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Bipolar supply for OPA1632

Jean-Paul Louis
Prodigy 50 points
Other Parts Discussed in Thread: OPA1632

I want to use OPA1632 to drive a 24 bits, 192 kSps ADC that has 5V supply. So I will have an offset od 2.5V at the input of the ADC.

So instead of using +/- 12V, I would like to shift the power supply of the OPA to +10V and -5V which should provide symetrical swing.

Will that be good for the ensemble OPA1632 + ADC?

  • 0
    TI__Genius 13335 points

    Hello,

    What ADC are you using? What is the full scale input voltage to the ADC? If the ADC is only being supplied at 5V and ground, you run the risk of exceeding the max voltage of the input pins.Other than that, the OPA1632 can operate on -5V and +10V and should be able to provide the full range for the data converter.

    Regards,
    Luke Lapointe
    High Speed Amplifiers

  • 0 in reply to Luke LaPointe
    Prodigy 50 points

    Hello Luke,

    Thanks for your answer. The analog part of the ADC (AK5394) is powered 0v to +5V, The signal is converted at a rate of 192 ksps and 24 bit in an I/Q mode (2 channels).

    My idea is to have no DC offset in the amplifier by modifying the supply, and creating a virtual ground at +2.5V which is the midpoint of the ADC..

    Also the fully differential structure allow noise floor to be lower, so narrow-band signals can be extracted from the 96 kHz spectrum.

    Regards,

    Jean-Paul Louis

  • 0 in reply to Jean-Paul Louis
    TI__Genius 13335 points

    Jean-Paul,

    Your idea is correct. The output common-mode voltage of the OPA1632 will be set either by applying a voltage to the Vocm pin, or it will be set to mid supply if left floating. In this case, if Vs-=-5V and Vs+=10V, the midsupply voltage will be 2.5V and your output will be centered around 2.5V.

    Regards,
    Luke