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