In extreme cases Printed Circuit Boards (PCB)-generated noise has resulted in equipment failure of commercial radiated emission requirements with shielded cables connected to a PCB metal faceplate, which in turn was connected to a shielded enclosure. The major source of radiation from PCBs and cables is not differential-mode current but common-mode current, for, depending on the geometry, the radiation due to several microamps of common-mode current can be as high as several milliamps of D/M current. The microstrip configuration is often the most convenient and due to the elimination of signal and power return tracks can reduce the number of layers in the PCB. In a typical complex PCB layout, a number of clock and data lines are routed around the board to which a number of ICs are connected. At low frequency, the current on an electrically short PCB layout is determined by the load impedance.