In general, {TAIL ~ transistors} used in {HEAD ~ circuitry} are designed to have this optimum concentration 
In general , { TAIL ~ transistors } used in { HEAD ~ circuitry } are designed to have this optimum concentration
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH