The first circuit uses the clock signal received at {HEAD ~ the first input node} to control {TAIL ~ the frequency} of the oscillator 
The first circuit uses the clock signal received at { HEAD ~ the first input node } to control { TAIL ~ the frequency } of the oscillator
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH