AD9257 AGND circuit

There are three GND below in our system.

DGND

AGND

GND for the image sensor

(image sensor is CMOS with analog output)

Connection of GND is shown below.

Image sensor GND---AGND---DGND

ADC will receive the signal from the sensor.

Does GND of AD9257 better connected to either AGND or image sensorGND?

Thanks,

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  • 0
    •  Analog Employees 
    on Dec 5, 2014 10:55 AM over 6 years ago

    Hi Tak-san,

    Just from the fact that the sensor output goes to the ADC, there is advantage to the ADC sharing that ground, but I think more information is needed.

    You mention "Image sensor GND---AGND---DGND". How are the different ground domains connected to each other (vias, traces, jumpers, isolated)? Are they split ground domains on the same layer? The image sensor GND is obviously for the image sensor. What other ADC related devices share ground with the image sensor? What devices related to the ADC are on the other grounds?

    On our evaluation boards we normally have one common ground so managing current return paths is not so complicated.

    Thanks,

    Doug

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  • 0
    •  Analog Employees 
    on Dec 5, 2014 10:55 AM over 6 years ago

    Hi Tak-san,

    Just from the fact that the sensor output goes to the ADC, there is advantage to the ADC sharing that ground, but I think more information is needed.

    You mention "Image sensor GND---AGND---DGND". How are the different ground domains connected to each other (vias, traces, jumpers, isolated)? Are they split ground domains on the same layer? The image sensor GND is obviously for the image sensor. What other ADC related devices share ground with the image sensor? What devices related to the ADC are on the other grounds?

    On our evaluation boards we normally have one common ground so managing current return paths is not so complicated.

    Thanks,

    Doug

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