The impedance across the first and second devices is compared to provide {HEAD ~ the respective bit} of {TAIL ~ the corresponding digital output word} 
of
The impedance across the first and second devices is compared to provide { HEAD ~ the respective bit } of { TAIL ~ the corresponding digital output word }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL