{HEAD ~ means} for comparing the SAR conversion time to {TAIL ~ a desired conversion time}; and 
{ HEAD ~ means } for comparing the SAR conversion time to { TAIL ~ a desired conversion time } ; and
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH