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High Speed ADC with Bipolar Analog Input

Hello,

   I required an high speed ADC with bipolar analog input ranging from -V to +V. I was considering AD9042 but later on it came to my notice that it does not take in bipolar analog input. So, right now I am considering the following ADC's for the same purpose:

1. AD9246

2. AD9254

3. AD6645

      I do not have any information yet regarding whether these devices take in bipolar analog input or not. I request you to inform me whether any of these devices fulfills my requirement.

Thanks

Regards

Darshil Patel

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  • Hello Darshil,

    There are two analog inputs at ADC, named VIN+, VIN- that are in 180 degree difference. We can drive ADC either at the single-ended(using one of two inputs) or at differential (using both inputs). However, a differential inputs driving is suggested to achieve the optimum performance through high common-mode rejection and so on.   

    Analog input range is limited by internal circuit including supply voltage and it is specified in "Analog Input" section on datasheet.  It is mostly 1Vp-p or 2Vp-p differential (half of this voltage swing at each input) for most high speed ADCs( AD9246, AD9254 : 1Vp-p to 2Vp-p range, AD6645:2.2Vp-p). If there are beyond this full-scale level at Analog Inputs, we can't avoid performance degradation and there can be reliability issue some cases.

    There are some ADCs at sample rage for wide Vin range (for example, AD7626) but I don't see any high speed ADCs that allow -5V to +5V input range.

    The parts you are considering don't support 10Vp_p in -5V to +5V input range. You can do ADC product search by specifying parameters at the  link below and below is the screen shot as example.  

     

    http://www.analog.com/en/parametricsearch/10826#/p193=|3|12|14|16&p1746=40000000|26000000000&p3062=|1|6&p4913=1|8.192&sel=row12|row98|row117

    Thanks

    Tony

Reply
  • Hello Darshil,

    There are two analog inputs at ADC, named VIN+, VIN- that are in 180 degree difference. We can drive ADC either at the single-ended(using one of two inputs) or at differential (using both inputs). However, a differential inputs driving is suggested to achieve the optimum performance through high common-mode rejection and so on.   

    Analog input range is limited by internal circuit including supply voltage and it is specified in "Analog Input" section on datasheet.  It is mostly 1Vp-p or 2Vp-p differential (half of this voltage swing at each input) for most high speed ADCs( AD9246, AD9254 : 1Vp-p to 2Vp-p range, AD6645:2.2Vp-p). If there are beyond this full-scale level at Analog Inputs, we can't avoid performance degradation and there can be reliability issue some cases.

    There are some ADCs at sample rage for wide Vin range (for example, AD7626) but I don't see any high speed ADCs that allow -5V to +5V input range.

    The parts you are considering don't support 10Vp_p in -5V to +5V input range. You can do ADC product search by specifying parameters at the  link below and below is the screen shot as example.  

     

    http://www.analog.com/en/parametricsearch/10826#/p193=|3|12|14|16&p1746=40000000|26000000000&p3062=|1|6&p4913=1|8.192&sel=row12|row98|row117

    Thanks

    Tony

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