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AD5933 for impedance monitoring but maybe reaction exists

Question asked by on Jul 24, 2012
Latest reply on Jul 26, 2012 by

Hi all,


We are using the AD5933 for fast disease diagnosis (, but after I compared the results acquired using ad5933 with the ones by Impedance Analyzer (Agilent 4294a), I found they were different. So I am thinking maybe there was reaction caused by DC component in the process.


The paper from AD ( presented one ac coupled circuit, but I would like to know if my design will work first, because I have engraved the traces already.


Simply put, I added the Vout of AD5933 with a variable DC from an MCU using AD8641, this sum was connected to a switch/MUX while the Vin of AD5933 was also connected to this switch. After the voltage was stable (~ms), the switch will open and the samples will be stimulated by the voltage (Please take a look at the schematic). Will this work? Thank you so much!


And I also have some questions:

I will power the whole system through USB port (from a computer or a battery), is the power stable according to your experiences?

I am designing a multi-channel edition of this one, and I chose AD5932 as a signal generator instead of AD5933 (in the single channel one, the AD5933 acts as both signal generator and impedance analyzer). Will similar circuit suit for AD5932? The reaseon I use AD5932 is that it is cheaper and I observed that the waveform from AD5932 is tidier than AD5933.


Thank you so much for this, I deeply appreciate your help.



消息编辑者为:Xiaozhu Liu