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