AFE4404: the waveform drift issue

Cickey Xu

Part Number: AFE4404

Dear TI partner,

My customer select AFE4404 to design blood oxygen measurement product.now they had design test board by themselves.

now they catch the ADC output data and make simulation waveform,find the waveform drift very seriously. can you help analysis the reason?such as noise or layout or other reason?

below is the schematic and software and test waveform.for your reference.

part schematic

over 2 years ago

0 Cickey Xu over 2 years ago

Intellectual 656 points

PPG-02-2021_6_8.txtadd the test data.

0 Praveen Aroul over 2 years ago in reply to Cickey Xu

TI__Mastermind 49176 points

Hello Cickey,

Baseline drift of the signal can be caused by respiratory rate, muscle tremor and physiological changes within the body as a response to various stimuli.
In particular there is no parameter in the AFE to stop this, but it can be taken care in the algorithm. Easiest way to remove this effect is to use DC removal filter in the algorithm.