The value of the output series resistance depends upon the selected output excitation range at Vout and will have a tolerance from device to device like all discrete resistors manufactured in a silicon fabrication process. Therefore, in order to accurately calibrate the AD5933 to measure small impedances, it is necessary to reduce the signal current by attenuating the excitation voltage sufficiently while accounting for the output series resistance value (Rout) in the Gain Factor calculation.

