AD8039 noise issue

In this project, we used Linear's high speed ADC LTC2175, LT6409(SE~Difference) as the driver. AD8039 as the first level amplifier and follower. Signal input Range: ±0.5V~±5V (i.e. Gain: 1~10); Input Freq: DC~60 MHz; When the input signal of AD8039 connected to GND, the noise is about 20mv for ADC getting. But if put off AD8039, just connecting the input signal of LTC6409 to ground, the noise is 3.5mv, but seems AD8039 no owns so bad CMRR, would you like help give some suggestion on that. thanks in advance

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    •  Analog Employees 
    on Aug 2, 2018 3:21 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

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    EZ Admin
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    •  Analog Employees 
    on Aug 2, 2018 3:21 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin
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