The SSN (Simultaneous Switching Noise) caused by parasitic inductance of low cost QFP (Quad Flat Package) package limits the DDR (Double Date Rate) interface data transfer rate of STB (Set Top Box) chip.This paper discusses the video data interdependency and DDR bus bit interchangeability

and proposes a bit-rearrangement method to reduce SSN of DDR interface.The video data used in STB chip has strong correlation in two space dimensions.Logic bits of DDR bus are physically interlaced according to specific algorithm during layout design phase

which makes spatial distribution of DDR output drive current more balanced.The balanced distribution decreases average current running through each pair of power/ground pin and reduces SSN accordingly.This method is applied in a HDTV (High Definition TeleVision) chip on TSMC(Taiwan Semiconductor Manufacturing Company) 55nm process.The DDR data transfer rate of the test chip in QFP package attains 1066Mbps.