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TPS7A83A: Power supply for BIAS

Koji Ikeda
Expert 5725 points
Part Number: TPS7A83A
Other Parts Discussed in Thread: TPS7A57

Hello support team,

Customer ask BIAS power supply. Does BIAS power supply influence output noise? If yes, they need to use clean power supply like LDO or filtering. Do you have any data like PSRR from BIAS to OUT?

Thanks,

Koji Ikeda

  • +1
    TI__Genius 12511 points

    Hi Koji Ikeda, 

    Yes, the bias rail will have an impact upon the output noise of the LDO. Unfortunately for this device we do not have a PSRR Bias plot, but we do for the TPS7A57 to show the shape and general range of values for reference:

    The PSRR on the bias rail is significantly higher than on the input rail, but it is not infinite and that noise will be pushed onto the output. We do recommend creating the cleanest power rail for the BIAS as possible, but unless noise is a significant concern for the customer and ultra-low noise is what they want, then generally cleaning the rail would not be required. It is merely recommended by TI to supply the LDO with the cleanest power rail possible. It is not required to filter or place an LDO, that is the customers decision.

    Regards,

    John