Other Parts Discussed in Thread: ADS1282, OPA211, OPA210, THP210, OPA227, OPA1612
Hi experts,
I'm designing a high-precision measurement system that contains a low-noise and high-precision analog OPAMP front-end and an ADC.
My front-end circuit is all in single-end design and utilizes coaxial cable to transfer signals. But when I'm going to select an ADC chip, I found that almost all high-precision ADCs require or suggest using differential input type to achieve the best INL and SNR parameters specified in the datasheets. (As I understand, the differential structure can minimize the external interference and suppress the even-order harmonics and charge-injection of the switched-capacitors inside the chip and so on...)
Due to my lack of experience, I'm really confused about how to design the input circuit in precision measurement applications. (The ADC meant to be selected is ADS1281)
There are three methods as I immaturely thought:
- Connect the single-end OPAMP output (with mid-supply) directly to the differential input pair of ADS1281. (which mentioned in the datasheet, but is not recommended)
- Use a fully differential high-precision OPAMP to perform the transform from single-end front-end output to differential ADC input. (which may insert additional noise, and suffer from mismatches of the resistors in the differential OPAMP stage?)
- Select another high-resolution ADC that is optimized for single-end input? I don't even know if it exists.
I really need you experts' rich experiences to make the decision. If there are tutorials or technical articles that may contain the answer, please let me know!
Thank you very much!