STM Journals Peer-reviewed research from Consortium e-Learning Network

Journal of VLSI Design Tools and Technology

Modelling of Skin Effect in On-Chip VLSI RLC Global Interconnect

  1. vikas maheshwari
  2. shilpi lavania
  3. rajib kar
  4. durbadal mandal
  5. A. K. Bhattacharjee

Abstract

This paper addresses one of the aspects of the high frequency effects, namely the skin effect. The basicproblem with skin effect is that it attenuates the high frequency components of a signal more than that ofthe low frequency components. Due to the increase in operating frequency and die sizes, RC models arebecoming insufficient for analysis of global VLSI interconnects. Accurate noise modelling for RLC lines isthus critical for timing and signal integrity analysis. Skin effect basically affects the resistance and also theinductance, which in turn affects the system integrity in particular and its response as a whole. The currentdistribution inside the conductor changes as frequency increases. These changes produced in theconductors are known as skin and proximity effect. Till now the skin effect has been neglected for themodelling the on-chip interconnects. But with the increase in frequency to the GHz range, the skin effecthas become prominent in performance parameter modelling. In this paper, firstly a crosstalk noise formulafor on chip VLSI interconnects has been proposed without considering the skin effect. The voltageresponse at the output node is analytically derived and then the skin effect on the line resistance isanalysed. From that an efficient and novel model is derived to estimate the crosstalk in the on-chipinterconnects. On-chip inductive effects are becoming predominant in deep submicron interconnects due toincreasing clock speeds; circuit complexity and decreasing interconnect lengths. Inductance causes noisein the signal waveforms, which can adversely affect the performance of the circuit and signal integrity. Inthis paper, we have also proposed a novel analytical model to find the impact of the skin effect on the noisein RLC interconnect without considering the skin effect on inductance because the value of the resistanceincreases dramatically compared to that of the value of inductance. In this work, the resistance variationdue to the skin effect is considered in two wire transmission line model. The correlation between the skineffect and the noise induced is also discussed. The simulation results justify the efficacy of the proposedcrosstalk noise model in the presence of skin effect.Keywords: On-Chip Interconnect, Skin- Effect, Crosstalk, RLC Segments, Coupling, VLSI
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