPF to reduce the input noise. Remember the BGP of AMP should be 100x of ADC"s throughput. Thanks! [2006-2-28 10:34:30]
[問：石林艷] AD變換的參考基準源很重要，對模擬供電電源和數字供電電源的要求也很高嗎
[答：Rui] 模擬供電電源，和數字供電電源相對基準源來說，精度要求相對較低，一般情況下用10uF的電容和0.1uF濾波即可。 [2006-2-28 10:34:31]
[問：zcs_1] 請解釋一下，分辨率和轉換精度之間的區別
[答：Mariah] For conversion accuracy, it involves many aspecs. For example, INL, DNL, offset, gain error. [2006-2-28 10:34:46]
[問：Leemour] 對不起能否講一下什麼是：RAIL TO RAIL，這個我一直不太明白。
[答：Xiangquan] 軌到軌指輸入軌到軌，或輸出軌到軌，具體指的是輸入信號或者輸出信號的范圍基本接近于電源，譬如電源是+-5V，輸入信號或輸出信號可以達到+-4.9幾V以上 [2006-2-28 10:35:25]
[問：jlwg] 很多種adi的a/d轉換器件都自帶有標準電壓源，請問是使用器件自帶的標準電壓源好還是另外使用獨立的標準電壓源更**？
另外使用ad7710時，每次轉換通道后的**次轉換結果是否是有效的？
[答：Troy] Use an independant reference to get the highest accuracy and lowest temperature drift. It depends on how much accuracy your application needs over temperature. [2006-2-28 10:37:14]
[問：xwlcba] 您提到驅動AD的運放增益帶寬積要求大于100倍采樣速率,請問對運放的轉換速率有何具體要求?
[答：Troy] To get the lowest distortion (THD), we recommend using an amplifier with at least 100x gain-bandwidth product greater than the sample rate. [2006-2-28 10:39:36]
[問：bly1979m] 本人***近做了一個項目用于**測量溫度的，就用到了這兩種器件！請**幾款貴司產品？并說說它的大概價格是多少？
[答：Jing] It"s depend on the accuracy of your system requirement. I am pleased to recommend that you can use our ADR421+AD7799. For price, you can check it on our web or consult our distributor according to your volume. Thanks! [2006-2-28 10:39:40]
[問：guahuahua] 選用AD7788時，能選擇的***適當的參考基準源是哪一款
[答：Mariah] You can try the software we recommended in the presentation "reference selection wizard". You can download it from the link of http://www.analog.com/Analog_Root/static/techSupport
/designTools/voltageReference/download.html
[2006-2-28 10:41:33]
[問：arzhiy] RC濾波器設計在ADC前就會出現相位漂移的情況，這樣采集到的信號是一個失真的，是這樣的嗎？
[答：Troy] The RC filter will not add any distortion to the signal. The RC filter will reduce noise at frequencies higher than its cutoff frequency. This improves ADC performance because it reduces out-of-band noise to the ADC input. [2006-2-28 10:44:33]
[問：yz_yjg] 我們的有一個雙通道數字示波器產品，當進行垂直移位時，即施加給AD9288的直流電平改變時，發現發現基中一個通道在LCD屏上的某些區域的基線變粗（這有規律，如每間隔16或32出現），有2mm到8mm左右不等，更換AD9288即可。大多數是其中的一個ADC有問題，我們希望基線在屏幕上移動時（不加信號），掃描基線的不要發生粗細變化，請問是什么原因？AD9288能**消除這種現象嗎？
[答：Mariah] We need to know more details about your circuit. Would you please send your question and schematic in details to china.support@analog.com, and then our engineer will help you on that. [2006-2-28 10:45:35]
[問：callhxw] 雙極性輸入信號，采用OP轉換為單極性的到ADC，設計時應關注哪些？
[答：Jing] First , you can select AD8129/AD8130 to realise the function. But this will reduce the ENOB. I suggest you use differential input ADC too. You should consider the noise from the AMP and the GBP of the AMP.You had better to select a high GBP and CMRR and low noise AMP. Thanks! [2006-2-28 10:45:35]
[問：Jane Yang] which reference is better: external or on-chip, for high speed (40~105M) and 12~14bit ADC?
[答：Troy] External references give better initial accuracy and lower drift over temperature. Using the on-board reference or an external one depends on the accuracy you need in the application. Generally speaking, the higher the ADC resolution (# of bits), the more likely you will need an external reference. [2006-2-28 10:46:16]
本文版權歸版權所有人所有，本站采用的非本站原創文章及圖片等內容無法一一聯系確認版權者。如果本網所選內容的文章作者及編輯認為其作品不宜公開自由傳播，或不應無償使用，請及時通過電子郵件或電話通知我們，以迅速采取適當措施，避免給雙方造成不必要的經濟損失。引用出處：
https://blog.csdn.net/wzk456/article/details/39295999
[問：liu.gy] 1、就ADI的產品而言，請給出“基準電壓源+ADC”的兩種方案：分離與集成 兩個方案的優缺點？
2、運放到ADC之間什么時候需要加濾波處理？如果加濾波處理，請給出濾波的方式及性能比較？
[答：Xiangquan] 1。集成主要帶來方便，但是往往由于工藝的限制往往不能發揮轉換器的**性能，如果選擇合適的外部參考源，則可以比較好的發揮轉換器的性能
2。運放與AD之間的濾波主要為的是濾除噪聲，抗混疊，以及給ADC的轉換產生的瞬態能量提供緩沖，一般一階RC低通濾波即可，或者對于帶通濾波，可以根據自己的要求進行設計 [2006-2-28 10:46:34]
[問：chenhaifeng] 放大器的PSRR是否與外電路及輸入信號無關？
[答：Haoran] PSRR主要是電源對信號的影響，與外電路和信號無關 [2006-2-28 10:47:12]
[問：hzluoping] 請問：1）精密ADC的數字地和模擬地的正確接法及對ADC轉換精度的影響？
2）在單片機系統應用時，對精密ADC的啟動和數字信號的輸出的控制
有何要求？
[答：Jing] 1> you should consider the system current. If the digital current is small, you can seperate digital GND and analog GND and combine them together in one point. If the digital current or noise is very large, you can also look ADC digital GND as analog GND.
2>I don"t know what you mean. Generally ,some of our ADC has hardware start and software start selection. [2006-2-28 10:48:39]
[問：arzhiy] 常用的RC往往本生噪聲也很大，這樣且不是更加增加了采樣的噪聲？
[答：Haoran] 噪聲主要來源于電阻，實際上在可能的情況下或電路穩定的前提下，盡量增大電容可以提高噪聲性能。 [2006-2-28 10:48:50]
[問：boclandc] 我采用了AD7671,測試8通道的線性電子尺(等效線性電阻),請問有什么好的多通道切換,我采用了二片MAX4052后面通過AD620做驅動,但是切換***穩定時間需達10uS,在切換速度上非常不理想.不知貴公司有否這樣的方案,使切換速度小于或等于2uS?謝謝!!
[答：Mariah] ADI has many new mux and switches which has better performance, like ADG121x, ADG13xx and ADG14xx. Also the settling time also depends on your circuit. You can send your schematic and question to china.support@analog.com. Our engineer can analyze your circuit and give out the solution. [2006-2-28 10:49:42]
[問：ecnanjing_EBY7E] 請問,電壓基準的精度和溫度系數對AD的精度的影響的換算關系是怎樣的?
[答：Haoran] 你可以在今天的資料中找到，并且可以從我們的網站上下載 [2006-2-28 10:50:00]
[問：hzluoping] 模擬地和數字地的接法對ADC影響大，如何作好接地？
[答：Rui] 地的接法一般有兩種，1。把地平面分割為模擬地和數字地，或者一層數字地，一層模擬地，然后共同接到共地點。2。不分割模擬和數字地，使用多點接地。
對于**種情況，注意數字地層和模擬地層不能重疊。
對于第二種情況，要提供盡量多的接地點。 [2006-2-28 10:50:14]
[問：amatist] 基準源有齊納二極管和帶隙電壓基準等幾種,它們有何優缺點?
[答：Troy] References built using bandgaps have lower temperature drift, but they are more complicated and more expensive. Zener references are usually less expensive, but have more noise and may have lower initial accuracy and higher drift over temperature. [2006-2-28 10:50:22]
[問：amatist] 對電壓基準源的要求主要有那些指標?如何選擇電壓基準源?
[答：Jing] Intinal accuracy, temperature drift is two of the key factor. You can according to your system error requirement and download our REF+CONVERTER wizard to select the corresponding REF. Thanks! [2006-2-28 10:50:22]
[問：elmer] 放大信號中出現大的脈沖信號，怎樣去除這個信號？
[答：Haoran] 你可以先在運放前增加低通濾波器。 [2006-2-28 10:51:00]
[問：wzj0713] pA~mA的高動態低變化速率輸入的信號調理擬使用ADI產品ad8304，現在需咨詢的是如何***小限度的減小引入噪聲（從PCB版圖、工藝和電路處理兩方面）。
[答：Jing] You can use AD8304 to interface a PIN and converter current to voltage. To minize the input noise, you should select a better PIN--this is the first noise source. Then you should select high accuract resistor and capacitor . Of course, multi layer PCB is better to minize the inout noise. [2006-2-28 10:53:35]
[問：yz_yjg] ADI有沒有可編程的基準電壓源?型號?
[答：Troy] We do not have a digitally programmable voltage reference today. The AD8555 is a digitally programmable instrumentation amplifier with a built-in voltage reference. You could use this just as a programmable voltage reference by grounding the +IN and -IN pins. [2006-2-28 10:54:40]
[問：hanxin] 在使用ADI的AD轉換器的時候,如何確定是否需要前端的運放? 如何根據不同的AD確定需要哪一種運放?如何處理前端的RC ? 是否可以分別就AD7865和AD7656來說明?
[答：Haoran] AD7865是14bit的ADC，輸入端為低阻，所以前端必須選用雙極性的運放。整個帶寬內的噪聲要滿足14比特ADC的要求。OP497/OP4177是不錯的選擇。
AD7656是16bit的ADC，輸入端為高阻，所以模擬前端可用高性能的雙極性運放，也可以不用。但我們建議采用，這樣信號的完整性比較好。當然運放的選擇，電路的設計要滿足噪聲要求。OP4177/AD8674是不錯的選擇。 [2006-2-28 10:56:03]
[問：zcs_1] Ad8138使用應注意哪些地方，好像電阻不能設置很大的阻值？
[答：Jing] AD8318 is our RF LOG-AMP. I don"t know which resistor you are mentioned. For better performance, you should pay attentation to the impedance match of input/output circuit. This is the very important factor. [2006-2-28 10:56:11]
[問：hanxin] 選擇基準的時候,我們主要需要看那些參數?哪些參數決定一個基準是比較好的?
[答：Troy] Initial accuracy is the easiest spec to compare. Temperate drift in ppm/C is also important. If you are using a portable application, supply current will be important. For 16+ bit ADC applications, the output noise is also important. [2006-2-28 10:56:46]
[問：shandong] 降低噪聲的主要措施和手段都有那些?并且比較經濟和實用的有那些?
[答：Xiangquan] 不確定您的應用場合是什么，總體來說，你可以：1.選擇高性能的器件，2.對感興趣的帶寬進行濾波，3.模擬地和數字地的分割(layout issues) [2006-2-28 10:57:20]
[問：zrg175] 請問用電感進行濾低頻的話，電感的值怎樣選擇，有什么規律嗎？謝謝！
[答：Rui] 一般情況下，電路中使用電容濾波，高通濾波器的截***頻率為1/(2Pi*RC).
如果您有特殊需要，必須使用電感進行濾波，請把具體的情況和問題提供給 china.support@analog.com 尋求更詳細的幫助 [2006-2-28 10:57:25]
[問：luyisa] 在多通道測量中，模擬開關出來的信號是否能直接進ADC?若中間要接運放的話，對運放的要求有什么？
[答：Jing] Yes , you can interface MUX and ADC together. if you want to get better performance, you can add AMP before the MUX for every channel. [2006-2-28 10:57:51]
[問：石林艷] 怎樣提高A/D變換的有效位數，尤其對高頻的變換？
[答：Haoran] 在選定一定位數的ADC之后，前端信號的處理要滿足精度要求，參考電壓的噪聲要盡量的小，對于高速ADC,時鐘的精度也是要考慮的重要因素。 [2006-2-28 10:58:34]
[問：xiexinpo] 請問：對于AD9235BRU-40,選擇3.3V單電源，用AD8137做前級緩沖并轉換成差分輸出（1.625V 參考電壓），然后用AD8330ARQ做增益調整是否可行？應注意哪些問題？是否要增加低通濾波器？其低電壓電源對于模數轉換器的線性和動態范圍有多大的影響？謝謝！
[答：Mariah] There would be no problem for use the combination of these parts. For low voltage application, use rail to rail output amplifiers will increase the dynamic range. As you know, AD8330 is a rail to rail output amplifier. There should be a anti-aliasing filter before the ADC. You can find the typical connection of the AD8330 and ADC. You can just add a R-C filter between AD8330 and the ADC. [2006-2-28 11:00:56]
[問：tjshen] 高精度ADC、電壓源和放大器的**穩定性的測量方法及其設備的要求。
[答：Troy] We characterize at least 300 units for 1000 hours before qualifying a product family released for sale. Offset voltage is measured before the 1000 hours and after the 1000 hours. The difference in offset voltage is the drift. We calculate long-term drift based on these numbers. Stability is verified on the bench by observing the output voltage with an oscilloscope. [2006-2-28 11:01:04]
[問：caitouc] 精密應用時是否需要對電源50Hz進行濾波?如何實現?
[答：Xiangquan] 一般心電信號（mV級信號）、腦電信號（uV級信號），以及一些小信號的測量需要進行工頻抑制，因為工頻信號往往可以引起伏級干擾；如果對50Hz進行濾波，主要有軟件和硬件的方法來實現notch filter，也可以利用提高系統的共模抑制比(CMRR)來實現。 [2006-2-28 11:02:38]
[問：arzhiy] 對于24bitADC我們一般選取什么樣的基準源，例如采用AD公司的哪個型號？
[答：Troy] I recommend the ADR420 family. [2006-2-28 11:02:53]
[問：Jane Yang] To evaluate your AD, such as AD9236, what kind of clock source and signal source should be equiped? could you give some examples?
[答：Jing] For clock, you can use ADF4360-X or ADF411X+VCO or AD9510+VCO . For signal source , you can use some instrument such as rohde-schwarz company"s instrument . [2006-2-28 11:03:01]
[問：engronger] 運算放大器有時候會有溫漂的現象,請問調整溫漂有什么好的辦法?
[答：Haoran] 對于普通運放，你可以看到Offset Drift這個參數，他的大小代表了溫漂。當然，你還可以選用我們zero drift的放大器，AD8628/9/30是目前**的放大器。 [2006-2-28 11:03:57]
[問：lsqbank] AD轉換芯片的Gain Error，一般***壞情況都能達到0.25%FSR，請問，如何減小這一誤差，Gain Error Match是否是在已經進行調整后，AD芯片的Gain Error所能達到的**性能？
[答：Mariah] Generally speaking, gain error is a linear error. So you can use calibration to remove this error. The main concern of using the ADC is the gain nonlinearity error. Nonlinearity error is difficult to remove. [2006-2-28 11:04:30]
[問：ecnanjing_EBY7E] 雙極信號轉為單極信號要引入直流分量,對AD的精度有無影響?
[答：Troy] Not if you use an instrumenation amplifier. If you use external resistors, the accuracy is only as good as the resistor matching. [2006-2-28 11:04:40]
[問：zcs_1] 請問如何根據設計來選擇合適的位數的AD或DA芯片
[答：Rui] 主要是根據您的系統所需要到頻率和精度所決定的。
首先確定信號的工作頻率，選擇能夠滿足采樣速度的AD或DA，
其次確定信號的幅值，選擇能夠提供足夠輸入/輸入范圍的ADC，同時可根據需要的精度或允許的誤差范圍選擇放大器的位數。
還有輸入/輸入為差分或者單端，輸入的信號的路數，有無內置參考源，內置緩沖等等都可以作為選擇的標準。 [2006-2-28 11:04:51]
[問：kivin_G] 現在的電壓基準源**電壓能達到多低?有沒有電壓為0.6V的電壓基準源?
[答：Troy] Usually about 1.2V. I am not familiar with a 0.6V reference. You could use a forward-biased diode to generate 0.6V to 0.7V. [2006-2-28 11:05:46]
[問：sxfs1984] 如何降低運算放大器輸出的波紋?應該考慮那方面的因素?
[答：Haoran] 首先你要先考慮這個紋波是從哪里來的，然后再確定在怎么處理。 [2006-2-28 11:06:26]
[問：ecnanjing_EBY7E] 請問放大器的相位失真如何控制?
[答：Mariah] you can use compensation circuits to do that. [2006-2-28 11:07:06]
[問：amatist] 向多個電路提供基準電壓源時,如何擴充基準電壓源的輸出能力?
[答：Troy] One way to increase output current is to use a unity-gain buffer at the output of the reference. This is a very common technique for improving the reference output drive. [2006-2-28 11:08:21]
[問：sxfs1984] 什么情況下要選擇隔離放大器?如何選擇?
[答：Mariah] When there are potential high voltage difference between two sides, you need to isolate them. For example, medical applications, motor control applications. [2006-2-28 11:09:32]
[問：hzluoping] 對直流納級弱信號放大時，增益帶寬積問題如何看
[答：Rui] 一般情況下，對于小電流信號，放大倍數要求都會比較大，例如1000，如果信號頻率同時又比較高，就要注意增益帶寬積的限制的問題。
增益帶寬積為信號頻率和放大倍數的乘積，在選擇器件的時候要注意該數值不能超過放大器的給出的增益帶寬積參數 [2006-2-28 11:09:55]
[問：woodxp] 對于低頻信號也需要加抗混疊濾波器嗎？
[答：Mariah] Yes. [2006-2-28 11:10:05]
[問：htc703] 1.放大器的噪聲en的峰峰值(Vp-p)和有效值有聯系嗎？怎么換算？
2.在24-bit數據采集系統設計中應該注意哪些問題？
[答：Haoran] 1。Vp-p=6.6Vrsm
2。在sigma-delta ADC中，SNR是比較重要的參數。設計中主要應注意前端的處理，以及版圖方面的考慮。 [2006-2-28 11:10:07]
[問：bly1979] 1。請問目前性價比**的ADC是哪一款？大概價格是多少？
2。位數**的ADC是哪一款，多少位？大概價格是多少？
3。低功耗ADC是哪一款？**功耗多少？大概價格是多少？
[答：Jing] 1. It"s very hard to answer this question. It should according to your application such as your accuracy,error ,power supply,throughput etc.
2. Now we have 24bit ADC such AD ad7799 etc
3. AD7680 is a good selection for portable instrument---3mW
For price,please present your volume and consult our distributor our check it on our web. Thanks! [2006-2-28 11:11:10]
[問：lewisflame] **您好、主持人您好，ADC基準經過放大器驅動后，通過鏡像結構輸出基準電流，每一對鏡像管的版圖是不是**使用相同的單條尺寸：W不匹配會不會增大失配？
[答：Troy] Yes. It is a good idea to use the same metal width.W不匹配會會增大失配 [2006-2-28 11:11:31]
[問：xiexinpo] 自動校零放大器對ADC的噪聲有多大影響？
[答：Troy] Auto-zero amplifiers have slightly more noise than non-auto-zero amplifiers. In many cases, the noise will still be much lower than 1LSB. Many customers use auto-zero amplifiers and do not have any problems with noise. Auto-zero amplifiers have no drift over temperature and almost zero offset voltage. I recommend using them when possible. [2006-2-28 11:15:06]
[問：woodxp] 在ADC前加RC濾波，不會影響ADC的性能嗎？因為ADC一般有采樣保持電路，在其前面并上一個電容，則會影響其采樣保持時間吧？
[答：Haoran] 加RC濾波不會影響ADC的性能，相反還會提高它的性能和穩定性。ADC內部一般有采樣電路，外部的電容可以在每次采樣的時候提供快速的充放電，提高它的精度。一般ADC外部都會有運放來驅動，所以電容不會影響保持時間。 [2006-2-28 11:16:35]
[問：shandong] 為了降低噪聲在布PCB板方面應注意那些問題.
[答：Troy] I suggest using a 4-layer board. One internal layer is ground, and the other internal layer is power. We recommend using separate digital and analog ground and power planes. Many times, you can use a split plane to keep digital currents separate from analog currents. This greatly improves noise performance. [2006-2-28 11:17:11]
[問：cola] AD８０３１是一個很好的信號調理運放，它具體可以實現哪些調理？
[答：Haoran] AD8031信號帶寬和噪聲參數都比較好，所以可以作為前端信號的處理以及參考電壓的驅動。 [2006-2-28 11:17:48]
[問：ddac87] 放大電路的頻寬問題: 我們知道引入負反饋可以拓展放大器頻寬. 那如果OP-AMP的BW是3MHZ, 是否用這OP-AMP構成的放大器的頻寬可以達到更寬,如4MHZ ?
[答：Mariah] I don"t think using the negative feedback can make the bandwidth of the amplifier larger. [2006-2-28 11:18:06]
[問：pulan] 請問有沒有輸入范圍為0-10V的差分12BIT的AD
[答：Mariah] What is the sample rate you want? [2006-2-28 11:18:19]
[問：hzluoping] 降低基準電壓是否能提高分辨率
[答：Haoran] 不可以，ADC的分辨率一般都是相對于它規定的參考電壓。 [2006-2-28 11:18:29]
[問：gsdiscover] 我使用的AD620，設定的放大倍數為10倍，對于正輸入信號，輸入輸出之間關系非常線形，效果很好，可是負向信號輸入時，小信號（0.08V以下）時放大效果也很好，線形度也行，但是信號強度超過0.08V時,其輸出就不再發生變化，始終是0.823V左右，好像是放大后的信號被斬波了,出現了失真，我的供電電壓為+-12V，輸出5腳REF接地了，請給出解決辦法？？
[答：Mariah] What is your input common mode voltage? [2006-2-28 11:19:28]
[問：ecnanjing_EBY7E] 在做環保測量設備中,通常前端的信號多是pA級的,請問選用AD什么樣的放大器***為適合?
[答：Troy] The AD8691 is an excellent amplifier for many applications. [2006-2-28 11:19:29]
[問：zcs_1] DA后面的抗混疊濾波器怎么設計效果會比較理想？
[答：Jing] It"s depend on your application such as the Fc or BPF bandwidth and settling time. You can use our web fliter design tools to select your corresponding filter . [2006-2-28 11:20:26]
[問：cqz] 我檢測行程傳感器,使用外部的線性滑動電阻,要求采樣頻率20K,分辨率12bit請問ADI有什么合適的解決方案?SPI接口的AD有么,此外運放與AD間的RC怎么選擇,它好像除了減少外部噪聲的擾動外也跟內部的開關采樣保持電容有關.上述要求麻煩給我個ADI的解決方案,包括基準源.性價比高些的.
[答：Xiangquan] I"m not sure your exact application, but for 12 bit, 20ksps sampling rate ADC, you can choose AD7920, which is a low cost ADC, doesn"t need external reference; For the low pass filter design, the simple one order RC filter is enough, which fc=1/(2*pi*R*C) [2006-2-28 11:20:29]
[問：sxfs1984] 怎樣解決數據采集或ADC中的電磁干擾問題？
[答：Troy] The best way to solve electro-magnetic interference (EMI) is surrounding the circuit with a metal shield. Keep all trace lengths short. Using a ground plane will also help. Where possible, use differential signals. Most ADCs today are differential input for this reason. [2006-2-28 11:21:46]
[問：life1313] Can you advise a device for me to replace ADC DEVICE of TVP5150A which is TI product
[答：Wenshuai] ADV7181 or ADV7180. 您給出更詳細的要求的話，我們可以給您選擇更合適的產品。也可以聯系800 810 1742 [2006-2-28 11:22:37]
[問：jiaguowei] ADC或DAC如何選擇數字地和模擬地的共地點，以減少數字地對模擬地的影響？
[答：Jing] You can seperate digital GND and analog GND if the digital noise is large. You can also look ADC/DAC"s digital GND as analog GND if the digital noise and current is very large . You can combine digital and analog GND together in one point. How to select the point is key . You can select the minimun digital current circul and analog circul and combine it here together. Thanks! [2006-2-28 11:23:51]
[問：吉星] ADC產品給出的數據參數ENOB與實際誤差多大
[答：Mariah] The ENOB is exactly what we measured. It depends on your system design. [2006-2-28 11:24:08]
[問：cola] 能否介紹幾種ＡＤＩ對高精度ＡＤＣ進行測試的方法？其優劣又在哪里？謝謝！
[答：Haoran] 對靜態參數，輸入直流信號要保持高精度，然后你可以測出INL，DNL還可以得到柱狀圖。
對動態參數，輸入交流信號要保持高精度，時鐘也要多考慮，做FFT分析，可以得到SNR和ENOB。 [2006-2-28 11:24:29]
[問：dengyt] 請問**,您對放大器溫度補償方法有何見解?
[答：Troy] It is very difficult to compensate an amplifier for temperature drift. Each amplifier is different. We suggest using a low-drift amplifier for precision applications. For example: AD8628 or AD8661. [2006-2-28 11:24:59]
[問：yz_yjg] 有沒有可能用分壓器或別的方法來獲得低電壓的電壓基準源?
[答：Haoran] ADI 有很寬范圍的輸出電壓，從1V到10V都有。 [2006-2-28 11:25:59]
[問：roboy] 我選用的AD轉換器是AD7457，這是一個差分輸入的轉換器，假設信號的驅動能力足夠強，我是否可以直接把外部輸入信號的信號地直接接到vin-，而信號接到vin+，從而不用差分運放？。
[答：Jing] If the input signal is large enough , you can do this. But I still recommend that you use a differential AMP that will promote CMRR and you can also condition your input signal commond voltage to the middle of the ADC input voltage and add some LPF to minimize noise. [2006-2-28 11:26:39]
[問：dengyt] 放大器的輸出短路保護能力如何?在設計上如何考慮過載能力?
[答：Troy] Most amplifiers have output short-circuit protection. This prevents the amplifier from damaging itself if the output is shorted to ground. Our engineers design special circuits to detect if there is a lot of output current. The amplifier turns off its output stage in such a condition. Output short-circuit protection is quite reliable. [2006-2-28 11:27:33]
[問：wzj0713] 我們現在有一個數字場強儀的設計，目前正在對信號的前級輸入作調理，輸入信號是一個檢波二極管采到的大尺度電流信號，向詢問如何將這一信號藕進我們的目標電路可以使小信號不被淹沒在噪聲里？
[答：Xiangquan] Could you please send the circuit and your questions to china.support@analog.com? thanks [2006-2-28 11:27:46]
[問：yanmings] 高輸入阻抗、低偏置電流的運放在使用時需要注意什么？調零電路是否必須？
[答：Jing] This kind of AMP always interface with current inout signal and you should also pay attentation to the voltage offset and BGP of the AMP. If you want to get better performance, you should add selt calibration circuit to minimize the Ibias both in software of in hardware. Thanks! [2006-2-28 11:28:54]
[問：luckywin] 差動放大器和差分放大器什么區別?差分放大器是用來干什么的,哪里有它的基本原理
[答：Rui] 差動放大器，Difference amplifer
可以在很高的共模電壓的差分信號中，提取出差分信號。傳遞函數為 Vout=(V+IN)-(V-IN)
差分放大器 Differential amplifer
指輸入/輸入均為差分信號的放大器。增益由外接電阻設置
對于差動放大器，請參考AD629數據手冊。對于差分放大器，請參考AD831*系列 [2006-2-28 11:29:12]
[問：jlwg] 我在做稱重系統時，電橋傳感器需要10v的激勵電壓，我的做法是把ad7710自帶的2.5v電壓源作為標準電壓源,并且將其接到運放op07的輸入上，經放大成10v后再接到傳感器上作為傳感器的激勵源。請問這樣使用可不可以？對轉換精度有無不良影響？
[答：Mariah] You can use OP07 to generate the 10V excitation voltage of the bridge. But you should think about the error which OP07 would bring, for example, temp drift. Also the current driving capacility of OP07 should be considered. If the output current of OP07 is not enough, you have to use a transistor to dirve. [2006-2-28 11:31:02]
[問：xurn] 請問有沒有２．５Ｖ的帶恒溫的基準源？
有沒有１８位以上的雙極性輸入、１００Ｋ以上的轉換速率的ＡＤＣ芯片？
達到１８位以上的精度，雙極性輸入轉差分如何實現？
[答：Haoran] ADR431 is 2.5V output reference.
until now, we have no bipolar input 18bit ADC, but you can use bipolar amplifier to attenuate signal to 0~5V, then use 18bit ADC. you can find schematic in this presentation, which can be download in ADI website. [2006-2-28 11:31:17]
[問：jnfxt95] 我用過AD7730信號調理器，用于衡器設計，性能指標非常好（特別是失調溫度漂移很小，比AD7710好很多）。但AD7730是1998年的產品，價格有些貴。ADI近幾年有沒有推出用于衡器的新產品？
[答：Mariah] AD7799 is the new product with high precision and highly recommended to use in weigh scale design. [2006-2-28 11:31:49]
[問：yanmings] 在弱信號放大器中，如何降低電源引起的噪聲？
[答：Jing] For small signal, You should select low Voltage offset and I bias AMP such as AD8528,AD8555 etc. If the power supply is the major noise source, I suggest you select a linear voltage source instead of switching power supply. You can also filter the power supply using Pi filter and de-coupler capacitor is very inportant, please select the low ESR capacitor in your application and ensure the voltage ripple less than 1/10 of your signal. [2006-2-28 11:32:27]
[問：hzluoping] 納伏級直流信號放大是的增益帶寬積如何計算
[答：Rui] 直流信號放大的時候不需要考慮增益帶寬積的限制。
增益帶寬積為信號放大倍數乘以信號頻率。 [2006-2-28 11:33:22]
[問：dengyt] 如何減少差分放大器的輸入信號干擾?
[答：Haoran] it is hard to understand you question. you can contact 800-810-1742 for detail explaination. [2006-2-28 11:33:37]
[問：石林艷] 時鐘的選擇用正弦波還是方波比較好？
[答：Mariah] Can you give the specific application? It would be different in different applications. [2006-2-28 11:33:43]
[問：engronger] 放大器有時會出現自激和來自外部的干擾,如何避免?
[答：Troy] If you are refering to electro-magnetic interference (EMI), the best way to avoid it is to enclose the circuit in a metal shield or box. Keep all signal trace lengths short and use a ground plane if possible. Transmit signals differentially to reduce any noise the traces pick up between the amplifier and the ADC. [2006-2-28 11:33:43]
[問：xiexinpo] 請問：在ADI的ADC Demo board 中有的模擬地和數字地用一只Ferrite Bead 相連，而有的則直接相連，這兩種方法區別又多大？那種更好些？謝謝！
[答：Jing] I think a Ferriet Bead should be better to monimize the interter between digital GND and analog GND. [2006-2-28 11:34:07]
[問：253760] 我用AD872做間隔性數據采集，需要AD采集時才給時鐘信號到AD872的時鐘端，比如連續給1K個5Mhz時鐘脈沖，前30個脈沖采集的結果總是不對，可能是什么原因?
[答：Xiangquan] you can try to keep the ADC continuously, it may be the ADC need time to set up [2006-2-28 11:34:35]
[問：hznetwork] 能否提供相關的技術資料以及設計案例
[答：Rui] 請問您需要相關什么的技術資料？如果需要更詳細的幫助，請打800-810-1742，或者發郵件到china.support@analog.com尋求幫助 [2006-2-28 11:35:09]
[問：pulan] 請**幾款電表計量芯片。介紹一下
[答：Jing] single phase:ADE7751/3/5
three phase : ADE7752/4/8
anti-theft: ADE7751/ADE7761 [2006-2-28 11:35:10]
[問：ypqecum] 如何對電壓基準源的溫漂進行補償?
[答：Troy] It is very difficult. Each part is different. We recommend using a low drift amplifier or low drift amplifier for precision applications. [2006-2-28 11:35:15]
[問：leontree] 選擇AD7789和779X時，能選擇的***適當的參考基準源是哪幾款
[答：Mariah] ADR43x, AD780. You can use the reference wizard tool recommended in the presentation to select the exact part which can meet all of your specific requirement. [2006-2-28 11:35:17]
[問：pulan] AD輸入前端是0-10V的信號，采用電阻分壓的方式會對精度有何影響？**有什么好的建議？
[答：Troy] The voltage will be as accurate as the tolerance of the resistors. 1% resistors will result in 1% voltage accuracy. [2006-2-28 11:37:01]
[問：pulan] 現在的AD芯片對靜電要求高嗎？還有焊接這些是否會對AD造成致命傷害？
[答：Xiangquan] almost all our parts have ESD protection in internal structure, soldering commonly can not destroy the parts, but we highly recommend you power off the soldering equipment during soldering [2006-2-28 11:37:03]
[問：roboy] ADI有沒有能對pA級弱電流進行放大的器件？謝謝！
[答：Haoran] AD8605/6/8 are good recommendation to you. [2006-2-28 11:37:11]
[問：caitouc] 24位ADC需要什么樣精度的基準電壓源?
[答：Mariah] The most concern is the temperature drift and noise performance. [2006-2-28 11:38:05]
[問：shandong] 請**幾款高精度高速度的ADC芯片?
[答：Mariah] Would you please give the specification in details. [2006-2-28 11:38:38]
[問：ypqecum] 如何消除EMI對基準電壓源的輸出噪音的影響?
[答：Troy] We recommend keeping the circuit inside a metal shield or box. Use a low noise ground plane underneath the voltage reference. Use a 0.1uF ceramic capacitor on both the input and output pins of the voltage reference. You can add an additional 1nF capacitor in parallel - smaller capacitors are better for reducing higher frequency noise. [2006-2-28 11:39:27]
[問：mayongtao] 請問ad6644用什么放大器來驅動？
[答：Jing] You can use AD8138 to drive it. Thanks! [2006-2-28 11:40:20]
[問：gsdiscover] 如果一個測試系統的傳感器輸出電壓范圍為0-0.5v,精度為0.5mv,采用12位A/D轉換器,應該選用的放大器增益為多少?
[答：Jing] If the input range of the ADV is 0--Vref, you can select a gain of 5 and Rail to rail amp to drive it such as AD8027 [2006-2-28 11:41:54]
[問：kivin_G] 電壓基準源流出和吸入電流的能力要留有多大的富余量?
[答：Troy] Very little. Most references require less than 1mA of supply current. Refer to the datasheet for supply current specs. [2006-2-28 11:42:27]
[問：shandong] 對于高速的ADC在布PCB板時,如何降低噪聲,**良好的精度.
[答：Mariah] You can send an email to china.support@analog. Then we can send the application note talking about the details of high speed circuit layout. [2006-2-28 11:43:04]
[問：boclandc] 現在我選用AD7655,輸入信號差分信號,現在我選用AD620做驅動AD7655,是否合理,有沒有更優的方案?謝謝!!
[答：Haoran] AD8221 is better one that can be replace AD620. [2006-2-28 11:44:37]
[問：kivin_G] 在并聯電壓基準源時,需要考慮的因素有那些?能否**一些適合并聯的電壓基準源產品型號?
[答：Troy] We do not offer any combined voltage references. I don"t know of any disadvantage to offering a combined reference. We just haven"t offered one before. [2006-2-28 11:44:39]
[問：callhxw] 使用外部基準源時，**為1.25V，而使用時采用1.2V，其他參數相同。請問能否達到要求？軟件處理如何？
[答：Mariah] First, you need to check whether the converter can accept 1.2V voltage input. In your software, you also need to change the full scale point. [2006-2-28 11:44:50]
[問：msshen2003] 選擇精密ADC器件的原則是什么？
[答：Mariah] Offset, noise, linearity and etc. [2006-2-28 11:45:47]
[問：engronger] 運算放大器在使用的時候會有零漂的現象,請問調整零漂有什么好的辦法?
[答：Troy] Use an auto-zero amplifier. AD8628 is an excellent choice. [2006-2-28 11:46:02]
[問：石林艷] AD6644基準參考源的輸入電流有要求嗎？
[答：Jing] No special requirement, there is a BUF in our AD6644 that will promote the deiven ability . [2006-2-28 11:46:07]
[問：woodxp] 直流信號和交流信號的采集中分別需要根據哪些參數來選擇合適型號的ADC如在高精度的低頻信號測量中和圖像采集需要怎么考慮？如何計算和測量實際電路中ADc的精度？ADc的精度和分辨率有何關系？在不考慮成本的情況下是不是量化位數越高越好？
[答：Xiangquan] For ADC selection, mainly according the signal BW and your precision requirements, for low speed signals, you can select sigma-delta ADCs if the precision requirments are high, for video applications, we have video ADCs and video decorders like ADV7180; For ADC precision measurements, you can measure the peak to peak resolution of your system, the ADC bits don"t equal precision, you can send a email to china.support@analog.com for these concepts [2006-2-28 11:46:28]
[問：gsdiscover] 我想問一下有什么方法能提高AD的動態范圍
[答：Jing] No better solution. One special ADC has it"s fixed maximum dynamic range according to it"s specifaciton and datasheet. Thanks! [2006-2-28 11:47:59]
[問：yuke] 你們哪的A/D可以低電壓工作嗎.耗電怎么樣,有沒有像MSP430的低功耗啊,可不可以給我幾塊A/D啊,我現在正想應用于張力控制,與溫度采樣.(:成功的話量大.
[答：Xiangquan] I"m not sure the voltage you require, some of our ADCs can work under very low voltage, like AD7466, which can work under 1.6v power supply, if you want to measure pressure and temperature, you can try AD7799, which is a low power dissipation part; for sample application, pleas visit www.analog.com for free sample request [2006-2-28 11:49:27]
[問：luckywin] 請教,我要用運放設計一個射極跟隨器,作為隔離電路，但要**需要的中心頻率21MHz，帶寬4MHz的信號不被濾掉，請問用什么放大器比較好啊
[答：Jing] You can use our Analog filter Wizard to for a BPF such as AD8027,AD8221 etc [2006-2-28 11:50:30]
[問：吉星] AD8067能否響應上升時間１０的鐘形脈沖．若不能請**一個型號．
[答：Troy] The AD8067 rise time is close to 10ns and has a slew rate of 650V/us. You should examine the AD8099 amplifier as well. Refer to the ADI website at www.analog.com.
[2006-2-28 11:50:45]
[問：yanmings] 請問在ADC前級的放大器放大線性度不好時應如何進行調節?
[答：Xiangquan] You"d better select a right amplifer, as it"s hard to compensate [2006-2-28 11:50:56]
[問：honghai_zhu] 基準電壓源 有哪些值得關注的指標?
[答：Jing] Initial accuracy, reference voltage and temperature drift is important. [2006-2-28 11:51:09]
[問：hanxin] 在選擇前端運放的時候,有個參數叫"擺率",什么樣的系統需要什么樣的擺率哪?比如AD7865前端使用模擬開關,在電力系統應用需要選擇運放的話,一般需要什么樣的擺率的運放?
[答：Mariah] The slew rate depends on the signal frequency and amplitude. [2006-2-28 11:52:08]
[問：jessiesong] what"s the most important parameter in choosing reference for ADC?
[答：Troy] It depends. Initial accuracy is usually important. So is drift over temperature. 16+ bit applications may require low noise. Portable applications need low supply current.
I find to many customers, the most important parameter is price! [2006-2-28 11:52:13]
[問：253760] 我需要ADC間隙性工作，因此也間隙性給時鐘，需要采集時才給時鐘，這樣是否有利于減少功耗，但這樣會帶來什么問題
[答：Jing] You can do that. But please pay attentation to the clock jitter and settling time . You should ensure the clock is stable for ADC, then you can sample the input signal. By the way, fast switching should also result some noise for your system. Thanks! [2006-2-28 11:53:09]
[問：zhouyl] 請問我用10bit的ADC芯片需要高精度的參考電源嗎？
[答：Mariah] You should calculate your system precision requirement and then select the suitable reference. [2006-2-28 11:53:21]
[問：吉星] 能否**高阻抗，低輸入電容，低噪聲的放大器．
[答：Troy] I recommend using resistors with less than 200 ohms. Larger resistors contribute more noise. Amplifiers with less than 12nV/root(Hz) noise are considered low noise. There are many low priced low noise amplifiers you can buy, such as the AD8691 and AD8667. [2006-2-28 11:55:36]
[問：callhxw] 請再加上ADC數據輸出穩定數據與分辨率及精度之間的定義區別？
[答：Rui] ADC的分辨率是指在不丟碼的情況下ADC能達到的**的Bit數
ADC的精度是指ADC的INL和DNL的誤差。 [2006-2-28 11:56:03]
[問：cola] 請問：基準電壓源對ＡＤＣ的精度的影響具體表現在哪里？
[答：Troy] The higher number of bits in the ADC, the greater the accuracy must be from the voltage reference. [2006-2-28 11:56:28]
[問：ecnanjing_EBY7E] 在微信號放大電路中,布線、印刷電路板的材質、焊接點、信號接入對整體性能的影響往往超過了放大器件本身的影響，請問**對以上影響，特別是部線有何高見？
[答：Mariah] You can send an email to china.support, then we can send some techinical material on the PCB layout for high precision circuit. [2006-2-28 11:57:18]
