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如何选择DAC

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[问：wangda
weidavid] 请问专家，如果所做系统要求数模转换的精度很高，而速度没有什么要求，那应选择哪种芯片比较合算，就是说可以达到要求，又比较省钱。谢谢
[答：Mariah] For high resolution and low speed DAC, you can consider sigma-delta DACs. This kind of DACs are also cheap.  [2003-10-30 10:47:58]
[问：hjldfp] 如何选择14位50MHz的A/D D/A芯片
[答：William] In general, the A/D, D/A selection is dependent on the type of end application you are working on.  For example, for communication, SFDR is important.  Please refer to the product datasheet and selection guide for details.  [2003-10-30 10:52:03]
[问：qiangnet] 能否简单介绍下目前D/A 转换器的工艺发展？失效模式？
[答：Albert] Failure modes related to DACs generally result from mis application of the device.
Usually overvoltage, breaking the absolute max ratings etc  [2003-10-30 10:52:59]
[问：davidlu] 应用于视频（1Vpp，PAL625--1249，NTSC525--1024）采集，10位或12位并行输出，如何选用数模转换器？谢谢。
[答：Wayne] I think you mean video decoder, not DAC. So, you can choose ADV7189, which support 10/20bit extended standard. However, if you just want to convert directly the CVBS signal to digital data, then you can use AD9203 which is 10bit 40MSPS ADC, or AD9200 which is 10bit and 20MSPS, AD9051 10bit 60MSPS.  [2003-10-30 10:53:17]
[问：aini8833
456.student] 数模转换器种类和特性是怎样划分的？
还有就是怎样和计算机相连？
[答：Mariah] The classification of DACs is according several criterions, such as speed, I/O types etc.
You can use the UART protocol of your MCU to communicate with PC.  [2003-10-30 10:53:59]
[问：samire] DAC的输出如何和平滑滤波器连接?对滤波器有何要求?如何进行设计这种滤波器?
[答：Mariah] You can find the filter design reference tools by the link below. http://www.analog.com/techSupport/designTools
/interactiveTools/filter/filter.html  [2003-10-30 10:59:25]
[问：john_ren] 1.选择转换器时，应当重点注意那些问题？在基本参数符合要求，我们一般重点考虑价格，请提供参考意见
2.在对转换的数据进行加密时，有那些常用芯片，常用什么算法？
3.转换器有无内置放大，即可以直接对模拟信号进行转换?
[答：William] 1) Cost is certainly very important.  However, the lowest system cost doesn"t always mean choosing the lowest cost component.  For example, higher performance product, even though it means higher component cost, can help reduce manufacturing cost (less adjustment, shorter development time, etc.)
2) The encryption is usually done at the FPGA/DSP behind the ADC.  There are many  algorithm available, depending on how much protection you need.
3) Many ADC"s have PGA built-in.  Please refer to the selection guide.  [2003-10-30 11:00:05]
[问：grey_
yz1949] 请问，目前最快的DAC芯片速度能达到多少M
[答：LiaoWS] The fastest DAC ADI can provide now is 500MHz. The part numbers are AD9782/4/6.  [2003-10-30 11:00:19]
[问：gecheng
liang] 产品在中国的销售代理和技术支持是哪几家公司？
高速处理芯片选型，开发需要哪些配套设备和开发软件？
国内有没有用AD高速处理芯片作过开发，能否提供技术支持？
购货周期一般是多长时间？
 
[答：William] We have 5 distributors in China.  Arrow, Avnet (Chinatronics), Future, GEHK/Excelpoint, and WPG.  There are many companies who have used our high speed ADC.  We have several experts who specialize in high speed ADC.  You can call our 800-810-1742 for technical support.  Typical delivery timeframe. is 4-6 weeks for our products.  [2003-10-30 11:04:13]
[问：vanbingo] 如何选用数模转换器的精度
[答：Mariah] You can find the accuracy specification in the datasheet. The accuracy selection of the parts is decided by your application.  [2003-10-30 11:05:44]
[问：john_ren] 1.如何实现转换电路与接口电路的电平兼容，常用那些方法？
2.当需要不同的采样率进行采样时，如何实现？
3.数字滤波如何工作的？当码流变换时如何适应，FIR滤波器可以解决这个问题吗？
[答：Wayne] 1. Normally you can use level translation like ADG3245/6/7.
2. Don"t understand your question, could you make it clear, or you can call 8008101742 later for discussion.
3. It"s a complicated question, however you can find a chapter in ADI book "Mixed-Signal and DSP design techniques". You can find the PDF file on www.analog.com by searching the words.  [2003-10-30 11:07:39]
[问：662135] 数模转换器的位数选择很重要吗？
[答：Mariah] Yes, it is the first important parameter when you select the part. It is decided by your application requirement.  [2003-10-30 11:07:47]
[问：guorock] SFDR是数字自由杂散动态范围，它是如何定义的？该指标对什么有影响？
[答：LiaoWS] You can find its definition from the datasheet of ADI DACs, AD9772 for example. It will influence the dynamic range of the system.  [2003-10-30 11:07:51]
[问：lichun
lei_1979] 现在最快的模数/数模转换器采样率是多少？
市场价格多少钱？
主要用于高速数据采集及重现。谢谢！
[答：William] One needs to consider also the resolution when talking about speed.  Also, the speed is highly dependent on the application.  For example, for communication, speed is in the order of hundreds of MHz.  But for instrumentation, the speed is only at a few MSPS.  Price also varies quite a bit from application to application because of different performance requirement.  [2003-10-30 11:08:54]
[问：izk] 如果DAC输入数据是高达200兆的LVDS的逻辑信号，ADI的产品有能满足该需求的解决方案吗？
[答：Wayne] We"re designing this kind of DACs, the part# should be AD972x, which is scheduled to release in 2004.  [2003-10-30 11:08:56]
[问：ShaoJunmei] 频率很高的情况下,如500M,A/D,D/A的选择,最应该注意是什么方面的问题?
[答：Albert] at 14 bit resolution, 400Msps ad9775
at 16 bit resolution, 400Msps ad9777
AD9723/24/25 will feature 600MSPS and are currently in definition.
All products supported by the analog devices High Speed Converter Group.  [2003-10-30 11:09:08]
[问：zddpy] 数据线与CPU控制器总线如何隔离最好。
[答：William] Typically, one needs to take care of the isolation of analog and digital lines with separate grounding and enough physical distance between the lines.  It is also dependent on the frequency of your bus and the signal.  [2003-10-30 11:10:50]
[问：ZHJNAME] 请问一下，能不能推荐常用的8，12位的DAC（较高的性价比，电压输出）？
[答：Mariah] 8bits:AD5300,AD5301,AD5330
10bits:AD5310,AD5311,AD5331
If you wants to get the product shor form. of ADI,you can call toll-free number 800-810-1742 to get it.  [2003-10-30 11:11:08]
[问：SUMMER
_CHEN] 如何降低DAC的噪声？对于时钟有何特殊要求？
[答：Albert] Precision DACs use architecture based around R-2R architectures and generally do not require a high frequency clock.

In high speed converters the clock is an integral part of the DAC and clock jitter,overshoot and undershoot on the clock signal contribute to noise.  [2003-10-30 11:12:45]
[问：wswtiger] 如何确保高分辨率高速（14bit 40MHz）的ADC的正确设计，
在数模转换器的选择中电流输出型和电压输出型的究竟应该怎样选择呢，他们的优点各是什么呢？
[答：Jing] You can accord to you design to select the correspond ADCs with relative INL,DNL and the interface . If you want to get more flexibility and high speed ,you can select the current output DAC. Of course ,you should add another amplifier after the current DAC to get the voltage output in needs.  [2003-10-30 11:14:43]
[问：shijh] 14.9MHz的DDS应与什么样的D／A最佳匹配？
[答：LiaoWS] ADI"s DDS integragtes DAC in it. You can use AD983X series of DDS.  [2003-10-30 11:14:48]
[问：SUMMER
_CHEN] 请问，通讯领域中采用的数字中频技术，会用到高速的DA器件，那么ADI在这方面有什么样的产品，有何特点？
 
[答：Wayne] It depends on what kind of communication system you"re doing, SW, or 3G. Basically you can choose TxDAC family like AD9786 (16bit, 400MSPS), AD977x, high level interpolation, and high sample rate is main feature. For integrated solution with ADC/DAC together we have MxFE family like AD986x (dual ADC + Dual DAC, high speed, and with some auxiliary ADC/DAC). We"ve also DDS AD983x, AD985x for your design.  [2003-10-30 11:15:31]
[问：hdwliang] 请问如何用DA实现4-20mA输出
 
[答：LiaoWS] ADI has such kind of parts: AD420 and AD421, both 16-bit accuracy.  [2003-10-30 11:15:46]
[问：tuolang2000] 现在的MCU中是不是有些已经内置了A/D,D/A转换？？？？
[答：Jing] Yes .Our ADuCXXX serial product such as ADuC812,ADuC814,ADuC831/2 and ADuC841/2 etc is such kind of MCU  [2003-10-30 11:16:12]
[问：ljp] DAC用作遥控,和MCU相连时,我该选择串行接口或并行接口?请专家给点建议.
[答：Mariah] Serial interface is used for small, low power applications.Parallel is used for fast update low overhead, and high channel count applications. [2003-10-30 11:16:19]
[问：kzw] 有什么型号的DAC，是四通道的，12位并行的，转换速度不低于500K?
[答：Jing] you can refer to our AD5340/1  [2003-10-30 11:16:42]
[问：QZDZ] 现在高速DAC数据输入主要采用什么样的传输模式及通讯协议,对数据传输方面有什么特殊的要求或在设计方面应该特别留意的地方.
[答：LiaoWS] Now the interface between microcontroller and DAC is mainly TTL/CMOS level, but later there will be LVDS interface. What you should take care is the layout, grounding and decoupling.  [2003-10-30 11:17:25]
[问：kzw] AD公司的芯片精度比较高，这是大家公认的，但有一点不太好，就是太容易被烧掉了，我想问一下是为什么？难道是精度高就易坏吗？另外，芯片坏了一般不怎么发热，总是烧了还不知道，烧了后并不是不能工作，而是性能变坏，比如说，转换速度变慢。
[答：William] I don"t believe our product is more easy to damage.  It is, however, generally true that a "mixed signal" product is more sensitive to ESD damage (than purely digital or analog).  It is simply because when one combines both analog and digital technologies onto the same IC, the process becomes less robust to ESD.  What you describes is a bit strange, I"m curious if it was because the product was purchased from "electronic market" where the quality is often not stable.  [2003-10-30 11:17:42]
[问：riple] 如何正确选择数模转换器:转换速率和带宽应如何取舍？
[答：MelConway] Conversion speed [settling time] and bandwidth specifications depend greatly on the DAC architecture.
Bandwidth can either be
1] multiplying bandwidth which is the maximum frequency that can be applied to the Reference input or
2] waveform. generation bandwidth which is related to the DAC digital input update rate, which depends on the interface type, and conversion speed. This bandwidth also depends on the SFDR Spurious Free Dynamic Range or THD Total Harmonic Distortion which give a measure of the quality of the output at certain frequencies.

The highest bandwitdth is always obtained from Current Output DACs which have no input/reference buffers or output buffers to add delays to the signal processing. Of course parallel interface DACs update faster and are therefore more suitable for higher bandwidths.

Everything depends on the actual frequencies that are to be used, and whether the application is processing a signal input or generating a signal output.
Use Voltage output DACs upto approx 100kHz, and Current output above this.
Parallel interface allows an update rate of upto 50MHz, while Serial interface allows update rate upto approx 3MHz.
Example the AD5443 has a multiplying bandwidth of 10MHz+ but an update rate of only approx 3MHz as it is Serial interface. The AD5445 with Parallel interface can update upto 50MHz but the settling time limits the usable bandwidth to approx 10MHz.
Please contact our Applications Engineers with more details of the application for a selection of suitable parts.  [2003-10-30 11:18:16]
[问：wffae] 请问，要达到高精度，对 reference voltage 要求一定很高吗？
[答：LiaoWS] The voltage reference"s accuracy influence the accuracy of the part. So for high performance DAC, it needs high performance reference.  [2003-10-30 11:19:41]
[问：yoursdd] 如果对视频信号进行数模/模数转换该如何选择转换器，它的关键性规格是哪几个方面呢？谢谢！
[答：Wayne] If you want to decode CVBS or Y/C signal to YUV digital data, then you can use video decoder like ADV7189, ADV7183A. And for encoder, you can use ADV717x (SDTV), ADV719x (some support progressive scan video), ADV73xx (support HDTV). ADI advantage is high oversample rate, high SNR, noise figure.
If you want to convert RGB from digital to analog RGB, then ADV7123/7/8 is choices.
If you want to convert CVBS directly to digital data by time, then general purpose ADC like AD9203, AD9200, AD9051 as 10bit resolution. You can also use AD922x as 12bit solution.  [2003-10-30 11:21:17]
[问：qin] 多通道的DAC的通道匹配性能如何保证?
[答：Theresa] DAC- to-DAC crosstalk is defined as the glitch impulse that appears at the output of one DAC output due to both the digital change and subsequent analog O/P change at another DAC. The victim channel is loaded with midscale
and DAC-to-DAC crosstalk is specified in nV-s.  [2003-10-30 11:22:51]
[问：wffae] 请问贵公司的D/A一致性如何？我曾用过台湾多家D/A但产品的一致性差，在同样条件和环境下，输出的摸拟电压值有差异，不得不对每个产品作补偿调整。
[答：William] The specifications are guaranteed in the datasheet.  You can refer to the DC performance (such as offset and gain error) for further details.  [2003-10-30 11:23:44]
[问：qin] 请介绍电源对高速DAC的噪音影响.是否需要用线性调整器而不用开关电源?如果用开关电源,对它的波纹如何进行处理?
[答：LiaoWS] For analog circuits, linear power supply is required. But switched power supply can be used if you can filter it well. If you want to filter the ripples in the power supply, your weapons are capacitors, inductors. For more details, send mail to china.support@analog.com, please.  [2003-10-30 11:23:57]
[问：qinqingzi] 1MSPS的转换率，如果由外部提供时钟，会不会有不稳定之类的问题
[答：Jing] General Crystal Oscillator can generate up to 30MHz frequency. You can use a external clock and be aware to the filter circuit and the stability of the voltage reference source.  [2003-10-30 11:24:30]
[问：lwbence] DAC的一些相关指标在各个领域的应用中有没有一些标准，比如在通信领域的要求或是其它领域
[答：LiaoWS] The specifications for the DAC is different from application to application. For communication systems, the requirement is the SNR, SFDR, etc. Which are mainly frequency domain specs.  [2003-10-30 11:25:30]
[问：ljp] 如果8位DAC没有串行口,如何和串口的MCU相连接?是否要加串并转换?对这转换有何要求?
[答：Mariah] If the MCU has parallel port, you can connect the DAC to MCU directly. If you just wants to use serial port, you should convert parallel to serial. You should pay attention to the level consistency of the conversion.  [2003-10-30 11:26:58]
[问：wwenguang] DA的一个参数:MSPS UPDATE RATE是什么意思,是不是最高的工作频率?
[答：LiaoWS] MSPS is million samples per second
Update rate is MSPS for many converters,e xcept the Sigma-Delta ones. They are not maximum working frquency, they are the frequency that converter can work normally. The maximum should be faster than them.  [2003-10-30 11:27:01]
[问：hua_xing_jiang] 请推荐几种用于通讯的转换器芯片。谢谢。
[答：LiaoWS] In whihc kind of wireless system?
For 3G, we have AD6644/5, AD6623/4, AD6634/6, AD6650/2, AD9777, AD9786 and so on.

For details, contact 800 810 1742, please.  [2003-10-30 11:28:06]
[问：kenvert.lee] 刚才提到DAC的失效模式，请问，通常有哪些设计上的不当会导致DAC失效？DAC最容易损坏的是哪一部分？谢谢！
[答：Albert] Designs that cannot tolerate failure include mission critical applications, in medical, military etc.
Dacs sections prone to failure include:
(a) the power supply pins due to overvoltage from high voltage spikes  on the power supply generated fron inductive switching in the system etc.
(b)Interface lines again due to overvoltage.
(c)Output amplifier due to ESD and overvoltage

All failure modes are generally attributed to mis application of the device. Generally when the devices are very robust when operated within their absolute max ratings.  [2003-10-30 11:28:22]
[问：chenpld] 在视频信号的DAC选择上，为达到广播级的质量，有什么要注意的？
谢谢！
[答：Wayne] Basically you need to follow broadcasting standards locally. At first, you need enough oversample rate, then SNR to reach one of the requirements. ADV719x can be good choice. ADV73xx is new coming family which has 108MSPS or even 216MSPS sample rate. ADI has some other properity technology in video, like DNR, SSAF filter, which help to reach the requirement.  [2003-10-30 11:29:23]
[问：ljp] 5. 串行DAC的时序控制较麻烦,和微控制器的I/O通信时间较长,除了改用并行DAC,还有什么好办法?
[答：LiaoWS] For serial interface, few wires will be needed. It is suitable for multi-channel applications. For high speed DACs, most of them are parallel interface.  [2003-10-30 11:29:54]
[问：zbchen69] 如何考虑DNL 和INL 对转换精度的影响问题？在选择相关芯片时应如何考虑？
[答：William] DNL and INL represent the linearity of the conversion.  Depending on your application, you need to decide how much error you can allow in the code from the ideal value.  [2003-10-30 11:31:04]
[问：421956] 请问：用于直流伺服电机控制的DAC在精度与速度上一般选用什么类型的DAC比较好，是电压输出的，还是电流输出型的！
[答：Albert] Again DAC selection is highly dependant on the system and its requirements which will determine the accuracy and speed of the DAC.
Generally voltage output DACs are a more complete solution. Iout DACs generally can only supply 2mA max and require an external amplifier for current to voltage conversion.  [2003-10-30 11:32:37]
[问：wyhljb] 在数模转换中，中间所经过的途径与通信中的数字信号和摸仪信号是同样的吗？？
  转换中的干扰有那些要注意的？？？
[答：Mariah] I am not sure about the "approach" meaning? If you wants to get more help, please call toll-free number 800-810-1742.  [2003-10-30 11:32:54]
[问：qin] 如果降低温度对DAC性能的影响?或者提高温度使用范围?
[答：William] Many DAC"s come with a reference input.  The temperature performance can be usually enhanced by using an external, low tempco reference to extend the temperature range of the DAC.  Note that all semiconductor products have temperature grade.  One should not use a product beyond the range.  [2003-10-30 11:33:13]
[问：ljp] ADI公司有没有ADC和DAC在同一封装里的产品?
[答：Wayne] For precison solution, Microconvertor series like ADuC81x/2x/3x/4x is good choice which integrate ADC (12/16/24 bit, 200KSPS....), 8051 MCU and 12bit DACs or PWM output in one chip.
For high speed solution, you can find MxFE family including AD986x, AD987x which has broad applications in STB, modem, communication systems.  [2003-10-30 11:33:44]
[问：qiangnet] 能否推荐一个10M/8bit输出的D/A转换器？此外，深圳ADI的D/A转换器的负责人怎样联系？thanks!
[答：Jing] You can refer to our AD5224,AD5225 and AD5226.You can contact with our Shenzhen representation at 0755-83783430(Mr.Zhang Xinming).  [2003-10-30 11:34:42]
[问：samire] 单电源和双电源的DAC在性能有何区别?
[答：MelConway] Unipolar = single supply compared to Bipolar = dual supply DACs:

Unipolar is cheaper and simpler [only 1 power supply], and is suitable for battery powered equipment. It is typically lower power [as it uses only half the supplies of a bipolar DAC].
However the signal has no ground [unless you setup a pseudo ground, which is not optimal] which makes it unsuitable for AC and control [+/-] type applications. The voltage swing on the output is typically less than half that of a bipolar output which reduces the dynamic range, Signal to Noise Ratio, and the size of the Least Significant Bit LSB which makes it unsuitable for high precision, high accuracy applications. As the IC Integrated Circuit has to withstand much lower voltages, the feature size can be reduced, reducing the die size and therefore cost.
Bipolar DACs are necessary for AC, control and any high precision or high accuracy applications whre performance is important. Modern voltage doubler and inverter ICs [based on charge pumps etc.] can generate the necessary negative and high voltages for bipolar DACs at very little cost whilst maintaining all the performance advantages.
Depending on the application a very rough split would be to use unipolar DACs at 12bits and below, and bipolar DACs at 12bits and above, however everything depends on the actual application.
Please conatct our Application Engineers who will be happy to explain further and make part recommendations.  [2003-10-30 11:34:47]
[问：stick] 能否解释一下DAC中INL，DNL，SFDR等指标
[答：LiaoWS] Please find them from page 15 of the presentation. Also, you can find their specification from our datasheets. For details, please send mail to china.support@analog.com, they will be happy to help you.  [2003-10-30 11:35:23]
[问：snailman] 请问，在精度要求很高的场合，在模数转换器的参考源选择及外围电路的设计上有哪些需要考虑的因素呢？比如是选用转换器自身提供的参考源好呢还是使用外部参考源好呢？谢谢
[答：William] One needs to use a high performance power supply and reference.  Both the power supply and reference should be decoupled to a quiet analog ground with two decoupling capacitors (one for high speed noise and one for voltage stability).  External reference typically provides a better performance.  [2003-10-30 11:36:15]
[问：liuhuaker] 主持人你好，请问DAC的转换速度是通过哪个参数体现的。
[答：LiaoWS] you can find their MSPS, settling time. For low speed DACs, it is important to know its settling time.  [2003-10-30 11:36:21]
[问：WANGGYU] 96khz音频输出可以选择贵公司的那种类型的DAC，请教国内常用的供货稳定的一种
[答：William] Our AD1853, AD1955, etc. can support 96kHz.  In fact, AD1955 is one of the best audio DAC available on the market.  [2003-10-30 11:38:41]
[问：wffae] D/A输出电压会受负载的变化而受到影响吗？
[答：Mariah] The output will be influence by the load. If you drive a heavy load, you should add a buffer at the output of the DAC.  [2003-10-30 11:39:08]
[问：lijianhong] 怎样配置一个D/A电路，使输出为双极性电流？
[答：LiaoWS] For bipolar voltage output, you have to select the right kind of DAC. Another way is to use the bipolar amplifiers to implement the current to voltage conversion.  [2003-10-30 11:39:11]
[问：nilibi] 请问时钟抖动对DAC的影响有多大，有没有公式，谢谢
[答：Theresa] Jitter causes a voltage error which is a function of slew rate and results in an overall degradation of SNR.
Theoretical SNR =6N +1.76dB
where N="resolution"
  [2003-10-30 11:40:13]
[问：jikjikjik] 有那些接口形式可选择?
[答：Mariah] Basicly, SPI, I2C for serial port and parallel port.  [2003-10-30 11:40:45]
[问：jikjikjik] 请问常用的关于声卡使用的DAC/ADC产品有那些?价格如何/谢谢
[答：William] We have a family of SoundMax AC97 codec (such as the AD1885).  If you are looking for general purpose codec, then our AD73311 or AD73322 are suitable.  [2003-10-30 11:41:13]
[问：wffae] D/A芯片的复位是什么意思？D/A芯片会复位吗？
[答：LiaoWS] It means that when power on, a fixed lotage level will be set. The reset for the DAC is useful for some applicaitons.  [2003-10-30 11:41:52]
[问：huhuizhu] What specification of DAC can presents the difference of settle time from a voltage level to another one on different voltage level?
[答：MelConway] This is a combination of Settling Time and Slew Rate. Settling time gives the time for the output to stabilize given a certain [specified] step size [typically full scale]. Settling time can range from 2-100us for Voltage output DACs to 30-500ns for Current output DACs. Slew rate is the maximum rate of change of the output - example 5V/us means that the output can change a total of 5V in 1 microsecond [us]. If the output was at 1V it could move to 3.5V [a change of 2.5V] in 0.5us.  [2003-10-30 11:42:37]
[问：QZDZ] 请介绍一下,现在DAC在虚拟仪器方面的应用情况
[答：Wayne] Most application of DAC in virtue instrument should be multi-channel DACs. So, AD53xx, AD54xx, AD55xx are big family for your choices. For exmaple, AD5380 can reach 40 channels 14bit. While, AD5391 is 16 channels 12 bit DAC, AD5392 is 8 channels 16 bit DAC.  [2003-10-30 11:43:07]
[问：peng-kai] 在DAC与放大器一起构成程序控制放大器时，除了精度位数以外，我应当还考虑写什麽技术指标。谢谢
[答：William] The DC specifications are important in this application.  One should look at offset, gain error, drift (if temperature is important), etc.  [2003-10-30 11:43:58]
[问：wffae] 请问贵公司有集成温度补偿的D/A芯片吗？通常能保证的温度范围是多少？ thanks!!
[答：LiaoWS] We have not this kind of DACs. We can insure our temperature range from 0-70 degree to the military standard.  [2003-10-30 11:44:16]
[问：jikjikjik] 请问那一类DAC适合做比精度较高的仪表器件?
 
[答：Theresa] The most suitable DACs for high precision instrumentation are generally DACs with greater than 12 bits resolution, 16 bits resolution is best choice.

Bipolar dacs or Iout Dacs may be good options depending on the customer requirements.  [2003-10-30 11:44:35]
[问：lwbence] 如果要想达到20bit以上的精度，对电源的要求如何（如果不考虑外部噪声，只考虑电源引入的），是不是只能用电池供电
[答：Jing] We can provide 16 bit resolution DAC such as AD5543 and AD5544 now. You can use the battery or other power supply.But you should pay more attention to the decoupling circuit and the stability of the reference .Thanks!  [2003-10-30 11:44:47]
[问：de88] 选择转换器时,在EMC方面应注意哪些问题.
[答：Gary] A lot of EMC compatibilty is based on system design and not just component selection.

PCB Grounding, Layout and decoupling of power supplies have a big effect on Succeptability and Emissions. System shielding also has a big impact on this. There are a lot of articles written on design techniques to minimise EMC. please read the following article for more information.