ADS1298: ADS1298

Star Xu

Part Number: ADS1298

I am studying on thermal noise analysis in ECG applications. Patient protection resistor is connected in both the leads. But during the final calculation only RMS noise of one resistor is considered. Dont we have to consider the noise contribution of other resistor on the negative line.

In page 5, When calculating the RMS value of protection resistor, root 2 is multiplied, does it account for the other resistor.

Waiting for your reply.

Thanks

Star

over 8 years ago

0 Alexander Smith over 8 years ago

TI__Guru 61362 points

Hello Star,

Thank you for your post.

Can you provide the document that you are referring to?

0 Star Xu over 8 years ago in reply to Alexander Smith

TI__Genius 9645 points

Hi Alex

Please kindly find the following link.

http://www.ti.com.cn/cn/lit/an/sbaa185/sbaa185.pdf

thanks

Star

0 Alexander Smith over 8 years ago in reply to Star Xu

TI__Guru 61362 points

Hello Star,

Thank you for providing the link to the thermal noise in ECG applications document.

Yes the thermal noise from the resistor in the negative line must be considered. Since thermal noise scales with resistance, you are correct when assuming that sqrt(2) accounts for the resistance in the negative line.

When performing the thermal noise calculation it is acceptable to either multiply R by 2 like below:

e^2 = sqrt(4kT2Rf)

Or simply multiply the whole calculation by sqrt(2):

e^2 = sqrt(4kTRf)*sqrt(2)

Hope this helps.

Data converters

Data converters forum

ADS1298: ADS1298