The second synthesizer synthesizes the second order intermodulation component of the first sub path and {HEAD ~ the input signal} of the second sub path to generate {TAIL ~ a synthesizing signal} 
The second synthesizer synthesizes the second order intermodulation component of the first sub path and { HEAD ~ the input signal } of the second sub path to generate { TAIL ~ a synthesizing signal }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL