Therefore this circuit produces a digital ramp signal with {HEAD ~ a slope} and frequency proportional to {TAIL ~ the numerical value} of the input digital word 
proportional to
Therefore this circuit produces a digital ramp signal with { HEAD ~ a slope } and frequency proportional to { TAIL ~ the numerical value } of the input digital word
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH