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Improving Vadc quality of AD5933

Category: Hardware
Product Number: AD5933

Good day everyone!

I am currently working on an analog front end for my AD5933 based BIA and I just recently found an unofficial LTSpice model for AD5933. (found here:  Use of AD5933 in LTspice for 4-wire Bioimpedance Measurement System 

I simulated the four-wire AFE configuration using the same LTSpice model but I cant help but notice some skewness of the internal Vadc's waveform. I could not tell if it is within tolerable range or if I have to worry especially in terms of accuracy. 

Also, correct me if I am mistaken, the voltage signal that I should expect to be received in the Vadc of the AD5933 should be within 0V to VDD with its center at VDD/2?

Thank you in advance!

Below is the waveform of the EVAL board:

While below is the four wire AFE config waveform:

The Vtx is a perfect sine wave while the Vrx skews at the lower half which effectively affects the Vadc's waveform.

Below is the LTSpice Schematic of the EVAL-AD5933 Board with corresponding parameters:

And below is the supposedly four-electrode configuration AFE:

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