1. Ansoft Corporation Four Station Square, Suite 200 Pittsburgh, PA 15219-1119 USA (412) 261-3200 Full-Wave SPICE TM -- Technology That Bridges the Gap Between Time and Frequency Domain

2. What Is the Design Challenge? Complex structures at the board, package and chip level continue to decrease in size while being expected to perform at higher speeds. As conduction paths become electrically long and approach or exceed the physical wavelength of the signal, traditional static parasitic extraction and SPICE modeling become inadequate.

3. SPICE simulations using sub-circuits extracted from 3D models with quasi-static methods are accurate given certain assumptions. Today’s fast, electrically long, highly distributed designs may violate quasi-static assumptions. What Do Traditional Techniques Miss? Neglected effects include:  Accurate representation of structure coupling  Variation in current return paths relative to excitation current paths  Resonances in the structure  Dispersion in the dielectrics  Radiated emissions

4. 3D structures can be fully characterized by doing a full wave solution of maxwell’s equations using the finite element method (FEM) in the frequency domain. What Is the Alternative? Benefits include:  Coupled Volumetric Electric and Magnetic field solution throughout the structure  Accurate characterization of effects missed by static and quasi-static analysis at higher frequencies  Visualization of fields and currents at specific frequencies to gain insight into improving performance

5. When Is an FEM Solver Appropriate?   Use a Quasi-Static Solver  When the Electrical Length requires phase consideration  /10 is a guideline; there are exceptions  When radiation from the device must be considered  When S-Parameters are the desired output  When lossy dielectric materials have significant effects  When frequency dependent behavior must be captured Use a FEM Full-Wave Solver Problem Scale Example: Finding Signal Integrity impacts of a Via in the signal path  (OVERLAP) Example: High-speed Package with lossy dielectrics and radiation considerations

6. Frequency Domain Simulation Output  S, Y and Z Parameters  Modal Characteristic Impedance  Complex Propagation Constants  E and H Fields in Problem Volume  Near and Far Field Radiation Where’s the SPICE sub-circuit for time domain simulation?

7. How Do I Bridge the Gap Between the Time and Frequency Domain?… …Use Ansoft HFSS Version 8 with Full-Wave SPICE TM !

8. Presentation Topics  Core Technologies  Tangential Vector Finite Elements  Automatic/Adaptive Meshing  Broadband Frequency Sweeps  ALPS (Adaptive Lanczos-Padé Sweep)  Interpolating Sweep  Modes-to-Nodes Transformation  Full-Wave SPICE TM  Application Examples  Multi-Layer Board  Quad Flat Pack (QFP) with Ground  Coupled Lines with Transitions

9. Tangential Vector Finite Elements Core Technologies  Ensure Correct Electromagnetic Solution  Guarantee Suppression of Spurious Modes  Pioneered by Ansoft in 1989 for Full Wave Analysis using Maxwell’s Equations tetrahedron

10.  Automatically generate mesh based on wavelength  “Lambda refinement” results in tetrahedra of about /4 in free space  Adaptively refine the mesh to optimize tetrahedron size/ distribution to the field behavior  Solve Maxwell’s equations to obtain field solution  Refine mesh based on error analysis of each tetrahedron’s fields  Solve for fields and compare with prior solution.  Iterate until stopping criteria is met Automatic/Adaptive Meshing Core Technologies

11.  Over 10 years invested in high quality algorithms  Surface triangulation guarantees precise structure representation  Meshing algorithms tuned for robust solutions  Surface Recovery  Element Face Swapping  Element Placement  Element Aspect Ratio  Mesh Growth Rate  Manual control of the Automatic/Adaptive Meshing--Engine Core Technologies mesh is allowed if needed

12.  ALPS Fast Sweep  Compute frequency behavior using Lanczos method  Calculate requested number of frequency points using a Padé approximation  Field data across the entire bandwidth is preserved for post- processing Broadband Frequency Sweeps--Types Core Technologies HFSS V8 provides 2 methods to fully characterize a structure across a wide frequency band  Interpolating Sweep  Computes several points across the band and fits to a polynomial  Allows control of error tolerance and number of iterations  Complementary to ALPS  Provides field data at last solved frequency

13.  ALPS Fast Sweep  Wide Frequency Band  General Applications  High-Q Devices  Field Post-Processing at Arbitrary Frequency Broadband Sweeps--Comparison Core Technologies  Interpolating Sweep  Very Wide Frequency Band  Works Across Cut-Off  Less Memory  Efficient Emissions Test  Extended Applications  Anisotropic Materials  Ferrites  Periodic Boundaries

14.  HFSS traditionally works with modal field distributions at the ports. This representation does not lend itself to exciting individual lines with signals.  Modes-to-Nodes in V8 Allows  Direct control of port “voltages” instead of modal power  terminal-based S matrix  terminal-based field plots  Differential Pair Feature Modes-to-Nodes Transformation Core Technologies

15.  Circuit Simulation  Terminal Voltages  Full-Wave Solvers  Modal Concept

16. Our Commitment: Not Just Circuit Data Export. Full Nodal Support at All Stages of HFSS Simulation. Modes-to-Nodes Transformation Core Technologies

17. Boundary Manager  Separate Views for Modal and Nodal Setup Benefits  Independent Nodal Voltage Lines  Unrelated to Modal Impedance / Calibration Lines  Visualization of Mode- and Node-Based Port Fields Full Nodal Support at All Stages Core Technologies

18. HFSS->Setup Executive Parameters  Differential Pairs Benefits Common / Differential Mode Functionality  Full Circuit Parameter Support  Mixed Models  Single-Ended Lines and Differential Pairs on Same Port. = VCVC VCVC One Pair Supporting Common & Differential Modes + V D -V D Two Separate, Single-Ended Transmission Lines V1V1 V2V2 Full Nodal Support at All Stages Core Technologies

19. Matrix Data  Separate Solutions for Nodal Data Benefits  User-Defined Complex Reference Impedances  S, Y, and Z Matrices  Familiar Look and Feel Full Nodal Support at All Stages Core Technologies

20. Mode Amplitudes Node Voltages Fields Post-Processor  Node-Based Excitations Benefits  Full Near Field and Far Field Support  Multiple Excitations at One Time  Bidirectional Conversion between Nodal and Modal Excitations Full Nodal Support at All Stages Core Technologies

21. Coupled Transmission Lines Full Nodal Support at All Stages Core Technologies

22. Crosstalk Animation Full Nodal Support at All Stages Core Technologies

23. Full-Wave SPICE TM Core Technologies The core technology blocks are all in place... Broadband Frequency Sweeps Tangential Vector Finite Elements Robust Automatic/ Adaptive Meshing Modes-to-Nodes Transformation Full-Wave SPICE TM …Let’s Bridge the Gap Between Time and Frequency

24. Full-Wave SPICE TM --Defined Core Technologies  SPICE model output from Ansoft HFSS V8 full-wave solver to facilitate time-domain simulation  All resonance’s and harmonics included so that time-domain simulation is valid for the entire frequency band  Works with industry standard HSPICE, Pspice, as well as Maxwell SPICE

25. Full-Wave SPICE TM --Model Features Core Technologies  One button click to output complete time domain model  No hand generation of circuit topology  Very compact SPICE models  Very fast time domain results  Valid at all points in the specified frequency band  Full-Wave model DOES NOT add instability to complex digital or mixed signal circuits

26. Full-Wave SPICE TM --Circuit Export Core Technologies HFSS Frequency and Time Domain Circuit Simulators Star-Hspice PSpice Maxwell Spice SPICE

27. Full-Wave SPICE TM --Procedure Core Technologies  Input Device Geometry into HFSS V8  Assign Materials and Apply Boundaries  Define Terminals (multiple TEM modes only)  Solve and Do Frequency Sweep  ALPS or Interpolating  One Button Click to Calculate Terminal Matrices (multiple TEM modes only)  Export Full-Wave SPICE TM  H-SPICE  P-SPICE  Maxwell SPICE

28. Full-Wave SPICE TM --Calculations Core Technologies An inverse FFT is used to take the Frequency Domain Data into the Time Domain    Quick FFT Review

29. Full-Wave SPICE TM --Output Core Technologies The inverse FFT requires data  from 0 (DC) to f max  at evenly spaced frequency points  not good enough to simulate from 1 GHz to 10 GHz What does HFSS V8 do?  Does frequency sweep from f min to f max  Does frequency extrapolation to DC  Computes terminal S-parameter matrices  Creates device models for Maxwell SPICE, Hspice, PSpice

30. Application Examples

31. Multi-Layer Board Multi-Layer MCM Board with Traces and a Gridded Ground Plane “Carrier Layer” Forming Interconnect Between MCM and Board Devices Multi-Layer Circuit Board with Traces and Solid Ground Planes

32. Multi-Layer Board--Setup Details “Guard” Via Signal Via Symmetry H Boundaries Ports Ground Planes Note: Air region at top and bottom of the model not shown here

33. Multi-Layer Board--Analysis  Examine Results in the Frequency Domain  View Field Coupling Between Vias  Export Full-Wave SPICE TM Circuit for Crosstalk

34. Multi-Layer Board--Frequency Domain Reflection and Transmission of One Conductor

35. Multi-Layer Board--Frequency Domain Frequency Response of Coupled Signals horizontal vertical diagonal horizontal and vertical reverse coupling horizontal and vertical forward coupling diagonal forward and reverse coupling  White Circles are Signal Vias  Numbers are Top Ports  Black Circles are “Guard” Vias

36. Multi-Layer Board--Coupling Plots “Horizontal” Crosstalk “Vertical” Crosstalk

37. Multi-Layer Board--Transition to Time Domain  Use “Post Process/Matrix Data”  Re-normalize Ports to 50 ohms  Export Maxwell SPICE Model  Pspice and HSPICE also available  Create Schematic Capture Project  Import Maxwell SPICE sub-circuit  Add Source, Probes and Terminations  Run SPICE Note: Modes-to-Nodes Transformation not necessary since each port only has one propagating mode

38. Multi-Layer Board--Schematic Capture Crosstalk Circuit Note: All resistors 50 ohms

39. Multi-Layer Board--Partial Maxwell Full-Wave TM SPICE Sub-Circuit

40. Multi-Layer Board--Input Signal

41. Multi-Layer Board--Crosstalk

42. Multi-Layer Board--Data Comparison Crosstalk Data Comparison

43. QFP with Ground Plane Air Volume with Radiation Boundary Gap Ports Package Body Substrate Ground Plane Ground Straps

44. QFP--Bondwire Connections Gap Ports Ground Strap Ground Straps  Small 2D Objects Connect Bondwires to the Chip Ground  Two 2D Objects Defined as Gap Ports  Other 2D Objects Defined as Perfect Conductors

45. QFP--Schematic Capture Crosstalk Circuit Note: All resistors 50 ohms

46. QFP--Input Signal

47. QFP--Transient Response

48. QFP--Crosstalk

49. Coupled Lines with Transitions Flipped Over 5 Mode, 5 Terminal Port Air Volume with Radiation Boundary Ground Planes Substrate Microstrip Lines Striplines

50. Coupled Lines--Simulation Procedure  Generate 3D Solid Model From Allegro Layout  Import and Edit Model in HFSS V8  Setup and Run Simulation  Generate Full-Wave TM SPICE Model  Setup and Solve Model in Schematic Capture

51. Coupled Lines--Generate Model  Generate Neutral File from Allegro  Read Neutral File into AnsoftLinks  Select Specific Nets  Draw Outline Around Desired Section of Board  Export 3D Solid Model Selected Section of Board Layout Selected Nets

52. Coupled Lines--Nodal vs Modal Fields Terminal 3 Nodal Fields First Mode Fields

53. Coupled Lines--Next Four Modes Mode 2 Mode 5 Mode 3 Mode 4

54. Coupled Lines--Schematic Capture Crosstalk Model Note: All resistors 50 ohms t1t2t3t5t4

55. Coupled Lines--Input and Output t3

56. Coupled Lines--Near-End Crosstalk t1 t2 t4 t5

57. Coupled Lines--Far-End Crosstalk t1 t2 t4 t5

58. Summary  Core Technology Important for Accurate Solutions  Full-Wave SPICE TM Bridges the Gap Between the Time and Frequency Domain