• 仪器分析，红外、核磁、紫外 红外吸收光谱法;(IR) Infrared Spectroscopy (6) 核磁共振波谱法; (NMR) Nuclear Magnetic Resonance Spectroscopy (6) 紫外可见吸收光谱法 (UV) Ultraviolet Spectroscopy (4) 质谱法；...
• 新品动态】据天美分析仪器讯，天美分析仪器研发中心(TREC)新推出高灵敏度积分球IS-2600。IS-2600的设计是为了更好地与天美高端科学研究级紫外可见分光光度计UV2600组合应用，两者的完美融合，极致展现了分光光度计的...


【仪器仪表网  新品动态】据天美分析仪器讯，天美分析仪器研发中心(TREC)新推出高灵敏度积分球IS-2600。IS-2600的设计是为了更好地与天美高端科学研究级紫外可见分光光度计UV2600组合应用，两者的完美融合，极致展现了分光光度计的出色性能指标。

IS-2600积分球全面采用国内外更新的研发技术，性能指标媲美同类进口积分球产品，具体技术特点如下所示：
●直径60mm的积分球，内衬为光学级改良版聚四氟乙烯材料，漫反射比大于99%
●高反射和高准确度，拥有极小开口率
●0°/8°入射角和具有S/R转换功能的主机相结合
●无需特殊附件，即可实现漫反射和全反射测定
●同时满足液体和固体的透过率测定
IS-2600积分球应用于天美UV2600之上，进行一系列的测评实验，呈现出令人意想不到的完美结果：

总结：天美UV2600的60mm积分球IS-2600拥有超低开口率、超高反射率，整体性能指标较高，甚至超过很多进口厂家指标。
IS-2600积分球与UV2600完美融合，更为有助于应用于化学工业，食品安全检测，医疗卫生，水质分析，生态环境保护，生命科学研究等各行各业的科学研究及生产制造工作。


展开全文
• 介绍了一种基于UV（紫外）法的高温抽取式FFT（快速傅里叶变换）氨逃逸在线监测系统，分析了该系统在SCR脱硝工艺高温、高尘等复杂环境中的应用效果及特点。结果表明：该仪器重复性为0.69%，相关系数为0.999 2，采样...
• 根据UV灯的光强能量值判断与反射罩好坏的关系，需要使用光学仪器UV能量计来检测。 UV灯固化设备 一、UV灯能量的测量 测量UV灯的能量，主要有两种方式： 1.UV灯辐射能量的峰值，单位是mW/cm2 (毫瓦/平方公分)，...
  UV灯的效率，必须由灯和反射罩的状态来综合评价。如果是新灯管，但反射罩已老化，这灯的效率也好不起来；老灯管配上新灯罩，效率也一样不会好。根据UV灯的光强能量值判断与反射罩好坏的关系，需要使用光学仪器UV能量计来检测。

UV灯固化设备
  一、UV灯能量的测量

测量UV灯的能量，主要有两种方式：

1.UV灯辐射能量的峰值，单位是mW/cm2 (毫瓦/平方公分)，这与灯的瓦数与反射罩好坏直接有关。

2.UV灯在一定时间内, 在照射面上所接受的UV能量, 单位是mj/cm2 (毫焦耳/平方公分), 这与灯的能量强度，照射距离，照射时间有直接关系。

二、测量UV灯能量的仪器/工具

1.UV能量计

好的UV能量计，可测量及显示以下数值：

a. UV峰值输出光强：mW/cm2；

b. 一定距离与照射时间下所接受的UV能量：mj/cm2；

c. UV灯不同波段(UV-A, UV-B, UV-C, UV-V) 的能量值: mW/cm2 + mj/cm2；

uv能量计
  三、UV能量辐照记录仪

1.可以同时检测紫外光源光强和能量值（显示屏直接显示数据）。

2.可以同时测试四个波段范围(UVA, UVB, UVC, UVV)。

3.可直接查看光强能量数据曲线图。

4.可连接电脑软件导出数据图表可保存JPG,ING格式图片，Word文档和Excel表格。如下次需要进行数据分析还可随时导入表格。

UV能量辐照记录仪
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• 属高精度运放,而TI(德州仪器)的定义则是要低于0.5mV(即500uV)才算是高精 所谓高精密度是指OPA输出结果（电压信号）的精准度，一般是以偏移电压（Vos，os＝Offset）为判定基准，NS（美国国家半导体）的定义是低于...
所谓高精密度是指OPA输出结果(电压信号)的精准度,一般是以偏移电压(Vos,os=...属高精度运放,而TI(德州仪器)的定义则是要低于0.5mV(即500uV)才算是高精

所谓高精密度是指OPA输出结果（电压信号）的精准度，一般是以偏移电压（Vos，os＝Offset）为判定基准，NS（美国国家半导体）的定义是低于（以下皆含等于）1mV（毫伏）即属高精度运放，而TI（德州仪器）的定义则是要低于0.5mV（即500uV）才算是高精度OPA，不过定义方向一致，只有程度之别罢了.高精度方面是以Vos为基准参数而定的。
高精度运算放大器的特点 高精度运放解决了科学和工业测量应用领域中放大低电平模拟信号的难题。
因为测试测量等应用推进了高精度运放的发展,这类产品由于对信号精准度的要求极高,如果将这类运放整合到后端芯片中开成SoC，其它电路的噪声将严重干扰此类运放的正常运作，因此就现阶段的技术来看，这类运放将是最不容易被整合的组件。
针对特殊应用的附加特性，以及极小的封装和低电源电流，多种需求为制造精密运放带来挑战,与输出精度相关的因素还有温度漂移时的输出变化,以及供电抑制比,共模抑制比。
CF725高精度运算放器的特点介绍: (1)低的输入噪声电流；
（2）高的开环电压增益； （3）低的输入失调电流； （4）低的输入电压漂移； （5）高的共模抑制比 （6）该器件有两种工作温度范围；
中广芯源专业电源方案，运算放大器，马达驱动，大功率MOS 等系统服务商，小家电电源方案，工业辅助电源方案，智能LED调光电源驱动IC,功率:30W以内,有针对性的方案提供产品特色降低系统成本，提高设计灵活性。 12V降压5V  2A SOT23-6小封装同步降压IC  12V降压5V 3A小封装大大电流DC-DC升压 升压解决方案： 5-35V输入升压8-100V各种升压解决方案 大功率300W 40-80V输入升压45-300V升压解决方案
降压解决方案： 8-80V降压5V 1A 12V 500MA 高压降压 15-100V降压12V 2A 5V 1A 大功率高压降压降压方案
另外本公司提供各种DC-DC晶圆颗粒，协助客户封装生产。
M*P1484 dc-dc晶圆 1482电源IC晶圆 A*P2576 2596晶圆 431基准源芯片晶圆 A*P4310晶圆 A*P2952晶圆 4329晶圆 1117晶圆 升压IC晶圆 降压IC晶圆 432晶圆 各种DC-DC晶圆
1 220V降压12V/24V输出功率更大以适应更高功率的应用 2 非隔离电路无需变压器，外围电路更简单 3 节约外围元件成本 4 完全集成的缓启动电路降低了器件的应力及输出电压过冲 5 外部电路实现精确的限流编程 6 更宽的占空比实现更高的输出功率，同时可以使用更小尺寸的输入滤波电容 7 输入欠压(UV)检测可以防止关机时输出的不良波动 8 输入过压(OV)关断电路提高了对输入浪涌的耐受力 9 具有输出短路保护，开路保护功能
MC34119 小功率音频放大器  NE592 视频放大器OP07-CP精密运算放大器 TI[DATA] OP07-DP 精密运算放大器 TI[  NE5532 高速低噪声双运算放大器 TI   双运放 NE5534 高速低噪声单运算放大器 TI   单运放 OPA602  高速高精度运放（无OPA2602） OPA604单  OPA2604双   低噪声运放  OPA132单  OPA2132双  OPA4132四  高速低噪运放  OPA227 OPA2227 OPA4227  OPA228 OPA2228 OPA4228 高精度低噪声运放  AD844：60MHz、2000V/us单芯片运算放大器 高带宽、非常快速的大信号响应特性   常用的压控放大器：AD603  VCA810  VCA820 AD603：低噪声 电压控制增益运放 90MHz带宽 VCA810：35MHz高增益可调节范围宽带压控放大器   25mV/dB(-40dB~40dB)  VCA820：150MHz增益可调运放(-20~+20dB)
OK122   带宽150KHZ 低噪声运放 OK222   带宽1MHZ 低噪声 低静态电流 OK358   带宽1MHZ双运放 OK324  带宽1MHZ 四通道运放 OK522  带宽3.6MHZ   低噪声双运放  OK622  带宽6.5MHZ 低噪声运放 OK722  带宽 10MHZ  低噪声双运放 OK6041  6042低静态功耗 单通道和双通道运放 OK8051  8052 带宽250MHZ 高速运放 单双通道 OK8551  8552 8554 高精密 零温漂 单通道 双通道运放
温度测量 压力传感器 精密电流传感 电子秤 应变计放大器 医疗仪器 热电偶放大器 手持式测试设备
中广芯源 姜楠    手机：134 2429 7678   QQ：1004509729     罗生    手机：134 2514 6336   QQ: 2805981750
高精度运算放大器的应用 高精度运算放大器的运用范畴很广，在产业领域中可用于量测仪器、控制系统、HAVC（Heating, Ventilating, and Air Conditioning，加热、通风、空调）、程序控制、资料撷取系统、ATE（Automatic Test Equipment，自动测试设备）等。在医疗领域中也有超音波、气体分析、血压计、诊断器、医疗影像系统等，此外汽车中的引擎管理、传动系统管理，或实验室内的测度计等，都需要运用上高精度的运算放大器。高精度运算放大器主要面向测试与测量仪表、汽车电子系统及工业控制系统产品市场。
四类主流运算放大器的发展趋势及其应用热点 高速、低电压/低功耗、高精度三类运算放大器的市场预计在未来的五年会稳步增长，年复合增长率分别达到13%、8%及11%，通用运算放大器的年复合增长率预计为5%。从应用的角度讲，不同的系统对运放有不同要求，选择合适的运放对于系统设计至关重要。对于通信、高速测量仪表及超声波设备等高速应用，交流特性极为重要。但对于低速的高精度系统，直流方面的特性则通常更为重要。衡量系统在交流特性方面的参数有信号带宽、失真率、噪声等；而衡量系统在直流特性方面的参数有输入补偿电压、开环增益、输入偏置电流及共模抑制比等。 
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• 分析了太阳紫外辐射光谱特点及漫透射板在轨工作的紫外辐照剂量，利用标准氘灯作为光源模拟太阳115~200 nm的紫外光谱，在特定距离下对紫外熔石英漫透射板进行了辐照实验。太阳等效紫外辐照48 h后，熔石英漫透射板半球...
• 仪器仪表用Σ ΔADC产品 在线问答: [问：ljsword] If my 10bit adc is only 6bit at test, what is main reasons? [答：Adrian] It could be due to poor power-supply decoupling or poor grounding on the PCB...
仪器仪表用Σ ΔADC产品
在线问答:
[问：ljsword] If my 10bit adc is only 6bit at test, what is main reasons?
[答：Adrian] It could be due to poor power-supply decoupling or poor grounding
on the PCB layout.
The power supply should be decoupled with the recommended capacitors close to
If there are seperate DGnd and AGnd then the datasheet should be checked for t
he recommended method of connecting the grounds.
Care should be taken in layout of the PCB to keep digital signals away from an
alog signals.  [2003-8-5 10:52:26]
824 can get the same effect as the single sigma-delta ADCs.  [2003-8-5 10:52:5
1]
后数字滤波器设计原理方面的详细一些的资料，本人非常感谢！
ntact our technical support center
China Support Center free Call Number: 800 810 1742
ADI analog products China Support Center Email: China.support@analog.com [2003
-8-5 10:52:55]
度？
[答：Wayne] If you want to know the property of Sigma Delta ADC, you need firs
t to understand 4 basic concepts: Oversampling; Noise Shaping; Digital Filteri
ng; Decimation.
Basically Sigma Delta ADC"s conversion rate is slower than SAR ADC or parallel
ADC, and the it"s mostly at or under KHZ level. However, we"ve some part like
AD7738 which can reach 15KHz. [2003-8-5 10:52:56]
[答：WenShuai] It is the ouput rate.  [2003-8-5 10:54:45]
[答：Eagle] 一般，芯片线性度足够做三相电表。如果你有更高要求，请直接联系技术支
持中心。
China Support Center free Call Number: 800 810 1742 China.support@analog.com [
2003-8-5 10:56:32]
[问：breeze73] 请问差分输入的转换结果是怎么输出的？是分时输出的吗？
[答：WenShuai] No, it is output like a single input.  [2003-8-5 10:56:55]
[答：Grainne] Don"t understand the question exactly.
The AD7730 first stage filter is sin3 filter. It has short settling time - 3 x
conversion time = 3 x 1/data rate. The second stage filter provides more filt
ering, lower noise, possibly 50/60Hz rejection, but longer settling time. The
AD7730 noise is specified only for the full (second stage) filter. To have som
e idea about noise with only first stage filter, look into the AD7731 datashee
Michal. [2003-8-5 10:57:29]
[问：lxq00008] 请问怎样选择高精度a/dc的外围元件,a/d转换后数据处理我要使用正切表
查询,我怎样能在最小数据位数下取得0.1度的分辨率?
[答：William] Typically you can calculate the SNR of the external components t
o ensure the accuracy requirement of the ADC can be met.  I"m not sure what yo
r information on accuracy calculation.  [2003-8-5 10:57:37]
[问：qdayan] Do Σ-ΔADC converters have any shortcomings compared with other
Thanks a lot.
[答：Adrian] S-D ADC converters have a number of benefits, including very high
-resolution, low-noise, simple anti-aliasing filter requirements, programmable
They are generally slower than other ADCs, so for very high sampling rates a S
AR or FLASH ADC may be required.
The ADCs discussed in todays seminar offer 16-bit to 24-bit resolution, at spe
eds up approx 10khz. There are faster sigma-delta ADCs available from Analog D
evices, for example for Audio appications, but for the highest speed a differe
nt ADC architecture is needed.  [2003-8-5 10:58:13]
[问：renmacro] 请问一下：1.过采样时钟是内部产生，还是需要外部提供？
2.过采样倍数通常有多大？可编程吗？设计时怎么考虑这个问题？
[答：WenShuai] It should be provided by the external clock.
The oversampling rate is in the chip, cannot be programmed.  [2003-8-5 10:58:2
8]
[问：liberal2002] Sigma-Delta转换器的精度是否可以根据需要动态调整？
[答：Mariah] You can adjust it by yourself.  [2003-8-5 10:58:52]
换输出不应该有这么大的偏差,是否器件有问题呀?
[答：WenShuai] Which part you are asking now?  [2003-8-5 10:59:25]
[问：xingge] 怎样能够解决小信号的干扰问题？
[答：Wayne] First is the choosing of devices with high performance (low offset
, low bias current, low noise...), especially for front end devices like ampli
fier, or high precision ADC with good front end performance (like chopper amp,
PGA, temperature compensation circuit, which are mostly integrated in some AD
I Sigma Delta ADC like AD7719, 7709, 7708, 7718). Another example, for groundi
ng noise, you can choose instrument amplifier like AD620/3, AD8221 which can g
reatly reduce those kind of interference.
Second is PCB layout, especially grounding. You can find many books on this to
pics. ADI has some PDF books on this as well, such as:
http://www.analog.com/technology/
amplifiersLinear/training/sensorSignal.html
Also, you need use other manners like shielding, especially for noisy environm
ent.  [2003-8-5 11:00:02]
[问：ljp] 如何解决电源50Hz的干扰?采用带阻滤波方法能行吗?
[答：William] Many of our sigma-delta ADC filter out the 50Hz (and 60Hz) inter
nally using digital band stop filter.  Furthermore, you can use differential s
ignals to ensure the interference can be rejected by common mode rejection.  [
2003-8-5 11:00:30]
[答：WenShuai] Yes. If the part said it can be used in undersampling mode. For
[问：liberal2002] 请告知1阶Sigma-Delta A/D转换器基本结构
5 11:02:21]
[问：猫王] 我把一次实验的结果描述一下:测试一下它的线性度,实验时候这么处理:用通
02:28]
[问：wzy006] 该类产品一般采样速率都较低，不知目前16位的最快可以是多少？
[答：Grainne] In the instrumentation product line here at ADI our faster speed
is 8.5KHz at true 16 bit peak to peak resolution. (AD7738)
However there are also products from ADI such as the AD772x family that reach
speeds of hundreds of KHz and these are also sigma delta architecture.
Check out the web to look at datasheets on these products.
Grainne  [2003-8-5 11:03:20]
[问：qin] 对传感器的非线性如何进行补偿和校正?
[答：WenShuai] It will be decided by which kind of sensors you are using. For
example, 4-arm bridge has the linear property, but one arm bridge doesn"t have
it.  [2003-8-5 11:03:35]
[答：Mariah] You can do self-calibration and system calibration according to t
he datasheet.  [2003-8-5 11:04:29]
[问：xingge] 如果要把1mv的电压转换成1mA的电流，不加另外的转换电路能行吗？如果可
以，怎样解决？选择那些芯片较好？
[答：Eagle] 用OP1177构建恒流源电路，或电压到电流转换电路，或用仪表放大放大，用
原因?见过类似的问题吗?请指点,谢谢!
[答：William] From what you described, this is caused by offset error and gain
error.  What you need to do is to record the min and max values and then simp
ly re-calculate the step size.  You can contact our technical center for furth
er assistance on how to calculate this.  [2003-8-5 11:05:01]
而当输入直流信号时输出会有很大的波动？
[答：WenShuai] Maybe this is because of your grounding and power supply. Any f
urther technical support needed, please mail to china.support@analog.com or ca
ll the toll-free number 800 810 1742  [2003-8-5 11:06:31]
[答：William] In principle, sigma-delta ADC is no different to others.  It"s m
ainly higher resolution, lower speed.  It is mostly useful for instrumentation
and other low speed application.  [2003-8-5 11:06:50]
[答：WenShuai] What does 空闲噪音 mean?  [2003-8-5 11:07:04]
AN-388: Using Sigma-Delta Converters-Part 1
AN-389: Using Sigma-Delta Converters-Part 2

You can find them in ADI website.  [2003-8-5 11:07:29]
[答：Adrian] The PGA improves the ADC resolution, in terms of uV or nV.

For example, the AD7719 has an RMS noise of 2.3uV on PGA=1 at a 20Hz conversio
n speed, which equals 21 effective-bits resolution.
With PGA=8 the RMS noise is 0.65uV, which equals 19.5 effective bits resolutio
n.

Therefore the PGA allows a more accurate measurement over a small input signal
range.

On some S-D ADCs, at higher speeds, the resolution is limited by quantisation
noise rather than thermal noise, so there is a bigger improvement in resolutio
n when you use higher PGA setting. [2003-8-5 11:08:03]

[答：William] 24-bit are the most common.  Higher number of bits would mean sl
ower response time so even it is perfectly possible to achieve higher number o
f bits, most Sigma-delta ADC would stop at 24 bits.  There are also system noi
se issue needs to be considered.  [2003-8-5 11:08:17]
吗?(用电流法,无额外IC)
[答：Eagle] 还要看RTD精度。  [2003-8-5 11:10:02]
[问：ljsword] how to measue the inl,dnl of the adc?
[答：Grainne] The INL is deviation from an ideal straight line in graph of out
put code versus input voltage.
We use ultra high precition voltage source in our testers to check the INL.
The DNL is deviation in 1LSB size. This would be hard to measure, because the
sigma-delta ADC are inherently 24-bit accurate and would be hard to even find
a measuremnt system acurate enough to check it.
Michal.  [2003-8-5 11:10:45]
[问：yjems] 我需要测量微伏级的信号，为了获得比较大的（1-100）可变增益范围，我想
。
种影响呢？
[答：Wayne] It"s better not to put digipot on front analog end, which may infl
uence a little the performance because of its temperature drift, digital inter
ference. If you had to use this way, you need to make sure your layout is stri
ctly following up related rules then digital signal will not influence small a
nalog signal. You need to set up some compensation manner (at digital processi
ng, for example).
By the way, we"ve instrument amplifier AD8221 which has better performance tha
n AD620 and with low cost as well. Also, ADI has a big family of digipot, like
AD5241 (256 positions, I2C). You can find more choices (33 positions to 1024
positions) at http://www.analog.com/DigitalPotentiometer[2003-8-5 11:10:45]

[问：lr-lxm] 请问：片上电阻分压网络对输入信号的分压参数是否具有可编程的调节功能
？
[答：WenShuai] The voltage divider is fixed, you cannot program it. But we do
have parts that the input range can be programmed, AD766X for example.  [2003-
8-5 11:11:38]
[问：niumanke] Sigma-Delta转换器在保证最高精度的前提下,对被采样信号的频率有何限
制?
[答：Eagle] 也要符合采样定律。一般SD基于过采样，对滤波器要求会适当降低。  [200
3-8-5 11:12:00]
[问：lumingdsp] 请问，贵公司的Analog产品与TI的Analog产品相比，有什么优势所在？

[答：WenShuai] We are the lead in signal processing both in analog field and d
igital field.  [2003-8-5 11:12:11]
[答：WenShuai] The output is digital, and single-ended. Normally, in serial fo
rmat.  [2003-8-5 11:12:50]
[答：Mariah] The resolution of Sigma-Delta ADC is high, but the speed is low.
Sigma-Delta ADCs usually used in industrial field.  [2003-8-5 11:13:02]
[问：11067] 请就如下几个指标详细谈谈它对产品性能的影响
[答：WenShuai] Please send mail to china.support@analog.com, we will send mate
rial to you on your question.  [2003-8-5 11:13:32]
[问：ljsword] hi, can you give some tips on
how to design the application
board for such a high accuracy
[答：Adrian] There are evaluation boards available from ADI for many of these
Sigma-Delta ADCs that can achieve the high accuracy results.
Many of these have schematics or layouts available, so these could be followed
to get good performance.
There are many application notes and hints available on www.analog.com on powe
r supplies, grounding and signal routing.
Digital signals should be kept away from the sensitive analog inputs. Good cap
acitor decoupling is generally required, and care should be taken with groundi
ng.  [2003-8-5 11:14:01]
[答：William] Depending on the products, for some, one can adjust gain, offset
etc. for each channel independently.  For some multi-channel ADC, you can con
figurate the sequence of which the channels are sampled.  Please refer to the
datasheet for details.  [2003-8-5 11:14:42]

e 64KSPS, DSP Processor=ADSP2185L @ 52MSPS, Dash 40=(8Kx24 Prgm + 8Kx16 Data M
emory) or Dash 80=(16Kx24 Prgm +16Kx16 Data Memory), Vsys=+3V)  [2003-8-5 11:1
6:30]
[问：songhengli] 什么是过采样？
[答：WenShuai] It is the principle that the sample rate is far more than the s
ignal bandwidth. You can find it in the presentation.  [2003-8-5 11:16:49]
[问：wzy200163] 贵公司是否有USB控制类产品？
[答：WenShuai] The principle is different. Normally, SAR will be faster than t
[答：WenShuai] It is made fixed on chip. So you can say it is automatically us
ed.  [2003-8-5 11:18:40]
适，是不是接在地上最好？为什么REFOUT脚没有设定的电压值输出？
[答：William] REFCAP is used to provide a mean to stablize the voltage from th
e internal reference.  So one needs to connect decoupling capacitor to this pi
n.  Typically one would use a capacitor between 10-100nF.  Our recommended val
ue is 0.1uF.  REFOUT has a nominal voltage of 1.25V.  [2003-8-5 11:18:58]
它的模数转换器的精度如何,他与motorola的HS12DP256为控制器上的模数转换装置比较起
来有哪些显著的优点!!!
它的价格在国际市场上有优势吗,在国内市场上它的性价比如何.他有哪些型号对中国大陆
市场是受出口限制的.用这个产品会带来哪些"贸易壁垒"!!
它的开发工具以及培训如何得到,有哪些优惠?
[答：Wayne] ADI has a big series of Sigma Delta ADC products, from 16bit to 24
bit resolution (no missing code). We can reach 22.5 bit effective resolution.

I"ve not experience with Motorola"s part you mentioned. However, I would like
e world. We can reach high precision, with high conversion rate. For price que
stion, you can contact with ADI local office, or distributors (Excelpoint, Chi
natronic, Arrow, Future, and WPI).
All Sigma Delta ADC are not on the control list, you can purchase it easily fr
om distributors.
For evaluation or developing tools, you can get free example code, register se
ting, and application from www.analog.com.
And here is a tutorial on web for Sigma Delta:
http://www.analog.com/Analog_Root/static/
techSupport/designTools/interactiveTools
/sdtutorial/sdtutorial.html [2003-8-5 11:19:51]
[问：49836] 我设计的的一个产品检测一5K的信号用带通放大,但当移动电话(拨打时)靠近
会产生干扰,好象是后级偶合进去的,怎么办?
[答：WenShuai] This is the problem of RF inference. Use shielding should be OK
.  [2003-8-5 11:20:01]
[问：lyjsolar] 积分非线性15ppm是什么概念？
[答：Mariah] Integral Nonlinearity (INL)
The deviation of the transfer function from a reference line measured in fract
ions of 1 LSB using a "best" straight line" determined by a least square curve
fit.
ppm means part per million  [2003-8-5 11:20:24]
采集后的信号经MSC1211处理后回传给服务器。如果采用贵公司产品，仅A/D、D/A部分的成
本应该是多少?
[答：Eagle] How many bits are you need?
AD5308 (8 ch 8 bit DAC ) is very cheap.
AD5328 (8 ch 12 bit DAC) is also cheap.
You can also use ADUC831 (8ch 12bit ADC + 2 ch 12bit DAC + 8052 MCU + 62k Flas
h memory)  [2003-8-5 11:20:59]
则系统的有效位数能提高几位，是这样的吗？
[答：WenShuai] You can find the test conditions in the datasheets. Normally, t
he lower the input bandwidth, the higher the resolution.  [2003-8-5 11:22:26]

ry cheap.
AD7738 (24 Bit, Update Rate Max=15KHz, SNR=100dB @ 2KHz, Effective # Bits=19 &
8.5KHz, 8 CH SE or 4 Diff, Input Ranges=4 Diff=+/-0.625V or +/-1.25V or 8 SE=
0>+0.6250V, Ext Vref=+2.5V, Vsys=+5V & 18mA, I/O=Serial SPI, w/Input Buffer (I
b=200nA), Prgm Output Rates 300Hz to12KHz, Self Cal and per Ch System Cal, Mux
Output Pins)  [2003-8-5 11:22:58]
据说明
[答：WenShuai] You can find it in the datasheet. For example AD7705 is 98dB.
[2003-8-5 11:24:29]
[问：wzy200163] 请推荐多通道（4个以上），每通道增益独立可编程变化，采样频率较高
，漂移小且可对50Hz进行手控或自控，低功耗，16bit以上的器件。
[答：Eagle] AD73360L (6 Channel, 16 Bit A/D/Channel, Master Clock=16.384MHz, S
ample Clock=8.192, Sample Rates=8/16/32/64 KSPS, SNR= -73dB w/PGA=0, PGA Range
=0to +38dB/Channel, Group Delay=25msec, I/O=Serial, Vsys=+2.7V @ 26.5mA w/all
sections on)  [2003-8-5 11:24:38]
[问：qin] 请介绍高温热电耦的冷端补偿和测量线补偿?冷端补偿是否需要恒温装置?

[答：Mariah] There is an article to introduce the thermocouple signal conditio
ning. you can find that by the link below, please refer to chapter 7:
http://www.analog.com/technology/
amplifiersLinear/training/sensorSignal.html
In fact you don"t need a constant temperature device.  [2003-8-5 11:24:38]
出了产品了哪？要是有，能否提供一下联系方式？

[答：William] ADI is a large IC supplier world-wide for the energy metering ma
rket.  Our annual shipment is in the millions.  You can contact any of our sal
es office.  Please look up the telephone number on our website at www.analog.c
om  [2003-8-5 11:25:32]
进措施
[答：Wayne] We"re offering higher channel number, higher conversion rate than
before. For example, AD7732/4 support +/-10V 2differential/4 single end inputs
, can work at 15KHz sample rate. AD7738 support +/-2.5v 4 differential or 8 si

AD8221 (Vos RTI=150>500uV, TCVosi=0.8>2uV/C, Gain Error=0.1>0.35%, @ Av=1>1000
, CMRR=70>80dB @ fin 10KHz Av=1, BW=1MHz, SR=1.5V/usec, S/time=7usec to 0.01%,
Vsys=+/-15V @ 1mA)  [2003-8-5 11:25:49]
[问：tomzhao1] 对信号采样能达到的精度怎么计算？
[答：WenShuai] You have to calculate the ENOB according to the SNR. ENOB=(SNR-
1.76)/6.02  [2003-8-5 11:26:11]
[问：qin] 如何消除传感器噪音和非线性对测量的影响?
[答：WenShuai] You can do system calibration. Normally, ADI parts will have th
is function.  [2003-8-5 11:27:05]
[答：Grainne] They are typically 2-3ppm INL (intergaral non-linearity). We (AD
I) usually specify the maximum, which is important for the precision systems.
Look into datasheet. Michal  [2003-8-5 11:27:42]
[问：abolas] 你们所说的系列的分辨位数是在什么条件下测出来的？是在输入为0v的条件
下吗
[答：Mariah] Under what conditions do you test the resolution of these sigmal-
delta parts? For example,is the input 0 V?  [2003-8-5 11:29:46]
[问：zgd8964cn] 尊敬的专家：
兼容性如何？是否可将其连接到普通数据采集卡上？
[答：WenShuai] Our ADC has the evalution board, which is controlled by the PC.
Then the data can be processed in PC. And we also have a data sampling card u
sed DSP.  [2003-8-5 11:30:28]
匹配?
[答：Eagle] Normally we use IN-AMP such as AD620 and AD8221. It has high input
impedentend. Some times 2 JFET input type AD8620 is used to buffer the input.

AD8620 (Dual, Vos=150>250uV, TCVos=1.5>3.5uV/C, Ib=10pA, BW=25MHz, SR=40V/usec
, enoise=6nV/sqrthz, CMRR=90dB, Vsys=+5/->26V @ 3.5mA, No Phase Reversal)  [20
03-8-5 11:30:41]
，请推荐一款。
[答：William] There are many models you can choose, e.g. AD676, AD976, etc. de
pending on the type of interface/reference (serial or parallel) you need.  I w
ould like to point out that unipolar input can often be used with a simple vol
tage shift of bi-polar signal at the input.  This can often leads to a signifi
cant reduction of system cost.  [2003-8-5 11:30:49]
都很大
design rules including grounding. To reduce flicker is to reduce noise.
2) Adopt lower sampling rate, or using more oversampling manner, using averagi
ng manner can help some as well.  [2003-8-5 11:30:51]
[答：Grainne] This depends on the part and volume required.
Many of the sigma parts are held in stock so that lead time would be short.
The price depends on the volume you want. Our latest part the AD7789 has a pri
ce of just over \$2 in 1K volume. This is a 24 bit part and we also have lower
cost 16 bit versions. You should contact your local representative for a more
accurate quote and lead time when you have picked a part that suits.
Grainne [2003-8-5 11:31:48]
[问：wswtiger] 1、如果我要实现＋20dBm到-74dBm的信号采样，在前端信号的调理部分应
当采用什么样的方式来实现自动的动态范围调整呢？
2、在接近40MHz的采样时钟下，如何确保设计得到最佳性能
3、谢谢
[答：WenShuai] You have to use RF power detector and the VGA, AD8304 should be
OK, and ADuC812 can control it. Any further technical support needed, please
call 800 810 1742.  [2003-8-5 11:31:49]
[问：shghu] 如果需使用无线数码传输音频信号,请问如何解决发送端和接收端的时钟同步
问题?
Email: china.support@analog.com [2003-8-5 11:33:23]
[答：WenShuai] If the switching time can meet your requirement, then you can u
se it.  [2003-8-5 11:35:13]
[问：chengangangel] 是什么形式的滤波器，几阶，我想要3阶的滤波器，怎么扩展？

[答：William] I"m not sure which filter you are referring to.  Inside sigma-de
lta ADC, we uses FIR filter, typically sample-and-hold.  For some of our produ
cts, you can control the degree of interpolation by configurating the internal
programmable filter.  [2003-8-5 11:35:28]
[答：WenShuai] No, some parts have PGA, some don"t have. You have to get detai
led information from their datasheets.  [2003-8-5 11:37:06]
[答：Grainne] We guarantee stability. This the unique design that ADI uses for
We use accelerated life testing during our qualification process so that we ca
n predict whether a part will be stable and our specifications are based on th
is data.
So the specifications in the datasheet are based on life testing.
Check out for example the AD7730 and AD7731 datasheets: 25nV/1000 Hours (Offse
t drift vs time)
Grainne  [2003-8-5 11:37:12]
论上可以达到的最高分辨率是多少？
[答：WenShuai] You can get 14-bit peak-peak resolution according to the datash
eet  [2003-8-5 11:38:26]
的系统可以保证13位以上的精度？
ADG726 (16 Channel Differential, Ron/Match=5.5/0.8 ohms, transistion Time=45ns
ec, Break Before Make Delay=15nsec, -3dB BW=34MHz, Crosstalk/Off Isolation= -7
2/72dB @ 1MHz, Vsys=+2.7 to +/-2.5V @ 20uA, I/O=P4 w/Enable)
ADG706 (16 Channel Single Ended, Ron/Match=5/1.2 ohms, ton/toff=50/14nsec, Bre
ak Before Make Delay=30nsec, -3dB BW=25MHz, Crosstalk/Off Isolation=@ 10MHz =
-60/60dB, Vsys=+2.7 to +5V or +/-2.5V @ 1uA, I/O=P4 w/Enable)  [2003-8-5 11:38
:32]
[答：WenShuai] No, it will work until you stop it or it has been destroyed.  [
2003-8-5 11:39:07]
[答：WenShuai] Sure. AD7732 can accept +/-10V input signal.  [2003-8-5 11:39:4
9]
[答：WenShuai] It can, but should be worked under overvoltage mode.  [2003-8-5
11:40:15]
[答：WenShuai] Normally, the self-calibration should be used every time the pa
rt is power on.  [2003-8-5 11:40:57]
[答：WenShuai] It is fixed in the part.  [2003-8-5 11:41:16]
[答：William] For this type of application, you need an ADC which can perform
simultaneous sampling to perserve phase information.  Typically, sigma-delta t
ype is not most suitable.  SAR-type with sample-and-hold amplifiler is needed.
The input impedance would be an issue if the output impedance of your source
is high.  But this can be easily solved by adding external buffer.  [2003-8-5
11:41:47]
它的优势是什么，工作原理又是什么？？
[答：Mariah] The resolution of Sigma Delta ADC is extremely high. And most of
the parts have integrated signal conditioning circuit. Some parts also allow m
ultiple input range and mode. They are usually used in industrial field. You c
an get the basic knowledge of Sigma Delta technique by the link below:http://w
ww.analog.com/Analog_Root/static/
techSupport/designTools/interactiveTools/sdtutorial/
sdtutorial.html  [2003-8-5 11:41:59]
源，电池）
[答：WenShuai] Normally, for anlog signal, the linear power supply and battery
should be used, the switching power supply should not be used. If you want to
use it, take care of the filtering.  [2003-8-5 11:42:17]
[答：Grainne] Yes, all our sigma-delta have an internal FIR filter. On most of
our parts it is "SIN3" filter. The AD7730 and AD7731 have a second stage 22-t
ap filter resulting very low noise, 50/60 Hz rejection and well defined stop-b
and.
Michal.  [2003-8-5 11:43:00]
[问：jensen.lee] 若被采集信号是pA级的话，请问如何保证精度
[答：WenShuai] You have to use a precision amplifier to amplify it, then input
3:26]
[问：98379] 我设计的一个系统中需要一个DAC，要求的噪声指标相当严格，可以选用什么
器件，设计时需要注意些什么？
[问：zjz88] 在电子称中的应用，不考虑其它外在任何干扰吗？
[答：William] Of course not, you need to consider many external interference s
ources such as EMC and temperature.  EMC problem can be avoided by careful pcb
layout.  However, to avoid temperature drift one would require careful compon
ent selection.  For example, most amplifiers used in weight scales are chopper
type with ultra-low drift.  For ADC, one also needs very low drift specificat
ion.  [2003-8-5 11:44:18]
[问：qihong] 片上设置分压电阻，是否会影响输入阻抗？
[答：WenShuai] Should be, but we will specify it. And will make it a fixed val
ue.  [2003-8-5 11:44:46]
[答：William] Sigma-delta ADC uses over-sampling and noise shaping to achieve
much lower noise performance than other type of ADC.  SAR, on the other hand,
has much higher speed.  [2003-8-5 11:46:33]
吗？
[答：WenShuai] Normally, digital signal will be more robust than anlog signal.
Also, 4-20mA current loop can be considered. AD421 is a good current loop par
t. Also, ADuM1100 can be used as the isolation coupler.  [2003-8-5 11:47:15]

[问：yjems] What is decimation?
[答：Grainne] The sigma-delta architecture uses oversampling, i.e., the modula
tor runs much faster that is the bandwidth of interest. The modulator output i
s usually only 1-bit resolution, for eample 32kHz rate. Then there is a digita
l filter, that filters the output data to get more resolution at lower speed.
For example 18 bits at 50Hz data rate. DECIMATION is how much does the digital
filter average the data to get the resoltion.
Michal.  [2003-8-5 11:48:06]
[问：ljp] 如何判断单极点RC滤波器足够用?有无计算公式或参考资料?
[答：WenShuai] You can simulate it. To find out its frequency domain property.
I think you can find it in textbooks. <<System and Signal>> for example.  [20
03-8-5 11:48:19]
干扰能力的关键是什么？
[答：WenShuai] Normally, ADI parts can reject it in 98dB (AD7705 for example).
This is a property of the part.  [2003-8-5 11:49:17]
[问：teiliyuan] 我打算使用16比特A/D，串行输入输出，采样频率100ksps-250ksps,8ch
,请问使用哪种A/D更好？好购买吗？
[答：Grainne] We would suggest that you look at some of the AD772x family data
sheets.
Grainne  [2003-8-5 11:49:39]
[答：Adrian] The BB parts require a long settling time because of the digital
filter. The settling time is 5 output cycles, therefore the effective conversi
on time is only 8kSPS.
Also, the resolution quoted is "Effective" resolution rather than "Peak-To-Pea
k" resolution specified on most ADI datasheets. 19-Effective bits is equivalen
t to 16.3 bits peak-to-peak.
ed conversion rate of 8.5kHz, ie this includes the full settling time of the A
DC.
Therefore in terms of performance it is better than TI/BB. The AD7738 also inc
ludes extra features such as internal buffer, low-drift "chopping" mode, input
multiplexer, crystal oscillator, calibration modes etc.  [2003-8-5 11:50:02]

[问：93481] 如何测试出SNR,用什么仪器，方法？
[答：WenShuai] For ADC, you have to use FFT, then calculate it. For DAC, you h
ave to use spectrum analyzer.  [2003-8-5 11:50:56]
统可以保证13位以上的精度？
一定要有偏置电压？如果偏置电压从一个电阻和二极管构成的电路中取自二极管正向压降
，这样的设计是否合适？
谢谢!
ine), both are 16 channel differential multiplexers. The on resistence is 3.5/
4 ohm.
83, with onchip current sources, which can help you easily finish design of RT
D measurement.

2.) The only thing you need to check is whether the common voltage is within t
he range of DATASHEET specs. You need to check whether your"re using bipolar i
nput or unipolar. Also, if you use diode for bias, it may cause temperature dr
ift problem.  [2003-8-5 11:51:58]
[问：93481] 一般说，双层pcb板上的power、ground 的noise会达到什么量级，我们测试
的竟然有50mv，这样正常么？
[答：Eagle] 似乎太大。可考虑用特粗地线，甚至象高频电路板一样，用表贴元件，将另
esolution @ 16.6 Hz)就是差分输入。还要注意布局，电源滤波，分地， 等。  [2003-8
-5 11:51:58]
[问：ljp] 取样保持电路如何进行计算?保持时间的限度和取样频率有何关系?有计算公式
?
[答：WenShuai] S-D ADCs don"t need the sample and hold part. And you can find
the equations from the textbooks, <circuit principle> for example.  [2003-8-5
11:54:46]
?
[答：William] Sigma-delta ADC has poor response to spike because of its digita
l filter.  But most products have limiter so they will recover from the spike.
One needs to be careful and use external components to limit the part"s expo
sure to external spikes.  [2003-8-5 11:54:58]
？
[答：Wayne] Sample rate; effecitve resolution under certain sample rate; 50/60
HZ rejection. Also, for portable application, maybe power dissipation......
It"s all depending on your application.  [2003-8-5 11:55:05]
[问：xingge] 请问，在小信号放大之前怎样避免接地噪音的干扰呢？
或 光耦隔离。  [2003-8-5 11:55:31]
amplifier and a high-impedance input buffer, therefore for many applications
the sensor signal can be connected directly to the ADC inputs, with only a sim
ple RC filter required for anti-aliasing or EMI rejection.
If an external op-amp is required, the on-chip buffer means the input current
is very low. Without a buffer, the input currents due to the sampling capacito
rs in the ADC can be quite high, therefore a high-performance op-amp is requir
ed to supply the dynamic current required without causing errors due to incomp
lete settling.
This is particularly important for high-spped Sigma-Delta ADCs such as the AD7
[答：Grainne] The AD7730 would give the best performance when connected direct
ly to the load-cell. It has 40nV RMS noise in +/-10mV input. I.e., if the load
-cell gives output signal of 20mV, the resolution of 80000 counts, i.e., 16.5
bit peak-peak resolution. The AD7730 was designed to be connected directly to
the load-cell, therefore, it has many other on-chip features such as TARE DAC,
on chip self and system calibrations etc.
Most of other parts with on-chip PGA could be connected directly to the load-c
Michal.  [2003-8-5 11:56:09]
[答：William] No, the minimum gain is 0dB so it cannot attenuate signal.  If a
ttenuation is needed, one can use external components.  [2003-8-5 11:56:29]

[问：junkai_cao] 这些器件都具有高的转换精度，请问接地有什么考虑
[答：Wayne] Simple, please use single ground (analog ground). For details, you
can refer to a book here:
http://www.analog.com/technology/
amplifiersLinear/training/sensorSignal.html [2003-8-5 11:56:50]
[问：qin] 什么是4-20mA回路?
[答：Eagle] 标准，可到www.analog.com 用keyword search.  [2003-8-5 11:57:00]

[问：chenqs] 输出更新率和-3dB陷波频率有何关系？
[答：WenShuai] Updata rate = 0.262 * (3dB bandwidth)  [2003-8-5 11:58:07]
位总是跳（一般能到20位不跳已经很不容易了）。请问还有什么要注意的吗？
[答：Wayne] Please note when you realize 20bit no flicker, in fact you"ve reac
hed at 22.7bit effective resolution. (please refer to the seminar material for
the 2 resolution concept).
By other words, you"ve done a good job.  [2003-8-5 11:59:04]
[问：tomzhao1] 有那些办法防止采样到的非法数据？
[答：William] Firstly, you need to follow the timing requirement of the produc
t.  Secondly, for sigma-delta ADC, if one uses a mux front-end, you need to "f
lush out" the previous data before the data is valid after one switches channe
l.  Our newer products that have mux built-in will automatically clear out the
incorrect data and ensure the output is correct.  [2003-8-5 12:00:00]
比，有那些优点？跟51单片机相连需要注意那些事项？我应该使用那个通道作为信号的输
入端比较好？谢谢！打扰了
[答：WenShuai] This is the name of one kind of ADC. The advantage is its high
resolution and small size. When connect to the MCS51, take care of the groundi
ng and power supply decoupling. ADI have ADuC816/24 that integrated 51-MCU and
S-D ADC. You can consider it.  [2003-8-5 12:01:16]
[问：wzy200163] 是否有多通道（4个以上），每通道增益可编程，又可抑制工频干扰，精
度可在16bit以上的产品？

[答：Grainne] The linearity is inherently very high and guaranteed by architec
ture. The industrial/instrumentation sigma delta ADC are effectively only 1-bi
t ADC, the resolution is achieved by filtering the data in time.
The DNL is really 24-bit, the INL is typically 1-2ppm (guaranteed 10 - 15ppm m
ax, depends on part). Note, that the linearity is specified including on-chip
buffer, PGA etc. Michal.  [2003-8-5 12:01:57]
[答：WenShuai] RMS resolution is used by other kinds of ADC. We specify this t
o the peak to peak resolution is that when you select s-D ADC from difference
vendors you have to know this. p-p resolution = rms resolution - 2.7 bit  [200
3-8-5 12:04:05]
audio amplifier. We"ll have an new part ADDVR801 for DVD R/W.

ADDVR801 is Single Chip DVD Recordable Audio Codec
Offers Performance and Functionality for DVD Recordable systems at an attracti
ve Cost
Features Stereo ADC (with ALC) – 102 dB DNR
Stereo DAC – 105 dB DNR Sample Rate Converter (SRC) – 125 dB DNR Selectable
Inputs and Outputs
Phase Locked Loop (PLL) Audio Clock Generator
Develops required on-chip and off-chip system clocks Flexible Digital Audio In
put and Output
PCM and S/PDIF Control Interface
AD1955 (Dual, 24 Bit, Data Size=16/18/20/24 Bit, 216KHz, fs=246/384/512/768*Fs
clock, Volume Control=14 bit Clickless, Dynamic Range=122dB, THD+N= -108dB, SN
R=120dB, Vsys=+5V @ 59mA, SPI I/O for control, Digital I/O=all types, Analog O
utput Diff, w/SCAD phase modulation & mute Detect, fclk=12.288MHz)
AD1954 (Triple, 24 Bit, w/ 26x22 DSP Core, DSP=26MIPS, THD+N=100dB, SNR=112dB,
Stopband Atten=75 dB, 7 BiQuad Digital Filter Sections/CH, Variable delay=0>6
msec for Speaker Align, Volume Control=3 H/Ware, Data I/O=All, Vsys=+5V @ mA,
w/Phat Stereo)

AD1836 (16 Bit, w/3 Stereo D/A"s 2 Stereo A/D"s, 16/18/20/24 Bit Data, 96KHz S
ampling, ADC & DAC SNR/DR=105dB, THD+N= -97dB, on chip volume control/ADC gain
control, Vsys=+5V @ 186mA, w/3 Line to Line Inputs, see AD1836A)  [2003-8-5 1
2:04:41]

[答：William] Yes, there are many products can be used for this voltage range,
e.g. OP1177 (4th generation OP07), OP27, etc.  [2003-8-5 12:04:59]
[问：wangxw] 请详细解释一下noise free 分辨率？
[答：WenShuai] This means, there will be no code flick in the output.  [2003-8
-5 12:05:15]
[答：Eagle] 主要由精度决定。  [2003-8-5 12:05:24]
[答：Wayne] We"ve VGA ADL5330 (not PGA) which has bandwidth to 2.7GHz.
For DGA, AD8369 with BW as 500MHz.  [2003-8-5 12:05:40]
有一些别的方法？
[答：Grainne] Depends on what is important for the application. The instrument
ation and industrial applications usually require high linearity and high reso
lution, therefore, INL, no-missing codes and noise-free (i.e., peak-peak) reso
lution would be the key specifications. All of these are  guaranteed and speci
fied in our datasheets.
Michal.  [2003-8-5 12:05:56]
分析仪？
[答：WenShuai] You can consider Agilent.  [2003-8-5 12:06:22]
准确性?
[答：Eagle] S-D ADC can get higer resolution while decrease sample Rate.
AD7791: 19-Bit p-p Resolution (21.5 Bits Effec-tive
Resolution) @ 16.6 Hz [2003-8-5 12:07:33]
[答：Mariah] If you wants to get the material, please call 800-810-1742 which
is the china application support free number.  [2003-8-5 12:07:55]
[问：21193] 片上的temp sensor 做什么用的?
x MicroConverters.
This can be used for measuring the ambient temperature in applications such as
Pressure measurement, where the temperature of the sensor needs to be known f
or temperature compensation.
The temperature of the ADC will be close to the temperature of the sensor if t
he ADC is located close to the sensor.
On the AD7719 the temperature sensor is connected to the second Auxiliary ADC,
so temperature measurment can be made at the same time as the primary input s
ignal.
The temperature sensor on the AD7719 is not calibrated, so the absolute accura
cy is quoted as +/-8"C typ. However if the user-system is calibrated in the Fa
ctory at two temperatures, the temperature sensor accuracy will be improved to
approc 2 degrees..
The ADuC824 Sigma-Delta MicroConverter includes a calibrated temperature senso
r, and achieves 2"C typ accuracy.  [2003-8-5 12:08:05]
dio ADC that use sigma-delta architecture.  [2003-8-5 12:08:25]
，采样率却达不到预计的结果，请问是什么原因，如何解决呢？谢谢
[答：WenShuai] When you use S-D ADC, you must take care of the swtiching time
between channels. Normally, there will be 3-4 time spend for the digital filte
r to settle. Any further technical support needed, call 800 810 1742, please.
[2003-8-5 12:08:34]
[问：jielemon] 能否介绍一下SIGMA-DELTA 技术在视频方面的应用
[答：Wayne] Sigma Delta is low speed precision ADC (lower than xx KHz for 24 b
AD1852/3/4/5)...... Video signal can be higher than 6MHz BW, therefore, no Sig
ma Delta ADC for this application.
If you"ve interested in video application, you can find video decoder (ADV7183
73xx).  [2003-8-5 12:09:58]
[答：WenShuai] Please refer to the principles of the S-D ADC of the presentati
003-8-5 12:10:14]
大
[答：William] The current signal is usually very small at light load.  Dependi
ng on what you need to do, if what you need is only the current for RMS/peak c
alculation, you will have a lot of noise at the low-end of the dynamic range.
You can imporve the signal level by using a sensor with larger output.  [2003
-8-5 12:11:03]
[答：Mariah] Filter is not needed for Sigma Delta ADCs. But for other kinds of
ADCs such as SAR, anti-aliasing filters are needed.  [2003-8-5 12:11:33]
[问：ljsword] How to implement high precision resistor?
[答：WenShuai] ADI doesn"t provide resistors except digi-POT.  [2003-8-5 12:11
:36]
ormation on our distributors.  [2003-8-5 12:11:46]
[答：Eagle] 一般依靠前面的仪表放大器保证。
For example, AD8221 CMRR at 10kHz
G = 1    70  dB
G = 10   80 dB
G = 100  110 dB
G = 1000 110  [2003-8-5 12:12:12]
6位的分辨率.
[答：Grainne] Not to affect the 16-bit accuracy, the ch-ch isolation should be
better than 96dB (calculated as 20xlog(2^16). We usually don"t specify ch-ch
isolation in our datasheets because it is very good (>>120dB) on our mult-chan
nel part (AD7718) and would be hard to test it.
Michal.  [2003-8-5 12:13:04]
[答：Eagle] Differential amp such as AD8138 with low distortion. You can also
use some VGA (AD8332 ) with intergated differential driver.  [2003-8-5 12:14:2
5]
[问：jdnjb] 我在北京，如需要技术支持打那里电话。
[答：WenShuai] You can call all over China the toll-free number 800 810 1742.
[2003-8-5 12:14:35]
产生影响？需要采用什么样的仪器测试？
[答：Wayne] It"s basically a PCB layout (including grounding) question. Theref
ore here is a link for design guide:
http://www.analog.com/technology/
amplifiersLinear/training/sensorSignal.html
Also, you need to make sure all related devices are selected properly, like pr
ecision amplifier...
You need to use FFT to measure its performance. You can use ADI evaluation boa
rd to do test directly.  [2003-8-5 12:14:59]

[答：WenShuai] You have to buy the evaluation board and do evaluation.  [2003-
8-5 12:15:33]
[答：Wayne] Some part can reach 15KHz sample rate, like AD7738, AD7734.  [2003
-8-5 12:15:34]
[答：WenShuai] 1 bit ADc is comparator.  [2003-8-5 12:15:54]
[问：ljsword] If i have the 35m 10bit ADC, how to modificate it to get the 100
[答：WenShuai] You can use several such ADCs, and input it to the same process
or. Get the clock 3X should be enough for you.  [2003-8-5 12:17:22]
[问：ljp] 输入端如何对布电容进行补偿或消除?
ADCs, unless the input signal has high-impedance.
If there is a large resistance on the input signal, then stray capacitance on
the ADC input can cause gain errors if the ADC input is not buffered. This is
a praticular problem for high-speed Sigma-Delta ADCs.
that can be tolerated for a given Capacitance when unbuffered.

Using an on-chip buffer allows very large resistance and capacitance without c
ausing gain errors. Therefore unmatched RC filters can be placed on the input
for EMI rejection etc.

2) is a Rail-To-Rail buffer, allowing input signals to within 100mV of Vdd and
Ground, while the AD7738 accepts inputs to within 300mV of Vdd or Ground. Thi
s is a major benefit of Analog Devices Sigma-Delta ADCs.  [2003-8-5 12:17:36]

[问：chengb] How to use them to measure True RMS.
ample.  [2003-8-5 12:17:59]
[问：lxq00008] 请问贵公司有没有能将1mHz正弦信号的有效值直接转换成数字信号的芯片
?有的话,精度有多高?
[答：William] We don"t have any product which directly calculates this.  Howev
er, you can use a sigma-delta ADC to easily achieve this with very high accura
cy.  [2003-8-5 12:18:36]
[问：zhaoliang0804] Can you give us some examples about the fulfiled applicati
[答：WenShuai] Refer to page 20-41 of the presetation.  [2003-8-5 12:18:59]

[问：92583] 具体如何设置50Hz抑止参数。谢谢。

[答：Wayne] Every part has its spec on how to realize 50/60Hz rejection. Basic
ally it"s related to the update rate of the ADC.  [2003-8-5 12:19:19]
[问：lxq00008] a/d转换后数据处理我要使用正切表查询,我怎样能在最小数据位数下取得
0.1度的分辨率?这里我指的是tan(0.1),tan(0.2),...,tan(89.8), tan(89.9),括号内表示
角度.

样吗？
[答：Mariah] No. For sigma delta ADCs, PGA is integrated. So you needn"t to do
signal conditioning such as amplifying.  [2003-8-5 12:19:24]
[答：WenShuai] AD7705 is not an obsolete part, ADI will continue produce it. W
hat does upgrade mean?  [2003-8-5 12:19:43]
[问：cheenle] 请问如何保证货源和外围配套器件的供应？我觉得除了芯片的精度外，外
[答：William] We don"t recommend external components.  The designer needs to c
onsider the system level accuracy requirement and assign error tolerance to ea
ch of the component.  [2003-8-5 12:20:02]
[问：ljsword] why the low power ADC need low power at low speed and the high s
[答：Grainne] There are alwaeys capacitors (real capacitors and parasitic capa
citances) in the ADC architecture. These need to be charged / discharged durin
g the conversion and with change of the analog input signal. Faster conversion
means faster charging and needs higher currents and higher current budget ins
ide the part. Therefore, higher speed requires more curent (power).

Traditionally we have seen the higher speed parts going into applications such
as industrial systems where power is not as critical a factor. And the slower
parts such as AD7788 being used in portable application like hand held multim
eters where lower power is required.

However we are always looking to reduce power as much as technically possible
so it is likely that newer sigma delta ADCs operating at the same speed will c
onsume less power even at higher speed.
[2003-8-5 12:20:13]
[答：Eagle] Input frequency should be slow, do not switch input channel very f
ast. It"s common issue we meet.  [2003-8-5 12:20:30]
[问：wenedi] 请问在高频的直接数字频率合成器中（如20mhz），16位的数模转换器需要
考虑哪些问题
[答：WenShuai] Refer to the link below:
/54011189110016515183343533079104002
517DDStutor.pdf  [2003-8-5 12:20:53]
[问：xhtwork] 内置参考电压，20位精度，速度无要求，最便宜的器件是什么？
[答：William] What"s the lowest cost, 20-bit accuracy sigma-delta ADC which ha
s internal voltage reference?  [2003-8-5 12:22:37]
[答：Mariah] You must consider the frequency and converting speed for your nee
d.  [2003-8-5 12:22:52]
?
[答：Grainne] It is inherent of the sigma-delta architecure, however, to achie
ve and keep 24-bit no-missing codes need really careful design.
We are focused on high resolution, we do test the no-missing codes performance
during our qualification for each part to be sure that the no-missing codes p
erformance has been really achived.
Michal.  [2003-8-5 12:25:14]
[问：gzg317] 设计时,对模拟地和数字地应注意哪些问题?
分。
You can down load some technical support seminar seminar in the technical supp
ort page in www.analog.com. Also refer to AN-202 and AN345.
or" Practical Analog Design Techniques  "
Section 9 Hardware Design Techniques

[2003-8-5 12:25:44]

[答：Adrian] These CMOS ADCs contain diodes to Vdd and Ground internally for E
SD protection that clamp the input signal to approx 600mV beyond Vdd and Groun
d. However these diodes can not conduct current indefinitely, therefore the vo
ltage on the ADC pins needs to be limited if an over-voltage is likely to last
for a long time.

This can be done using external diodes. Alternatively, an external resistor ma
y be sufficient to protect the ADC. Provided the maximum total input current d
uring overvoltage is limited by the resistor(s) to approx 10mA, the ADC should
not be damaged, although the conversion accuracy on another channel may be af
fected.
The input buffer on the ADC allows large resistors to be used for protection o
f the inputs, with a leakage spec of 1nA on many ADCs.

There are Sigma-Delta ADCs from Analog Devices with Resistor Inputs than can t
olerate large voltages directly. The low-power AD7707 can accept +/-10V input
directly on the High-Voltage channel, while the High-Speed AD7734 and AD7732 c
an accept +/-16.5V inputs without additional protection.  [2003-8-5 12:26:40]

[答：WenShuai] The sampling rate is decided by the Nyquist sampling theory. Sa
mpling rate > 2 * signal bandwidth.  [2003-8-5 12:26:51]
[答：Wayne] Some part can reach 22.5 bit effective resolution, like AD7719/18,
AD7791....., it"s also depending on the sample rate you used.  [2003-8-5 12:2
7:11]
[答：Grainne] We do not sell IP and there may be some cores for sale on the ma
rket but you should be very careful about how accurate the core is.
Grainne  [2003-8-5 12:27:20]
[答：WenShuai] Some high speed ADC has the PLL. AD9861/2 for example.  [2003-8
-5 12:27:59]
[答：Eagle] 要看对精度的要求和最小分辨率。  [2003-8-5 12:29:07]
[问：hawkzone] For ADI"s multi-channel ADCs, can they convert data in a cycle
mode?
[答：Grainne] Yes, the AD7732 /34 /38 /39 were designed for multi-cannel appli
cations and these can cycle between channels automatically. These parts have m
any other features such us per channel settings, per channel calibrations etc.
to really fit into multi-channel applications.
Michal.  [2003-8-5 12:29:59]
[问：wu-2003] 我的输入是40KHZ-500KHZ，信噪比要求大于60dB，请问选用何种器件较为
合适？
[答：Mariah] sigma delta ADCs can not satisfy your requirement. You can consid
[2003-8-5 12:30:04]
[问：lxl9726] 我想做一个可变增益放大器，但信号的频带很宽，约60MHz，而且信号的幅
度在0.1mV到50mV之间，要求成本在50元以下，请问怎么做？谢谢！

The absolute gain is specefied as -0.8dB to +0.8dB at 1kHz.
[2003-8-5 12:30:52]
[答：William] The main source of error comes from noise and temperature.  Also
, because the accuracy is so high, so one needs to be very careful of the sign
al routing on the pcb.  [2003-8-5 12:31:53]
不能提供此类的产品！！
AD7863 (14 Bit Dual, 200KSPS, INL=1LSB, DNL=1LSB, Fclkin Int, Vin=0>+2.5V, 0>+
5V+./-2.5V, +/-5V, +/-10V,Vref Int=+2.5V, SFDR=82dB @ fin 100KHz, THD= -82dB @
fin=100KHz, SINAD @ fin 100KHz=78dB, Vsys=+5V @ 25mA, I/O= P12 Tri-State, w/2
Single Ended Inputs/ADC, Shutdown)  [2003-8-5 12:31:55]
[答：Wayne] Chopping technology is with long history, not patent of ADI. Howev
er, ADI has its own architecture of chopping realizing. I think you"re asking
...
AD8628, (we"re not simply calling them chopper amp, but auto-zero amp), you w
ill find its performance is much better than some other products on the market
.  [2003-8-5 12:32:00]
[问：huang
什么？
//www.analog.com/technology/
amplifiersLinear/training`
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Vos(85℃)= 25uV+60uV=85uV. 如果放大电路的Gain改为100,则最大输出失调电压就为8.5mV。这是最差的情况。   关于输入失调电压的测试在"运放参数的详细解释和分析-part2，如何测量输入偏置电流Ib，失调电流Ios...
• [1]重庆凌卡分析仪器有限公司,重庆400041 [2]北京北分麦哈克分析仪器有限公司,北京100095 　  摘 要 本文集中列出在线气体分析工程技术常用名词术语180条，力求给出比较规范的定义或解释。  关键词　在线分析...
• 电系魔法师成长之路—仪器仪表学习（二）设计T型和Π型衰减器 一、用途 ​ 衰减器是一种提供衰减的电子元器件， 广泛地应用于电子设备中，它的主要用途是：（1）调整电路中信号的大小；（2）在比较法测量电路中，可...
• 前言2020年2月24日加拿大研究者Jie chen在《Scientific Reports》发表的题为“Secondary Metabolites Profiled in Cannabis Inflorescences, ...本研究首次尝试全面分析植物各个部分的次生代谢物组。同时，本篇...
• 红外光谱分析(IR)分析原理：吸收红外光能量，引起具有偶极矩变化的分子的振动、转动能级跃迁。谱图的表示方法：相对透射光能量随透射光频率变化。提供的信息：峰的位置、强度和形状，提供功能团或化学键的特征振动...
• basICColor catch 5 Mac 破解版是一款适用于所有颜色测量需求的测量软件，可用于测量多个输出目标的软件：线性化，分析和质量保证目标，支持来自所有领先制造商的各种测量设备，非常专业强大，需要的朋友欢迎下载...
• ## R语言与统计分析

万次阅读 2015-12-16 11:20:29
R语言与统计分析 汤银才 主编 高等教育出版社 二○○八年五月 内容介绍 本书以数据的常用统计分析方法为基础，在简明扼要地阐述统计学基本概 念、基本思想与基本方法的基础上，讲述与之相对应的R函数的实现，...
• 在购机时需注意仪器的测色性能(Δλ=2nm、3nm、10nm);测色精度,长期重现性,防止配色误差;测色头子要坚固耐用。 计算机主机是对分光光度计测色结果进行分析处理的硬件基础。对计算机的配置要求是能满足配色软件及当前...
• 而数字信号处理部分，我觉得提取心率和呼吸并非困难的事情，只要压力传感器的噪声小于一定的范围，通过对数据做滤波与傅里叶变换，提取心率和呼吸率并非难事，之前一直做地质探测仪器，地震波在uV级别时，通过滤波...
• 2015-2016开发的项目 基于STM32F429动态信号测试分析系统 HP-DJ8125M 动态信号测试分析系统 中文版 HP-DJ8125M...

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