a processing circuit that controls the current control signal according to {HEAD ~ the comparison output signal} to calibrate {TAIL ~ the driving current}, 
to calibrate
a processing circuit that controls the current control signal according to { HEAD ~ the comparison output signal } to calibrate { TAIL ~ the driving current } ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH