GND vs AGND Different question

[feveran]

Im working on the circuit given http://www.ti.com/lit/an/sbaa266/sbaa266.pdf
In the circuit a bias voltage is applied to the sensor's ref. pin just said in page 2, section 2 .
Now change ADC122S021 with Teensy.
AGND is not connected to the anywhere.
Is it correct?

 

[Theremingenieur]

The AGND is sometimes needed when using the internal ADCs of the Teensy. AGND is connected to GND on the Teensy board through a small inductor to decouple RF noise. But when using external ADCs and references, this doesn't change anything.

 

[feveran]

Maybe you didn't read my post. Im not using external ADC. Change question like this. What to do with AGND if I make analog input signal with voltage divider on Teensy's 3.3V pin between GND?

 

[Theremingenieur]

I followed the link which you posted above to understand what you want to achieve...

Now, that you do apparently not use an external ADC, you should try out. Depending on the source impedance and the selected analog read resolution, you might get better results with connecting the divider either to GND or AGND. Do a Series of readings in both variants and look at the results. Decide for the variant with less straying in the results.