AD5933 measuring low impedances

Hi all,

I am looking to measure impedances in the range of 100-10kOhm. As I understand it, this higher limit should be no problem but the lower limit might be, as the documentation mentions 1kOhm as the lower limit. Is there any way to circumvent this limitation?

  • If you use the evaluation board 100 Ohm and up should be manageable with the current circuitry. Brute force solution for much lower impedance would be to replace the AD8606 dual OPAMP on the board by an OPAMP with higher output current, for example, ADA815 or TCA0372 with 0.5A and 1A output current capacity and use lower value RFB. In practice it will likely require beefing up the power supply, taking care of heat dissipation by the high-current OPAMPs and prevent the impedance under test from frying.

    More intelligent approach would be to utilize some impedance converter, for example, a simple transformer, but is is difficult to suggest anything specific not knowing what your end application is.