AD9246: Using Opamp

Document created by analog-archivist Employee on Feb 23, 2016
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Help me please concerning a "INPUT COMMON-MODE VOLTAGE" range of AD9246 and
its impact on the ADC performance: SNR and SFDR. 
In the AD9246 datasheet on page 15 the following is told: Setting the device
such that VCM = 0.55 * AVDD is recommended for optimum performance; however,
the device functions over a wider range with reasonable performance (see Figure
32). 
Unfortunately the given figure (on page 14 ) is limited by the value = 1.3V of
the INPUT COMMON-MODE VOLTAGE. 

 

Firstly, the SNR and SFDR will decrease ouside the the limits shown on figure
32 in the datasheet. We won't guarantee performance ouside this limit.

The input Commonn mode Voltage Range of the ADA4937-1 is 0.3V to 3.0 V ,
therefore the Vocm can be set to 1V. Unfortunately, the Vin of 2Vp-p is not
possible.

The ADC can handle an input Signal of 0V to 2V, with a Vocm of 1.0V.
Unfortunately, i do not have data on higher ADC distortion (1.5V to 1.7V).

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