i am using ADuCM350EBZ Evaluation board Development kit for impedance measurement and i used IAR workbench for programming but in 4 wire configuration i am not getting accurate phase result can any one guide me what i do for getting accurate phase result . 

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    •  Analog Employees 
    on Oct 16, 2018 7:00 AM in reply to aitzaz


    The results shown there are using 500 Hz and 5 kHz. What board are you using? Did you use the same configuration at the one shown on figure 2?


  • i am using "4 wire Bio configuration 2" daughter board ,and yes my configuration and schematic is same as shown  in figure 2

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    •  Analog Employees 
    on Nov 16, 2018 12:01 AM in reply to aitzaz


    There is a lot of possible reasons about why the phase measurement is not good in their setup.

    Typically, due to long wires, shielded cables, layout with ground planes and long tracks, … what you have is a parasitic capacitor in parallel with your unknown impedance. The effect of that parasitic capacitor in your magnitude can be negligible. However, it can be observable in the phase measurement. In order to know if that is your problem, what you can do is a sweep in frequency. If the phase error increases if you increase the excitation frequency, the problem is you have a parasitic capacitor in parallel with your unknown impedance.

    If that is the case. There are several ways to solve it in function of the root of the problem. You can change your layout, use very short cables…, or you can do what an impedance analyzer does. You can do a calibration of your entire system. You do an “open circuit” measurement and a “short-circuit” measurement and you use that information to find out which are the parasitic components you have in serial and in parallel with your unknown impedance. It is complicated but it can be the only solution if you cannot change your layout or your cables