Ansys SIwave-PI

Power Distribution Network & Automated Decoupling Capacitor Optimization

Ansys SIwave-PI includes SIwave-DC and adds AC analysis to accurately model power delivery networks and noise propagation on PCBs. SIwave-PI is ideal for analyzing power integrity distribution issues, automatically optimizing decoupling capacitor selection and placement — all while performing accurate voltage drop and power loss analyses.

  • Analysis
    • Includes SIwave-DC to analyze voltage drop and power losses
    • Automated capacitor decoupling analysis: SIwave-PI significantly improves engineering productivity by automating decoupling capacitor selection, placement and optimization. Using sophisticated genetic algorithms, SIwave-PI allows the specification of various constraints (capacitor price, total number of capacitors, desired network impedance, etc.) for consideration in its cost function. Accurate frequency-dependent S-parameter capacitor models are used during simulation. The impact of capacitor physical location and mounting technique is captured by the full-wave electromagnetic extraction engine.
    • Simple PI lumped analysis provides a quick calculation to determine capacitor values and placement. This solution ascertains the lumped-circuit equivalent of all capacitors on a board or package and can be used to develop best-candidate capacitors for a given design. It automatically determines the best type and number of capacitors for a frequency-dependent impedance mask.
    • AC PDN analysis to determine power domain impedance and admittance transfer functions over frequency
    • Effective loop inductance full-wave solution for each capacitor with regard to an observation port
    • Capacitor library browser identifying the effects of 20,000+ commonly used capacitors
    • Detection and location of plane resonances due to cavities within PCBs and packages
    • AC PDN chip–package–system analysis with Ansys RedHawk and Ansys Totem
    • PDN sensitivity analysis on passive components (capacitors, inductors and resistors) for help in identifying the impact of thousands of what-if variations
  • ECAD geometry import: translators to import ECAD geometry directly from Altium, Cadence, Mentor, Zuken, and GDSII and DXF file formats
  • Multiphysics: bidirectional links to Ansys Icepak and Ansys Mechanical for predicting temperature rise, thermal-induced stress and structural integrity

The Ansys SIwave Solver Technology technical brief offers a detailed explanation of AC SYZ analysis.


SIwave-PI presents several decoupling schemes (each consisting of a set of capacitors) that meet specified constraints. Engineers can browse the schemes and export a bill of materials (BoM). You can superimpose a 3-D bar graph on the layout to indicate loop inductance values. This provides an immediate, intuitive understanding of each capacitor’s effectiveness.