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