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34 DESIGN007 MAGAZINE I OCTOBER 2025 Z-Target Today's software tools, such as the HyperLynx PDN Decoupling Optimizer, employ two distinct but complementary approaches. The first, synthesis, provides a quick iterative process following estab- lished best practices. This approach is particularly valuable for initial optimization and can rapidly iden- tify potential improvements in the design. The second approach utilizes genetic algorithms for more sophisticated optimization. This method begins with an S-parameter model of the PCB PDN, in this case, a 173-port S-parameter model, where Port 1 represents the Versal device pins with the package model connected in parallel, serving as the obser- vation point for impedance analysis. The remaining ports correspond to the 172 potential decoupling capacitor mounting locations on the board. The genetic algorithm considers multiple vari- ables simultaneously, including: • Capacitor selection from available library components • Optimal placement in mounting locations • Target impedance requirements across the frequency range • Cost constraints and component availability • Capacitor package size and assembly considerations Real-World Results The optimization process yielded remarkable improvements in both performance and cost effi- ciency. The baseline design, while effective, used 172 capacitors across seven distinct part numbers. Through optimization, multiple alternative solutions emerged, each offering unique advantages. Two solutions stood out, as shown in Figure 3. The first optimized solution reduced the capacitor count to 90 while decreasing part number variet- ies to six. This configuration achieved a 2.24% cost reduction while meeting all performance require- ments, though with minimal margin. The PDN imped- ance profile touched the Z-Target requirement line at specific frequencies (2.5 MHz and 13.5 MHz) but remained within specifications up to 15 MHz. To further explore design alternatives and poten- tial improvements, a second optimization analysis was conducted, this time incorporating an addi- tional 5% performance margin requirement. This F i g u re 3 : P D N i m p e d a n c e p l ot of P C B/ P KG b a s e l i n e (g re e n ) , o pt i m i ze r r u n 1 ( m a g e nt a ) , a n d o pt i m i ze r r u n 2 ( p u r p l e) . ▼