In addition, {TAIL ~ a subtractor} produces {HEAD ~ an error signal} by subtracting the output signal from the reference input signal 
In addition , { TAIL ~ a subtractor } produces { HEAD ~ an error signal } by subtracting the output signal from the reference input signal
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH