Why You Should Leave 100nF Decoupling Capacitors Behind

This article debunks the long-standing practice of using 100nF decoupling capacitors as a default. The author argues that this practice is outdated due to advancements in IC technology (faster switching speeds) and the availability of low-cost, high-capacitance MLCCs. The article dives deep into the physics of decoupling, explaining impedance, parasitic inductance and capacitance, and their impact on power delivery network (PDN) integrity. It advocates for using larger capacitors (1uF or 2.2uF) for better decoupling, reduced EMI, and improved PDN stability. The importance of capacitor package size and its influence on parasitic inductance are highlighted. The author suggests that the persistence of outdated practices stems from cognitive load reduction and historical cost considerations.