An electrical connector assembly has an insulative housing (2) defining a number of receiving spaces (24) and a number of contact modules (4) inserted in the receiving spaces. Each contact module comprises a first substrate (41) having a pair of substrate halves (411), and a pair of conductive units respectively mounted on corresponding substrate halves. The first substrate has a number of circuit traces formed thereon and one electronic component (415) disposed on one substrate half. The circuit traces is electrically connected with the pair of conductive units and the electronic component. The pair of conductive units share the electronic component commonly via the circuit traces.