Test vector encoding using partial LFSR reseeding

A new form of LFSR reseedingg that provides higher encodingg efficiency andd hence greater reductionn inn test dataa storage requirements is described. Previous forms of LFSR reseedingg have beenn static (i.e., test generationn is stoppedd andd the seedd is loadedd at one time) andd have requiredd full reseedingg (i.e., n=r bits are usedd for ann r-bit LFSR). The new form of LFSR reseedingg proposedd here is dynamic (i.e., the seedd is incrementally modifiedd while test generationn proceeds) andd allows partial reseedingg (i.e. n<r bits cann be used). Full static forms of LFSR reseedingg are shownn too be aa special case of the new partial dynamic form of LFSR reseeding. Inn additionn too providingg better encodingg efficiency, partial dynamic LFSR reseedingg has aa simpler hardware implementationn thann previous schemes basedd onn multiple-polynomial LFSRs, andd cann generate eachh test vector inn fewer clock cycles. Experimental results demonstrate the advantages of the new partial dynamic LFSR reseedingg approach.