仪器仪表用Σ ΔADC产品ADI

简介：

问：怎样能够解决小信号的干扰问题？
答： First is the choosing of devices with high performance (low offset, low bias current, low noise...), especially for front end devices like amplifier, or high precision ADC with good front end performance (like chopper amp, PGA, temperature compensation cir

问：TI（原BB）公司的一些sigma-delta ADC采用了所谓的resolution plus技术可以实现40KSPS时19bit有效分辨率，请问ADI有没有类似技术和产品
答： The BB parts require a long settling time because of the digital filter. The settling time is 5 output cycles, therefore the effective conversion time is only 8kSPS.
Also, the resolution quoted is "Effective" resolution rather than "Peak

问：If i have the 35m 10bit ADC, how to modificate it to get the 100m 10bit adc? thank you
答： You can use several such ADCs, and input it to the same processor. Get the clock 3X should be enough for you.

问：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： You can simulate it. To find out its frequency domain property. I think you can find it in textbooks. <<System and Signal>> for example.

问：在AD中，经常有数字地和模拟地，还有信号地，能否都统一接到电源地上？为什么？
答： Please refer to the datasheet and the link below,chapter 10:http://www.analog.com/technology/amplifiersLinear/training/sensorSignal.html

问：请问，在小信号放大之前怎样避免接地噪音的干扰呢？
答： 用差分输入仪表放大器（AD620，AD623，AD8821），且尽可能靠近传感器。放大后再传。称重中常这样。甚至用多个AD （AD7791），用数字传送，有时加ADuM1100 或 光耦隔离。

问：请问Σ ΔADC与普通的双积分型ADC除了在精度上，还有哪些优势与异同点，在什么时候能够与一般的逐次比较型ADC通用。谢谢！
答： 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.

问：我们正在开发的模块需要8路ADC输入及8路DAC输出，主要采集电阻及电流值，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： How many bits are you need?
AD7927 (8 ch 12bit SAR ADC) is very cheap.
AD7738 (8 CH 24bit S-D ADC) is very high accurate.
AD5308 (8 ch 8 bit DAC ) is very cheap.
AD5328 (8 ch 12 bit DAC) is also cheap.
You can also use ADUC831 (8ch 12b

问：如何选择器件，使放大器和ADC相匹配，使信噪比最高？
答： Most of the ADI Sigma-Delta ADCs include an on-chip low-noise PGA 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 simple RC filter required for anti-ali

问：然后VINN仍然接在AD73360的参考电压输出脚上(1.25V)上,VINP接如电压2.0V,此时采样AD的输出,得到数据是0X7E4A,而通过datasheet上P12的图来计算的话得到净输入0.75V时候AD输出应该是0X74CD;是AD73360的线性度不好需要分段线性化处理吗?还是其它原因?见过类似的问题吗?请指点,谢谢!
答： 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 simply re-calculate the step size.  You can contact our technical center for further assistance on