means for supplying {TAIL ~ two kinds} of clock signals having the same frequency and a phase difference of {HEAD ~ 180 degrees}; and 
means for supplying { TAIL ~ two kinds } of clock signals having the same frequency and a phase difference of { HEAD ~ 180 degrees } ; and
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH