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