Hai! Good day everyone.

I am freshman of analog design and currently develop the interfacing circuit for electrochemical sensor. In my design, it produces a dual output signal (VOA & VOB) from a single input. Currently I am investigate the noise performance by applying the transient noise at the input of my design and differentiate between the outputs.  the simple method to differentiate both of output signal included noise is use the differential amplifier since the diff_amp has ability to reject any common mode noise.

Unfortunately the output of diff_amp become a noisy(VOC). I notice that, it is because the inputs of diff_amp has different amplitude noise (see attachment). I am not sure whether my way to analysis the noise performance is correct or not? is it possible, the different mode noise exists between the input of diff_amp? if Yes, is there any method  to reject these noises without using a filter?

Thanks a lot

Best regard
adie