{HEAD ~ An adding unit} adds the reference signal to the filtered signal to generate {TAIL ~ an output signal} 
{ HEAD ~ An adding unit } adds the reference signal to the filtered signal to generate { TAIL ~ an output signal }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL