Characteristic Impedance Extraction Using Calibration Comparison

A robust line impedance identification method is presented. It determines the characteristic impedance of on-wafer TLR standards measured after an initial off-wafer LRM or TLR calibration. The only assumption made is that the obtained trans-wafer error boxes are a cascade of a symmetric probe related disturbance and a change in reference impedance. The proposed method yields an unbiased estimate of the complex characteristic impedance. Results from coplanar lines on a high resistivity silicon substrate support the made assumption.