Effective Radii of On-Chip Decoupling Capacitors

Decoupling capacitors are widely used to manage power supply noise. A decoupling capacitor acts as a reservoir of charge, which is released when the power supply voltage at a particular current load drops below some tolerable level. Alternatively, decoupling capacitors are an effective way to reduce the impedance of power delivery systems operating at high frequencies [27]. Since the inductance scales slowly [207], the location of the decoupling capacitors significantly affects the design of the P/G network in high performance ICs such as microprocessors. With increasing frequencies, a distributed hierarchical system of decoupling capacitors placed on-chip is needed to effectively manage power supply noise [334].