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ADC32J45: ADC32J45 Input Questions.(Single-End)

HENRY JUNG
Expert 2030 points
Part Number: ADC32J45

Dears.

We are in the circuit design of ADC32J45.

We need a guide to design the input of the ADC32J45 as single-ended.

We are need to Balun and Impedance guide information.

Why are there two Baluns in EVM?

Can not you just use one Balun?

Thank you.

  • 0
    TI__Genius 12780 points

    Hi Henry,

    The short answer is that there is a second transformer in order to correct the error that is introduced by the first transformer. Below is a picture of the analog input for the ADC32J45EVM.

    Using a transformer introduces a small phase imbalance into the input signal which negatively effects HD2 (second harmonic). In order to correct the phase imbalance introduced by the first transformer, a second transformer (identical part number/manufacturer) is placed directly after; however, its orientation is flipped and rotated.

    You could use one transformer, but you may notice HD2 is a little larger.

    Regards,

    Dan

  • 0 in reply to dBrock
    Expert 2030 points

    Dear.Daniel

    What happens to the Balun and Impedance design information when I type in high frequency single-end(JP port)?

    thank you

  • 0 in reply to HENRY JUNG
    TI__Genius 12780 points

    Hi Henry,

    I'm not certain as to exactly what the question is, but there are some passive components (L and R) added in the high frequency design to optimize the frequency response of the analog input network. Here is another schematic of a preferred analog input design from the datasheet.

    I hope that answered your question.

    Regards,

    Dan