Overview

As VLSI technology advances with decreasing feature size as well as increasing operating frequency, inductive effects of on-chip interconnects become increasingly significant in terms of delay variations, degradation of signal integrity, and aggravation of signal crosstalk [72, 116]. Since inductance is defined with respect to the closed current loop, the loop-inductance extraction needs to specify simultaneously both the signal-net current and its returned current. To avoid the difficulty of determining the path of the returned current, the partial element equivalent circuit (PEEC) model [101] can be used, where each conductor forms a virtual loop with infinity and the partial inductance is extracted.

To model inductive interconnects accurately in the high frequency region, RLCM (M here stands for mutual inductance) networks under the PEEC formulation are generated from discretized conductors by volume decomposition according to the skin-depth and longitudinal segmentation according to the wavelength at the maximum operating frequency. The extraction based on this approach [59, 83, 84] has high accuracy but typically results in a huge RLCM network with densely coupled partial inductance matrix L. A dense inductively coupled network sacrifices the sparsity of the circuit matrix and slows down the circuit simulation or makes the simulation infeasible. Because the primary complexity is a result of the dense inductive coupling, efficient yet accurate inductance sparsification becomes a need for extraction and simulation of inductive interconnects in the high-speed circuit design.

Because the partial inductance matrix in the PEEC model is not diagonally dominant, simply truncating off-diagonal elements...