High frequency characteristics of MCM decoupling capacitors

Abstract

The increased frequency operation of CMOS microprocessors and other circuitry places severe demands on power distribution systems to supply stable, noise-free power. Particularly in MCMs, where short signal line lengths allow fast off-chip switching, improved decoupling capacitors are required for short-term charge storage to reduce dI/dt noise. This paper examines the relative parasitic contributions of off-chip connections, MCM power distribution planes, and decoupling capacitors, and the effect of these parasitics on power distribution integrity. It is shown that the effect of the inductances of chip-to-substrate interconnections can be minimized by using multiple interconnections and careful design both in a wirebond or in a flip chip environment. Similarly, the intrinsic inductance and resistance of power distribution planes, either solid, perforated, or the new IMPS (Interconnected Mesh Power System), is extremely low and does not determine the effectiveness of power distribution.