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Original question:

PCM4201: DC Coupled

PCM4201: PCM4201: DC coupled?

Pablo Liberman1
Prodigy 70 points
Part Number: PCM4201
Other Parts Discussed in Thread: ADS1271, , THS4551

Hi,

I was using ADS1271 which offers a good DC and AC performance.

At the moment, the part is out of stock, so I'm considering replacing it with a PCM4201.

My application needs that a sensor is DC coupled to measure its bias, in addition to AC.

The sensor bias could be calibrated for each device, so the offset error (if any) should be corrected.

¿Is it possible to connect the input directly without a DC blocking capacitor?

¿Is the DC offset the same for each part, so it can be corrected?

¿is the DC response linear within the range?

Thank you,

Pablo

  • 0
    TI__Mastermind 23030 points

    Please refer to the above circuit that is a part of the datasheet. In this circuit the differential inputs are both provided with a DC Bias of 2.5v. An AC Signal acts differential increases the level on 1input while simultaneously reducing the level on the other.

    i don't know the nature of your sensor but you  could add an offset to the DC Level such that the net level is 2.5v. Then you coulld short

    out the coupling capacitor in this schematic and just connect the offset output to the input. 

  • 0 in reply to Sanjay Dixit
    Prodigy 70 points

    Hello Sanjay,

    Thank you for your answer. I think you are right.
    In fact, I been thinking about using the THS4551 diff amp which has a common mode voltage input (VOCM). I will connect it to a 2.5V voltage reference.
    I think that there aren't other problems besides the own converter's offset error, which can be corrected by software.

  • 0 in reply to Pablo Liberman1
    TI__Mastermind 23030 points

    Yes that is a possible implementation