the first circuit, filter and {HEAD ~ oscillator} constitute {TAIL ~ a phase locked loop} to synchronize the internal clock signal to the externally provided clock signal 
constitute
the first circuit , filter and { HEAD ~ oscillator } constitute { TAIL ~ a phase locked loop } to synchronize the internal clock signal to the externally provided clock signal
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH