DesignCon 2012 Are Power Planes Necessary for High Speed Signaling?

The performance of a system depends heavily on the communication speed between integrated circuits, which is constrained by the power delivery networks (PDNs). The disruption between the power and ground planes based on the low target impedance concept induces return path discontinuities during data transitions, which create displacement current sources between the power and ground planes. These sources induce excessive power supply noise which can only be reduced by increasing the capacitance requirements through new technologies such as thin dielectrics, embedded capacitance, high frequency decoupling capacitors and other methods. The new PDN design proposed here using power transmission lines (PTLs) enables both power and signal transmission lines to be referenced to the same ground plane so that a continuous current path can be formed. Extensive simulations and measurements are shown using the PTL approach to demonstrate the enhanced signal integrity as compared to the currently practiced approaches.