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