ANSYS SIwave Features

ANSYS SIwave software analyzes printed circuit boards (PCBs) and IC packages prevalent in modern electronic products. It provides predictive results in both time and frequency domains, resulting in virtual compliance of digital and analog systems.

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SIwave-DC SIwave-DC

Integrated & Automated DC I²R Reporting

ANSYS SIwave-DC targets DC analysis of low-voltage, high-current PCB and IC packages, enabling assessment of critical end-to-end voltage margins to ensure reliable power delivery. It allows users to perform pre- and post-layout what-if analyses for DC voltage drop, DC currents and DC power loss. This process ensures that power distribution networks (PDNs) can source the proper power to integrated circuits — checking that the PDN has the proper bump, ball and pin sizes as well as proper copper weighting to minimize losses — and identify areas of excess current, which can result in thermal hot spots, to reduce risk of field failure.

The SIwave-DC solver was developed specifically for planar ECAD geometries. The entire structure is discretized into a number of finite elements, and a variational technique (finite element method, or FEM) computes voltage and current distribution across an entire power delivery network. In general, the overall accuracy of an FEM-based solver depends on two factors: the accuracy with which a mesh can match design geometry and the accuracy of the numerical solution.

To minimize geometry discretization errors, triangular elements are used for modeling arbitrary package or board structures. Once an initial triangular mesh is generated with SIwave-DC, it is used as the input for the finite element solver to compute voltage distribution across the PDN for a given set of external sources and sinks. The accuracy of the numerical solution depends on the density and distribution of mesh elements as well as on the order of basis functions used within each mesh element. To control numerical solution accuracy in SIwave-DC, an h-type adaptive mesh refinement algorithm is used, similar to those employed in ANSYS HFSS and ANSYS Q3D Extractor. For a given mesh and given numerical solution for the mesh, the numerical error is computed within each mesh element, and the elements with the highest errors are selected for refinement. Mesh refinement splits these elements into smaller pieces. Once a new mesh is generated, the problem is solved again and the process repeats until the total numerical error is below the tolerance set by the user. This completely automated procedure, called automatic adaptive meshing, guarantees an optimal mesh (size and density distribution) and ensures an accurate solution with the fastest speed and lowest RAM utilization.

  • Analysis
    • DC voltage drop for all nets, including traces, ground and power
    • DC current hot-spot detection
    • Electromigration and warranty analysis
    • DC Power loss with thermal coupling to ANSYS Icepack
  • Automatic adaptive mesh refinement ensures highly accurate, predictive analyses for chip, packages, and printed circuit boards that include ECAD primitives, such as planes, traces, vias, bondwires, solderballs and solderbumps
  • Path resistance from power sources to chips
  • Enhanced accuracy due to chip-level modeling for static DC losses
  • Bidirectional coupling to ANSYS Icepak to calculate thermal losses
    • Automated reports for user-defined pass/fail criteria

 

Current and voltage distribution plots on VCC plane
  Path Resistance
Initial Mesh
Time & RAM Path Resistance
Final Path
Time & RAM
Voltage Source to CPU 1

17.236 mΩ

1 - Pass

11 seconds

6.7 MB

18.278 mΩ

17 seconds

8.1 MB

Voltage Source to CPU2

16.850 mΩ

1 - Pass

10 seconds

6.7 MB

17.870 mΩ

16 seconds

8.1 MB

Path resistance from VRM to different CPUs within PCB shown above: time and RAM required for automatically adaptive converged solution

SIwave-PI 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.

SIwave SIwave

End-to-End Signal Integrity Analysis

ANSYS SIwave combines SIwave-DC and SIwave-PI functionality and adds the robust ANSYS Nexxim time-domain circuit simulation engine. SIwave employs specialized full-wave finite element algorithms to compute resonances, reflections, inter-trace coupling, simultaneous switching noise, power/ground bounce, DC voltage/current distributions, near- and far-field radiation patterns on high-speed PCBs and complex IC packages. With SIwave, signal integrity engineers can easily import  ECAD geometry, extract GHz-accurate interconnect models for the IC, package and PCB, include transistor-level models of drivers and receivers, and run SSO analysis, impedance matching and power delivery system optimization. This solution includes common IBIS analyses such as power-aware IBIS and IBIS-AMI to provide virtual compliance to design engineers.  

  • Analysis
    • Includes SIwave-DC to analyze voltage drop and power losses
    • Includes SIwave-PI to analyze AC SYZ for PI and SI
    • Includes time-domain circuit simulation
      • Power-aware IBIS
      • IBIS-AMI
      • Transient circuit analysis
      • Proprietary SerDes analysis that enables rapid prototyping of equalizer schemes in time and statistical domains, via QuickEye and VerifEye
  • 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 to predict temperature rise, thermal-induced stress and structural integrity
  • Synopsys HSPICE integration
  • Signal net analyzer: display quantities such as characteristic impedance (Z0) for both single-ended and differential nets; provides net length, propagation delay and reference layer for selected nets
  • PDN channel builder extracts a PDN model, allowing IC designers to optimize IC power networks within ANSYS RedHawk and ANSYS Totem

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

Near-field radiation from signal net due to cavity resonance caused by power and ground planes

 

EDA Design Flow Integration EDA Design Flow Integration

ANSYS SIwave with ANSYS ALinks for EDA seamlessly integrates into existing EDA design flows by importing design geometry directly from layout tools. The resulting SYZ networks or full-wave SPICE models generated by SIwave-PI can be used in circuit simulation tools, such as ANSYS Simplorer, Synopsys HSPICE or other SPICE-compatible tools.

Cadence  
Allegro 16.0, 16.1, 16.2, 16.3, 16.5, 16.6
APD 16.0, 16.1, 16.2, 16.3, 16.5, 16.6
SiP Digital/RF 16.0, 16.1, 16.2, 16.3, 16.5, 16.6
Virtuoso 5.10, 6.14 & 6.15, 16.6 (Linux only)
   
Mentor Graphics  
Expedition v2005, v2007.1 through EE7.9
Boardstation 8.x (uses HKP design flow)
Boardstation XE v2007, v2007.1, v2007.2, v2007.3 and v2007.7 (uses HKP design flow)
PADS PowerPCB v5.2a, v2005 and v2007
   
Zuken  
CR5000 10 & higher (Zuken translator for .anf & .cmp)
CR8000 2013 and higher (Zuken translator for .anf &.cmp)
   
ODB++  
Altium Designer R10, AD13 & AD14
Mentor Expedition EE7.9.2 & greater
Mentor PADS 9.4 & greater
Zuken Cadstar 12.1 & greater
Cadence OrCAD 16.3 & greater


 

Geometry from popular layout tools can be imported directly to ANSYS SIwave.

High-Performance Computing High-Performance Computing

ANSYS SIwave-DC, SIwave-PI and SIwave include high-performance computing (HPC) options that allow the solver to use multiple threads, cores and processors to solve large simulations. This parallelization helps to enable full-packages-merged-to-board solutions for signal integrity, power integrity and electromagnetic interference.

HPC options include a unique feature called the 3-D domain decomposition method (DDM). When invoked, SIwave with 3-D DDM solves 3-D discontinuities with a rigorous 3-D field solver and then combines all domains back together for the full solution. This method retains much of the traditional hybrid method’s speed while providing full accuracy for regions in the model with complex 3-D discontinuities.

In addition, HPC invokes the spectral decomposition method (SDM) for SIwave-PI, SIwave and the SIwave Sentinel-PSI SYZ solver option. This capability significantly speeds up AC SYZ sweeps (up to 60 times during testing) by distributing frequency points over compute cores, whether they exist in an IT-managed cluster or single computer.

PCB Reference Planes for DDR3 Bus at CPUPCB reference planes for DDR3 bus at CPU

 

Multiphysics Multiphysics

ANSYS SIwave links to the greater ANSYS software portfolio for multiphysics simulation of electronic components. One option is the ability to export a power distribution map from the SIwave packages into ANSYS Icepak. This multiphysics solution enables accurate thermal modeling of IC packages and PCBs using DC power loss from SIwave as a heat source. Icepak solves the challenges associated with the dissipation of thermal energy from electronic components that may cause premature component failure due to overheating. Thermal stress can then be evaluated with ANSYS Mechanical. This multiphysics approach allows engineers or groups of engineers to perform coupled EM-thermal-stress analysis for a complete understanding of the design.

ANSYS SIwave integrates with ANSYS Icepak to evaluate thermal performance of electronic components and PCB.