ADS1262 - Can I get information for the INPUT-REFERRED NOISE SPECTRUM data at gain 32 (nV/root Hz) ?

Hi Sung ho,

Using the ADS1262 Design Calculator, you can divide the noise by the square root of the digital filter bandwidth and get the following information:

The noise spectral density will be fairly flat across the frequency range; however, the three fastest data rates have some additional noise in the higher frequency range due to the noise-shaping of the delta-sigma modulator, as seen by Figure 20 in the ADS1262 datasheet:

I hope that helps!

Best Regards,
Chris

Dear Chris,

Thank you for your kindness fast reply..

I have some question for the table you sent me.

Could you tell me the test condition of the noise performance table ?

* Using Internal reference  or external ?

* In the data sheet, the noise performance in the table were measured under the Unipolar 5 V condition.

 When I use bipolar voltage input (-2.5 ~2.5), I would like to know if noise performance is improved or degraded ?

If the condition is internal reference using, can I improve noise performance a little as using external low noise reference IC ?

Have a nice day.

Regards.

Hi Sung ho,

The noise performance data was measured with the ADC inputs shorted. In this configuration, reference noise is not seen in the output codes because reference noise is proportional to the input signal amplitude.

For more info on this topic, refer to the following blog post: 

For non-zero input signals, you will see additional noise coming from the reference... The ADS1262 Design Calculator has a "System Noise Estimator" calculation which shows the noise of the ADS1262 internal reference versus the input signal amplitude. The calculator also shows the estimated noise performance with an external REF5025 reference.

The REF5025's noise is about 1/2 that of the ADS1262's internal reference; therefore at 100% full-scale input,  the REF5025 can provide about 1 additional bit of resolution. However, for small input signals you might not see much of a difference.

Additionally, the noise of the ADS1262 was observed for both unipolar and bipolar supply configurations and the noise performance did not change. Therefore, the noise specifications will be valid for both cases.

Best Regards,
Chris