Multiplexer for AD7641

Hello!

I'd like to use a MUX to extend the number of inputs for AD7641. I'm considering AD8180 and MAX393.

Do you think adding one of these will reduce the effective ADC resolution?

Are there other downsides? What should I look for when choosing a MUX? I think AD8180 is really fast and pretty low noise but offset and drift are higher then the amplifier I plan to use as ADC driver (AD8139).

Best regards,

Vitor.

  • Another doubt: if I understood correctly the datasheet glitch specification is equivalent to the maximum amplitude of an "impulse" the appears every time the output is multiplexed, right? does it deserve special consideration too?

  • 0
    •  Analog Employees 
    on Apr 1, 2021 8:51 PM

    Hello Vitor,

     

    To avoid significant reduction in ADC performance, the components used in your ADC front end (the multiplexer, ADC driver amplifier and RC kickback) must be selected to ensure that your input signal is properly settled. I am not sure of the specifics about your application, but at a minimum, each component in the ADC front end must have enough bandwidth and sufficient settling time to properly settle your inputs as well as meet the noise and other performance requirements for your application. For a more comprehensive overview regarding the design considerations and challenges of designing a multiplexed data acquisition system, I would recommend that your read this article: https://www.analog.com/en/analog-dialogue/articles/demystifying-data-acquisition-systems.html

    I am not sure what glitch specification you are referring to. If this is a question regarding the multiplexer data sheet, you will need to submit a question in the Switches/Multiplexer forum. 

     

    Best,

    Kiriaki