High-Accuracy Impedance Read-out Circuit for BIA-type Biomedical Sensors

An impedance read-out circuit with high accuracy implemented using a TSMC 0.18 um mixed-signal CMOS process for BIA-type (bio-electrical impedance analysis) sensors to detect biomarkers is proposed in this investigation. In addition to proposing the impedance estimation circuit, the associated analytic proof is also disclosed. Using a high-order approximation model and high noise rejection capability by the addition of OPAs (operational amplifiers), the proposed system demonstrates a solution with high accuracy in terms of the maximum impedance error ( < 6 %) and the least phase error ( < 3 ∘ ) in a frequency range from 1 kHz to 2 MHz.