Electronic – How does the Bias Drive in TI ADS1299 help in noise reduction

adcbiasbiopotentialcommon-modetexas instruments

I'm bit of a noob in electronics so please pardon me if this question is too basic.

I would like to clearly understand how the signal from the bias drive electrode can help in noise reduction, reducing baseline drift and other artifacts.

As a user puts it in this forum page "This BIAS drive signal drives the patient with an inverted common-mode signal that can help reduce noise and 50/60Hz interference."

I'm not able to understand the above statement on how the inverted common-mode signal can help in noise reduction. If some can explain the intricacies behind this concept, that would be great!

Best Answer

The body acts as an antenna for 50Hz or 60Hz radiation. This can mess up low level signals and make it difficult to read out the ECG information. A bias drive (also called Driven Right Leg) takes a copy of the 50Hz or 60Hz radiation and drives the leg with a scaled, inverted version, effectively canceling it out. So, with a bias drive, the 50Hz or 60Hz interference appears both on signal and common, so you take the difference and it is canceled.

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