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ADS112C04: Bandwidth or GBWP of the integrated Programmable Gain Amplifier

Art Mecina
Genius 16585 points
Part Number: ADS112C04
Other Parts Discussed in Thread: OPA314, , ADS1220

Hello Guys,

Good day.

Our customer would like to know the Bandwidth or GBWP of the integrated Programmable Gain Amplifier inside the ADC. This data is useful for the FMEDA calculus associated to the final device (influence of spurious sensor oscillations on device failures). In this case, the GBWP represents the worst case (without any filter).

Thanks in advance!

Art

  • 0
    TI__Guru** 113765 points

    Hi Art,

    This is an unusual request.  We don't really specify the internal parameters of the PGA as the PGA is integrated with the ADC.  This isn't something we can measure.  So the design is based on simulation to meet specific parameters of the combination of devices.  I can say that the original PGA design was based on the OPA314, but it is unclear as to any changes or enhancements that may have been made to optimize the PGA to the ADC.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    TI__Genius 16585 points

    Hello Bob,

    Thanks for looking into this. The customer understand that the value they seek is difficult to achieve. If instead they consider the ADC device entirely, is it possible to know the passband of the AD Converter, from the input pin to the PGA, excluding sampling circuit and digital filter?

    Do the simulations we have on the device provide this data?

    Last question: without considering the exact value, the PGA bandwidth could be larger or tighter thad the OPA314 bandwidth?

    Thank you for your answer.

    Art

  • 0 in reply to Art Mecina
    TI__Guru** 113765 points

    Hi Art,

    I've discussed this with a number of people and we have never seen a request like this before and so we would like to get a better understanding of the importance of this specific parameter to the failure mode analysis.

    Normally I would expect to see this type of request with automotive qualified devices.  In some other cases it may be with respect to high reliability systems (aircraft control systems for one) but this usually is more in line with pin to pin shorts, or internal memory either as flash or internal fuses.

    The analog designer for the ADS112C04 is only familiar with a part of the design and not the PGA itself.  This comes from the ADS1220.  He said he has no idea what may be different in the ADS112C04 compared to the OPA314.

    The modulator rate is the actual sampling rate for the oversampled ADS112C04.  The modulator can run up to 512kHz in turbo mode if that is any help.  I really can't tell you anymore than that with respect to bandwidth.  For the device as a whole, the limitation will be based on the digital filter so you look at the filter response in the datasheet.

    Feel free to take this offline and contact me directly with additional information.

    Best regards,

    Bob B