Characteristic impedance of asymmetrical differential traces: Closed-form relations for signal integrity analysis

Analytical models of high-speed interconnects are becoming increasingly important due to the large number and repetitive nature of signal integrity simulations. In this paper, closed-form relations are developed to calculate the characteristic impedance of differential traces routed on asymmetrical dual stripline layers. The solution is based on Schwartz-Christoffel transformation in combination with the partial capacitance concept. Numerical examples demonstrating the accuracy of the proposed method have been presented.