A clock generator generates two kinds of {HEAD ~ clock pulses} having opposite phases and {TAIL ~ the same frequency} 
A clock generator generates two kinds of { HEAD ~ clock pulses } having opposite phases and { TAIL ~ the same frequency }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL