That is to say, they {TAIL ~ all} contain multiple current switches that are controlled to add charge to or remove {HEAD ~ charge} from a downstream circuit, which as a consequence generates an appropriate output voltage to control the VCO 16 and to move the PLL toward a phase locked state 
That is to say , they { TAIL ~ all } contain multiple current switches that are controlled to add charge to or remove { HEAD ~ charge } from a downstream circuit , which as a consequence generates an appropriate output voltage to control the VCO 16 and to move the PLL toward a phase locked state
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH OTH OTH