The Importance of Using Time Domain to Analyze the Effect of Decoupling Capacitor Performance on Printed Circuit Boards

摘要

This paper demonstrates the importance of using the time domain to properly analyze decoupling capacitor performance on printed circuit boards as well as ASIC packages, etc. Frequency domain analysis is too limited unless the phase information is used along with the magnitude information. The time domain analysis combines the magnitude and phase information to allow a more accurate analysis of decoupling capacitor distance, decoupling capacitor value, and the effects of connection inductance. The impact of connection inductance is extremely important and it needs to be included in any decoupling capacitor analysis, since this inductance can easily overshadow low plane impedance (by buried capacitance, etc) and make the Power Distribution Network (PDN) ineffective.