Limitations of using AD8352 amplifier with AD9434 ADC?

Hi Everyone,

Are there any limitations of using the AD8352 amplifier with the AD9434 ADC? They are shown together in the ADC datasheet, but now the website for that part recommends a newer amplifier, the ADL5562. We need a 1GHz analog front end and will be sampling it at 500MHz. My question arises from the following line from the press release for the newer amplifier. Why do they say the AD8352 has a limit of 380MHz?

"The ADL5561 and ADL5562 are capable of maintaining performance while driving ADCs up to 500 MHz, exceeding the industry’s previous maximum of 380 MHz, set in 2005 by ADI’s AD8352 differential amplifier."

Thanks,

Ben

  • 0
    •  Analog Employees 
    on Aug 28, 2014 7:16 PM

    Hi,

    I moved this post to the Differential Amplifier space, someone here should be able to help.

    Regards,

    David

  • 0
    •  Analog Employees 
    on Sep 3, 2014 8:57 PM

    Hello Benjamin,

    I apologize for the delay in response to your original question. The AD8352 is said to have a limit of 380 MHz mainly because that is the frequency in which the harmonic distortion performance begins to degrade. I've attached a spreadsheet showing a comparison of the noise/distortion performance of the AD8352, ADL5561 and the ADL5562 differential amplifiers.

      

    After looking at the performance of all 3 drivers at 500 MHz, it is clear that the ADL5562 has the lowest distortion, lowest noise spectral density, and best IP3 at the stated test condition. Will your application be ac or dc-coupled?

    Best Regards,

    Joe Peralta

  • Thank you, that is an interesting table. Our application is AC-coupled, how does that affect the conclusion? This is for a time domain reflectometry application. We tend toward the AD8352 amplifier simply because the datasheet for the AD9434 ADC shows a reference design for the pair.

    Thank you!

    Ben

  • 0
    •  Analog Employees 
    on Sep 3, 2014 9:42 PM

    Hi Benjamin,

      

    In a dc-coupled application, the output common-mode voltage of the amplifier would have to fall in the range of the input common-mode voltage of the ADC. Since you're application is ac-coupled, this will not be an issue. The AD8352 will certainly be able to drive the AD9434 without any limitations. The output of many differential drivers is typically ac-coupled to allow for an optimal common-mode setting at the input of the ADC. Many amplifiers also tend to have a common-mode voltage pin which can equally shift the input and output common-mode voltages of the device. I hope this helps you with your selection.

    Best Regards,

    Joe

  • 0
    •  Analog Employees 
    on Aug 2, 2018 2:45 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