LT6600-10 : Chebyshev filter and Ripple Parameter

Hello,
I have questions on the choice of the  LT6600-10 component.
The function to be realized is "Single-to-Differential Input ADC driver" . The signal (0.5V-2.5V =2V p-p) in entrance of the driver has a bandwidth of 10 MHz.
The output signal from the LT6600-10 differential driver is sent to an ADC = LTC1475-12. This ADC component  makes an oversampling (x12) of the signal which is sent towards a FPGA (with décimator filter ..).
The component LT6600-10 integrates a Chebyshev anti-aliasing filter (4th Order Lowpass Filter with 10MHz Cutoff). My question concerns the ripple parameter of the filter.
This ripple must be low in the 0-10 MHz passband because of the precision required for our application (Total = 0.5 % Max with PVT variations).
Problem: 
- The datasheet indicates that the filter is flat in the passband (the  Amplitude Response curve for 5V is flat, and passband gain curve also). 
- The datasheet (ELECTRICAL CHARACTERISTICS) also indicates an ripple (0.5dB for 0-260 kHz, 1dB for 260kHz-8MHz, 1.7dB for 260kHz-10MHz). Normally this information is the good one !
This ripple is normal for a Chebyshev filter (type 1) but it is too important for our application: The precision in amplitude is insufficient. Is another integrated solution (driver + ialiasing filter = 2-4th Order Lowpass Filter with 10MHz Fc) possible ?

Best regards,

Philippe

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  • 0
    •  Analog Employees 
    on Sep 13, 2018 9:12 AM

    Hi Philippe,

    You can use LTC6601-1 a low noise, 0.5% tolerance, 5MHz to 28MHz, Pin Configurable Filter/ADC Driver.

    Attached below will be your configuration and the expected AC response with the bandwidth of 10MHz.

    Let me know if you have clarifications.

    Best Regards,
    Goz

Reply
  • 0
    •  Analog Employees 
    on Sep 13, 2018 9:12 AM

    Hi Philippe,

    You can use LTC6601-1 a low noise, 0.5% tolerance, 5MHz to 28MHz, Pin Configurable Filter/ADC Driver.

    Attached below will be your configuration and the expected AC response with the bandwidth of 10MHz.

    Let me know if you have clarifications.

    Best Regards,
    Goz

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