{HEAD ~ a first low pass filter} coupled to said {TAIL ~ third signal} and having as an output a first filtered signal, 
{ HEAD ~ a first low pass filter } coupled to said { TAIL ~ third signal } and having as an output a first filtered signal ,
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH