Issue link: https://iconnect007.uberflip.com/i/1540184
10 DESIGN007 MAGAZINE I OCTOBER 2025 How does an engineer know that the return path is where they expect? It can be expen- sive to wait until a design is com- plete, like the design in Figure 2, to see if crosstalk and radiation from the return currents are caus- ing EMI/EMC test failures. How does the engineer know if the power delivery network is imped- ance-matched to the load? Multi- ple resonances caused by poor F i g u re 2 : P i c ote st S 5 0 d e m o b o a rd fo r c ro s st a l k a n d E M I . ( C o u r te sy of P i c ote st a n d S i g n a l Ed g e S o l u t i o n s ³ ) ▼ impedance matching can result in tough-to-troubleshoot field fail- ures from rogue voltage waves. Engineers in the 1990s coined the term power integrity to describe the difficult challenge of delivering low noise quiet power to a high-speed digital load 2 . AI and cloud-compute, with their insane thousands of amps at sub- 1-volt power rails, are driving the target impedance into the micro- ohms. Even the shortest PCB interconnect routing can have micro-ohms of impedance that can impact the power integrity of F i g u re 3 : S i m u l ato rs m a ke i t p o s s i b l e to l o o k at vo l t a g e r i p p l e o n t h e p owe r ra i l vs . t h e g ro u n d ret u r n n et . T h e p owe r ra i l r i p p l e i s ex p e cte d to b e m u c h l a rg e r o n t h e a g g re s s o r p owe r ra i l , b u t i t c a n st i l l c ro s st a l k a s i g n i f i c a nt vo l t a g e r i p p l e o nto t h e v i ct i m p owe r ra i l a n d c re ate a g ro u n d b o u n c e of vo l t a g e o n t h e s h a re d g ro u n d n et . ▼