AD9218

Hi,

I m designing a new circuit based on AD9218 ADC and BF537 via PPI interface.

I have some questions about the ADC Vref and input range.

     Firstly, i wonder what is the effect of Vref to the input voltage range. My target is sampling 0V to 2V voltage volue by using 2V p-p configuration. Do i   need to use 2V external Vref to be able to work on this range or is it possible to sample 2V with 1,25V internal voltage reference output?

     Secondly, i did not exactly understand offset binary output. Could you please give me some example voltaj output values?

Third, My real input voltage is changing from 4V to 7V peak. I need to decrease this voltage levels to 2V but without using inverting op-amp. Do you have any suggestion a part from voltage diveder?

Regards,

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  • 0
    •  Analog Employees 
    on Aug 14, 2014 1:03 AM

    Hi,

    The primary front-end configuration difference is the AD9218 Analog Input Common Mode is internally self-biased, whereas with the AD9215 the Ain CM is not internally self-biased. You have to establish the Ain CM externally in your AD9215 configuration. The AD9215 datasheet provides several front-end configuration examples (see pgs 14-15, & 18-32) that include both transformer coupled and active differential driver amplifier front-end options.

    Best Regards,

    Tony M

Reply
  • 0
    •  Analog Employees 
    on Aug 14, 2014 1:03 AM

    Hi,

    The primary front-end configuration difference is the AD9218 Analog Input Common Mode is internally self-biased, whereas with the AD9215 the Ain CM is not internally self-biased. You have to establish the Ain CM externally in your AD9215 configuration. The AD9215 datasheet provides several front-end configuration examples (see pgs 14-15, & 18-32) that include both transformer coupled and active differential driver amplifier front-end options.

    Best Regards,

    Tony M

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