With technology scaling into nanometer regime

VLSI chips become much more complex and suffer from rampant process variations.Therefore

statistical methods are replacing deterministic counterparts for power/ground(P/G) grid analysis and efficient local analysis methods are badly needed to reduce the analysis complexity.A novel single-node Successive Over Relaxation (SN-SOR) method is proposed to efficiently solve correlated resistor vectors a

nd then to directly compute voltage variations for question nodes of large IR droop.Compared with traditional global SOR methods

the SN-SOR method shows following advantages.First one is locality.Because only one stimuli is located at the question node

q

to compute the correlated resistor vector

R

q

SN-SOR relaxes nodes from

q

to its surround nodes as wave transmission and the wave stops at some nodes whose IR droop is less than one assigned little value.Second one is efficiency.SN-SOR only relaxes small parts of nodes in P/G circuits but also needs slightly less relaxation reiterations.Third one is low memory complexity.Among

R

q

SN-SOR only needs some strong correlated resistors and less weak resistors of typical nodes to compute the voltage variation.Experiments show SN-SOR is 20 times faster than global SOR methods with only 0.38% accuracy loss.