Power Integrity Analysis: Achieving Target impedance - Part 4

The most important part of the power design is to keep the target impedance of the power path which we call Power Distribution Network (PDN) to be below the target impedance such that chip functionality (chip to which power is connected) doesn't get effected. So, to achieve impedance below target impedance, we have to take few important measures.

• Decoupling capacitors help stabilize the PDN by reducing impedance at different frequencies. Select capacitors with appropriate values to cover a wide frequency range, considering their equivalent series resistance (ESR) and equivalent series inductance (ESL). Analyze using Hyper Lynx PI
• Minimize power plane inductance by using solid power and ground planes
• Shorten traces and use wide power distribution paths to reduce resistance and inductance
• Use simulation tools to model PDN impedance and verify compliance with the target impedance. This is where tools like Hyper Lynx PI analysis plays a role
• In PCB design, have power and ground planes as close as possible (meant thin dielectric spacing)