Hi,
It is stated that the ambient cancellation current on the AFE4490 is to eliminate the ambient light DC value. However, I am curious as to why this cannot also be used to reduce the pleth DC signal? Based on equation 2 (p. 30) of the datasheet, it seems that Icancel would also reduce the pleth signal. If the ADC value is low pass filtered, why can the DC component not be isolated to calculate the appropriate value of Icancel to reduce both the DC ambient and DC pleth? I don't understand why this cancellation scheme only applies to ambient light portion of signal.
Thank you!
