Simulating AD8333

Hello, My questions are actually basic. I am using AD8333 in my project for bioimpedance measurement. The main aim is to study the food quality using 4 electrode method (auto balancing bridge method). So I wanted to use AD8333 to extract real and imaginary parts of impedance. But I am not getting any proper waveform, its completely distorted. And I wanted to know what would be the relation between the amplitude of output voltage after AD8021 and the impedance value, I am facing some difficulties in understanding that from datasheet. I hope I can use this IC for my particular application. Moreover, I am simulating in Multisim, where I cannot find any LVDS driver so I have used another LNA for LO inputs. Will it be okay? And mainly, I need your help to know if I have made some mistakes with connections or if there are any errors you can rectify for me. Kindly guide me. In my simulation for now, I have used a simple RC parallel circuit to represent bioimpedance in food samples. I am also attaching the picture of the waveform I am getting. Sorry for the circuit being a little messy.

attachments.zip
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  • Hello,

    Thank you so much for your reply, it definitely helps. And yes with Multisim, sometimes I face convergence issues for some values. So I will definitely follow your suggestion and try to check for transient analysis details. I am using AD8333 as the other I/Q demodulators have RF input range starting from 50MHz or 400MHz and for my application, I needed an IC that starts from lower values. Plus, when I started simulation, initially the Spice model of AD8333 was not available. Should I send you or upload my Multisim file so that you can get better overview? So that I can atleast be sure if I have correctly connected AD8333.

    Regards,

    Hetashri

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  • Hello,

    Thank you so much for your reply, it definitely helps. And yes with Multisim, sometimes I face convergence issues for some values. So I will definitely follow your suggestion and try to check for transient analysis details. I am using AD8333 as the other I/Q demodulators have RF input range starting from 50MHz or 400MHz and for my application, I needed an IC that starts from lower values. Plus, when I started simulation, initially the Spice model of AD8333 was not available. Should I send you or upload my Multisim file so that you can get better overview? So that I can atleast be sure if I have correctly connected AD8333.

    Regards,

    Hetashri

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