What input resistance for AD7960?

I would like to know what would be the maximum recommended resistances to place between an FDA and AD7960 inputs (R3 and R6 on the figure below). I would like to reduce the capacitor value to reduce power consumption of the LTC6363 and increase the resistances accordingly to keep cutoff frequency. I am thinking of 200R or 300R instead of 100R. The input signal is a amplitude modulated sine wave, 125kHz.

Thank you in advance for your inputs.

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    •  Analog Employees 
    on Oct 26, 2017 9:42 AM

    Hello Elder,

    If its okay I'd like to know  what's your end application? We have verified the recommended RC(33Ω, 56pF) filter that offers that optimum performance for both muxed and non-muxed use cases. Increasing R to 200 to 300 will certainly affect the THD performance, not so much SNR. However, I'd strongly recommend to verify the SNR/THD performance on the evaluation board for a given RC combination.

    regards,

    LLoben

     

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  • 0
    •  Analog Employees 
    on Oct 26, 2017 9:42 AM

    Hello Elder,

    If its okay I'd like to know  what's your end application? We have verified the recommended RC(33Ω, 56pF) filter that offers that optimum performance for both muxed and non-muxed use cases. Increasing R to 200 to 300 will certainly affect the THD performance, not so much SNR. However, I'd strongly recommend to verify the SNR/THD performance on the evaluation board for a given RC combination.

    regards,

    LLoben

     

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