The present disclosure provide a probe card for wafer level testing. The probe card includes a space transformer having a power line, a ground line, and signal lines embedded therein, wherein the space transformer includes various conductive lines having a first pitch on a first surface and a second pitch on a second surface, the second pitch being substantially less than the first pitch; a printed circuit board configured approximate the first surface of the space transformer; and a power plane disposed on the first surface of the space transformer and patterned to couple the power line and the ground line of the space transformer to the printed circuit board.