Efficient approximation of the time domain response of lossy coupled transmission line trees

A new technique for rapidly estimating the transient response of lossy transmission line interconnect structures is introduced. The new approach, Reciprocal Expansion (REX), is similar to Asymptotic Waveform Evaluation (AWE) in that it approximates the interconnect by a low-order system. However, unlike AWE, REX expands the reciprocal of the transfer function as a Taylor series. REX has been extended to handle distributed elements directly, compute crosstalk between coupled trees, and account for frequency-dependent effects. Experimental results demonstrate that for critical underdamped interconnects, REX provides better accuracy than AWE