The method 15, {HEAD ~ the generation} of {TAIL ~ the tracking signal} is performed by operating two or more tracking cells coupled to the first tracking bit line 
The method 15 , { HEAD ~ the generation } of { TAIL ~ the tracking signal } is performed by operating two or more tracking cells coupled to the first tracking bit line
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH