A new method for measuring characteristic impedances of CMOS interconnect transmission lines

This paper proposes a new method for determining the broadband characteristic impedance of CMOS interconnect transmission lines using the measured S-parameters of a line, a serial resistor and a shunt resistor where the impedances of the resistors need not to know. The unknowns are evaluated by minimizing an objective function consisting of nonlinear equations regardless of the parasitic effects among the probe pads and the transmission lines. Contrasting with other methods, the proposed approach takes advantages of simple test keys without the reference line for comparison or additional dummy structures for de-embedding. The measured results for the microstrip lines built by the 0.18 µm 1P6M process are shown from 2 GHz to 60 GHz with comparisons of other measuring approaches.