模数转换器（ADC）的基本原理ADI

简介：ADI新型转换器

问：对于干扰比较严重的检测环境,除了选择双积分型A/D芯片外,其他几种类型的A/D芯片,选用那一种比较好?
答： I would like to suggest you to use the ADC with differential input ADC to avoid the noise interference.

问：请问专家：
9对ADC）PCB设计时，有关地的处理，有人说数字与模拟分开最终会集电源的大电容处，有人说此两地线应再ADC下方相接，4层板有人赞成此两地分离隔开，也有人赞成不分开隔离，只在布局时分块，而地平面用统一的地平面
我应怎样来处理？对2层和4层请分别指教，谢谢！
答： The is some different in high speed and low speed. For high speed (>10M SPS), use a signal Ground in layer 2 of 4 layer, bottom layer in 2 layer PCB. For low speed ADC (< 1M SPS) use signal connect point under ADC or at power connect point (need two

问：传感器采集的微弱信号经运算放大器放大后输入A/D模数转换器时，采用何种A/D比较好？
答： Basically it depends on the signal amplitude after amplifier, and the resolution you need. However, for small signal, suggest to use bridge, and you can use AD7730 for directly handling bridge signal. You can also refer to the materials on below link: http

问：在ADC的应用中，信号、ADC、CPU、电源等部分的模拟地和数字地应如何连接？
答： Signal point at low frequency, whole ground layer and connect as near as possible for hign spee.
Please refer befor answer.

问：1.二阶过采样为128倍，一位量化的Sigma—Delta AD的理论上可以达到16bit的精度，在实际低频情况下可以达到多少位？原因是什么？
2。如何验证sigma—delta AD调治器的信噪比？
3。请讲一下Pipeline AD 中数字纠错的原理。谢谢！
答： 1. It can reach 24-bit in parctice. The reason is the noise shaping technology used in this kind of ADC.

For more information you can refer to the following three application notes provided by ADI:
AN-283, AN-388, AN-389

问：1.多通道高速模数转换器的设计应用要注意的问题。
2。采集两路300-4000KHz音频信号选用什么型号的A/D芯片最合适。？
答： 1. Simply you need to note PCB layout, supply de-coupling, grounding, clk, digital signal buffer, impedance match. Normally you can find these kind of imformation from the datasheet, also you can refer to the material of below link:  Http://www.a

问：对于多通道串行ADC,如果每个通道要采集的信号频率不同，怎样设定各个通道的信号采集率？
答： Normal use the maxim sample rate for all the channel. AD7490 (16 channel 12bit) has a sequency in side, will automatically change from one channel to another.
If different, it"s much difficult to control.

问：如果要扩展动态范围，是否可以采取小信号放大后再进行ADC量化，对于这个过程中的模拟电路有什么要求（例如时延和相移，以及失真等）？多片高速ADC的硬件实现上的布线原则是什么？怎样在实际中确保相互间产生最小的影响？高速ADC可能功耗比较大，对于散热的要求是什么？对工作环境的要求？
答： Yes, you can choose ADC with PGA, which means you can have different input range, then the dymanic range of ADC can be improved. For other actual design questions, below is a link to a good design guide of high speed ADC from ADI: http://www.analog.com/tec

问：7.对于咱公司的大部分sigma_delta ADC,梳妆滤波器、半带滤波器及FIR低通滤波器在各级一般是如何先后安排的？半带滤波器在抽取时会有少量的混叠，影响大吗？使用中只是不用作最后一级就可以了？FIR滤波器
的纹波系数一般是百分之几？
答： AD7730/AD7730L SIGMA-DELTA MODULATOR
The first stage filter is a low-pass, sinc3 or (sinx/x)3 filter whose primary function is to remove the quantization noise introduced at the modulator.
The second can run Normal FIR Operation.
SINC3 will ha

问：在开关电源的设计过程中，运用I2C接受外部控制信号来调整开关电源的输出电压。在这种情况下如何正确选择合适的ADC？并且应关注哪些重要的参数？
答： This application should use DAC here. The INL/DNL and output stage (current or voltage) are you considerations.