{HEAD ~ The photodiodes} are integrally formed on {TAIL ~ a substrate} in close enough proximity so that the first and second photodiodes experience substantially the same environment 
are integrally formed on
{ HEAD ~ The photodiodes } are integrally formed on { TAIL ~ a substrate } in close enough proximity so that the first and second photodiodes experience substantially the same environment
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH