A termination structure for mating a cable connector to a circuit board includes a plurality of associated sets of terminals, each terminal set including a pair of differential signal terminals and a ground reference terminal. Each associated set of terminals is arranged in triangular pattern through the connector in order to reduce the impedance through the connector, and the sets are fixed within modules or blocks that are engageable together to form a connector housing. The housing modules permit adjacent associated terminal sets to be easily inverted so that the ground reference terminals of alternating associated terminal sets are located along one row of the connector along with signal terminals of intervening terminal sets, while the ground reference terminals of intervening terminal sets are located along a second row of the connector, along with the signal terminals of alternating associated terminal sets.