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ADS52J65: ADC RF input impedance question

JK HAN
Prodigy 10 points
Part Number: ADS52J65

Tool/software:

Hello,

I'd like to inquire about the RF input port of the ADS52J65. I've thoroughly reviewed the data sheets provided by TI, but I couldn't find any information regarding the impedance of the RF input port.

Could you please provide the impedance of the AIN port on the ADS52J65? We plan to use signals in the 20-50MHz frequency range.

Thank you.

  • 0
    TI__Expert 4155 points

    Hi,

    Input equivalent circuit is mentioned in the datasheet in figure 61. You can simulate that at your frequency of interest to get the impedance. 

  • 0 in reply to Sachin H K
    Prodigy 10 points

    Hello,

    Thank you for your response.

    I have already tried applying the information from figure 61 in the datasheet. The calculated values seem to convert to several ohms. However, this calculation doesn't work without knowing the load on the IC side.

    Is there a reason why the impedance of the IC's input port is not separately specified? If it could be provided like other ICs' RF input impedances, it would greatly help in designing and save time.

    I appreciate your assistance.

    Best regards,

  • 0 in reply to JK HAN
    TI__Expert 4155 points

    This is unbuffered ADC . Datasheet mentions the equivalent input diagram. Here there are 2 switches S and SZ . I think you would be interested in impedance when S=1. So You have to make transistor SZ open. and S transistor should be replaced by corresponding Ron.

     This input impedance is varies with respect to frequency so there is no specific impedance mentioned in datasheet .