An apparatus for controlling {HEAD ~ supply voltage} for {TAIL ~ a successive approximation register analog to digital converter} , comprising: 
An apparatus for controlling { HEAD ~ supply voltage } for { TAIL ~ a successive approximation register analog to digital converter } , comprising :
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH