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How to sense current difference using a precision ADC?

Category: Hardware
Product Number: LTC6363, AD4003

Hello, we have a position detector that generates Ia, Ib, and Ignd current outputs, where the common mode of Ia and Ib is 120 uA and the difference ranges from -100 uA to +100 uA. We require a small form factor and low bill of materials solutions to convert the current differences to digital bits, ideally ranging from 16 to 20 bits, while also monitoring the common mode on a test point.

  1. We are using OP27 as TIA amplifiers and would like to amplify 120 uA to Vref/2, could we connect the outputs of TIA amplifier directly to the RC SH circuit of AD4003? Is there a better alternative to OP27?

  2. Does ADI offer any solutions for measuring and converting current differences (in the scale of uA) to high-precision bits, while also meeting our requirements for small size and low bill of materials?

In short, can we sense a differential current input using a fully differential amplifier and direct fed to AD4003?

Best regards,

Benyuan



Sum up the questions we had.
[edited by: liubenyuan at 4:44 AM (GMT -4) on 10 Apr 2023]
Parents Reply Children
  • Thank you, I will use ADA4610 to convert the Ia, Ib to Va, Vb.

    The common mode of Ia and Ib is 120uA +- 10%, and the difference of Ia-Ib is in the range of [-100uA, +100uA]. I would like to use an differential ADC to sample the Va-Vb after two TIAs.

    My question is, could I simplify the ADC buffer circuit by using two amplifiers directly, that amplify 120uA to 2.048V reference voltage?

    Do I need a differential ADC driver (for example, LTC6363) that placed between Va, Vb and ADC (differential input)?