 if the half rate clock signal is sampled at a first state, selecting {HEAD ~ the quadrature} of the half rate clock signal or, if the half rate clock signal is sampled at a second state, selecting a digital complement of {TAIL ~ the quadrature} of the half rate clock signal; and 
if the half rate clock signal is sampled at a first state , selecting { HEAD ~ the quadrature } of the half rate clock signal or , if the half rate clock signal is sampled at a second state , selecting a digital complement of { TAIL ~ the quadrature } of the half rate clock signal ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH