Impedance of power distribution networks in TSV-based 3D-ICs

To estimate the simultaneous switching noise (SSN) on the three dimensional VDDQ power distribution network (3D VDDQ PDN) in a TSV-based GPU system, the PDN impedance (Z_PDN) and the pull up impedance (Z_pull-up) of the VDDQ PDN in the GPU system were first estimated and analyzed. The GPU system consisted of a GPU, quadruple-stacked DRAMs, a silicon interposer and an organic package. The impedance estimation method, based on a segmentation method and a balanced-transmission line method (Balanced-TLM), was used for the estimation of the PDN impedance and the pull-up impedance of the 3D VDDQ PDN, combining the models of the chip PDNs, S/G lines, P/G TSV pairs, and a package PDN. The PDN impedance and the pull up impedance were also analysed with respect to the variation in the number of the P/G TSV.