EMDS for ADS Momentum

Transcription

1 EMDS for ADS Momentum ADS User Group Meeting 2009, Böblingen, Germany Prof. Dr.-Ing. Frank Gustrau Gustrau, Dortmund User Group Meeting Univ. of Applied Sciences and Arts (FH Dortmund)

2 Presentation Overview ADS Overview Passive structures! EMDS for ADS applications 3D meshing and computational domain EMDS for ADS Examples Edge coupled line filter (Mesh convergence) Bandpass-filter (Validation) Box resonance (EM fields) EMDS for ADS Demo Edge coupled line filter LTCC RLC circuit ADS Gustrau, Dortmund User Group Meeting

3 Lecture on 3D EM Modeling Based on EMDS 2006C (real 3D FEM) Branchline coupler Coax-to-waveguide transition Quarterwave transformer UWB antenna Diplexer Horn antenna Box resonance Gustrau, Dortmund User Group Meeting

4 Project and Diploma Theses EMDS 2006C, e.g. SO14 Package Mode conversion on a star quad transmission line EMC log-per antenna Car model with antenna Gustrau, Dortmund User Group Meeting

5 ADS Overview ADS User Inferface Layout EMDS 2006C ADS Schematic ADS Momentum EMDS for ADS EMPro ADS Schematic: Circuit-theory based simulator Analytical models determine input-output behaviour of components ADS Momentum: 2.5D-Method-of-Moments (MoM) simulator Full wave solver for layered media, arbitrary planar geometry, vias EMDS for ADS: 3D-Finite Element Method (FEM) simulator Full wave solver that can handle finite substrates and include 3D models EMDS (Stand alone): 3D-Finite Element Method (FEM) simulator EMPro 3D-Finite Difference Time Domain (FDTD) simulator EMDS and EMPro have their own 3D-CAD-GUI Gustrau, Dortmund User Group Meeting

6 ADS Schematic Standard components; e.g. Microstrip filter sections Microstrip filter section (+) Fast and accurate results (+) Design Guides available (+) Real time tuning capabilities!make sure that models are within their Range of Usage! Gustrau, Dortmund User Group Meeting

7 ADS Momentum Arbitrary 2D metallic structures and vias in layered media Substrates are infinite in lateral direction! Slots in metallic sheets Multilayer designs Planar antennas Visualisation of Current density Aperture coupled microstrip transition Multilayer open loop filter Patch antenna Gustrau, Dortmund User Group Meeting

8 ADS Momentum Different edge meshes!mesh quality is crucial! (central section of edge coupled line filter) Subdivide metallic strips in basic 2D cells Cell size based on a cells/wavelength-criterion Different mesh types: Transmission line and edge mesh Trade-off: Cell size / numerical effort Momentum vs. Circuit simulator More modeling flexibility More accurate results Including radiation, coupling But: increased numerical effort compared to circuit-theory based solver limited to infinite substrates 20 cells / wavelength 40 cells / wavelength 60 cells / wavelength Gustrau, Dortmund User Group Meeting

9 EMDS for ADS Finite substrates Defined as 3D vias in dielectric layers Fringing effects Broadside radiation of planar antennas Import of 3D components from EMPro Visualisation of EM fields in the computational volume But: increased computational burden LTCC RLC Circuit Gustrau, Dortmund User Group Meeting

10 EMDS for ADS Application 1: LTCC RLC circuit Four-layer LTCC RLC circuit Layout stretched x10 3D bondwire z scale view Gustrau, Dortmund User Group Meeting

11 EMDS for ADS Application 2: Chip in package Package Silicon chip Layout Ports Gustrau, Dortmund User Group Meeting

12 EMDS for ADS Application 3: Printed Yagi-like antenna H field distribution Groundplane Finite substrate Direction of radiation Direction of radiation Gustrau, Dortmund User Group Meeting

13 EMDS for ADS Application 4: Planar inverted-f antenna with 3D feeding structure Tuning patch Top patch Finite substrate Ground return Lumped port E field on ground plane Reflection coefficient s 11 Gustrau, Dortmund User Group Meeting

14 EMDS for ADS Application 5: Coaxial quarter-wave transformer 50 Ω line 70.7 Ω line 20 GHz 100 Ω line Layout Gustrau, Dortmund User Group Meeting

15 EMDS for ADS!Mesh quality is crucial! 3D tetrahedral volume mesh (Structure and air!) Adaptive mesh refinement until convergence of s-parameters is achieved (at specified frequency) Open structure: Mesh (Tetrahedral elements) Space around the structure is required Chip in package Geometry Gustrau, Dortmund User Group Meeting

16 EMDS for ADS Additional space around the structure is required 1) For microstrip design: Rule of thumb Distance from open boundary: lateral >5 line widths vertical >5-10 substrate heights Infinite distance to wall 49 x 48,5 Characteristic Impedance Z_L / Ohm 48 47, , , ,5 vertical space=lateral space=x infinite portsize Lateral distance to wall Smaller Larger x x / mm LineCalc: 9.5 GHz, h=635 µm, eps_r=9.8; w=660 µm; x=wall1=wall2=hu=x; Gustrau, Dortmund User Group Meeting

17 EMDS for ADS Additional space around the structure is required 2) For radiation problems: Distance: at least one quarter of a wavelength In order to avoid coupling to the boundary PIFA on finite substrate λ/4 λ/4 Gustrau, Dortmund User Group Meeting

18 EMDS for ADS Comparison between Momentum and EMDS for ADS Momentum EMDS for ADS Num. Method Method of Moments Finite Element Method Computational open, layered finite volume, additional domain -> Green s function space is required for open structures (microstrip ports, radiation problems) Meshing surface (2D) mesh volume (3D) mesh; based on cells/wavelength automatic (iterative) mesh refinement Example 1+2 Visualisation Current Density Electric and Magnetic Fields Example 3 Gustrau, Dortmund User Group Meeting

19 Presentation Overview ADS Overview Passive structures! EMDS for ADS applications 3D meshing and computational domain EMDS for ADS Examples Edge coupled line filter (Mesh convergence) Bandpass-filter (Validation) Box resonance (EM fields) EMDS for ADS Demo Edge coupled line filter LTCC RLC circuit ADS Gustrau, Dortmund User Group Meeting

20 Example 1: Mesh convergence Edge coupled line filter: Model definition Layout Port 1 Input line Center line Output line Port 2 Substrate h = 635 µm ε r = 9.8 (lossless) Strip w = 660 µm Perfect Conductor s = 500 µm l1 = l3 = 8.8 mm l2 = 5.6mm Boundary extension vertical =7 mm lateral = 7 mm type = open Port size (automatic) wp =13.86 mm =21 w hp = mm =11 h Gustrau, Dortmund User Group Meeting

21 Example 1: Mesh convergence Edge coupled line filter: Adaptive Mesh Refinement Mesh refinement frequency: 9.5 GHz 3 Iterations 6 Iterations 9 Iterations 18 Iterations Gustrau, Dortmund User Group Meeting

22 Example 1: Mesh convergence Edge coupled line filter: Adaptive Mesh Refinement 1200 Simulation Time / s Simulation Time / s Memory / MB Centrino 2 Duo T GHz Memory / MB 0 Iterations Iterationen Start mesh around center strip mesh after 20 iterations Gustrau, Dortmund User Group Meeting

23 Example 1: Mesh convergence Edge coupled line filter: Virtual dummy air box Idea: start with a finer mesh at the critical location Better Convergence! Air box above resonant element (Extension: ±x, ±y, +z: 1 mm) Iterations Dummy air object produces finer start mesh around center strip Gustrau, Dortmund User Group Meeting

24 Example 1: Mesh convergence Edge coupled line filter: Faster convergence Iterations (original adaptive mesh refinement) 9, GHz GHz Iterations (virtual dummy air box) 9,4 9,3 Frequency of minimum reflection over simulation time f_0 / GHz 9,2 9,1 9 8,9 8,8 Automatic mesh refinement Virtual air box Better Convergence with dummy air object! Simulation time / s Gustrau, Dortmund User Group Meeting

25 Example 1: Mesh convergence Edge coupled line filter: Momentum 20 cells / wavelength 40 cells / wavelength 60 cells / wavelength In this example 20 cells / wavelength are sufficient Gustrau, Dortmund User Group Meeting

26 Example 1: Mesh convergence Comparison and modeling differences ADS Schematic Momentum EMDS for ADS (analytical models) (Method of Moments) (Finite Element Method) Lateral Extension infinite infinite finite Radiation no yes yes Frequency GHz GHz GHz (dummy air object) GHz (without air object; converges to a slightly lower frequency) EMDS G2 ADS Schematic Momentum Conclusion: - Good agreement -In this example: Better convergence with dummy air object! Gustrau, Dortmund User Group Meeting

27 Example 2: Validation Bandpass-Filter: with and without dummy objects without dummy air objects Agilent N5230A With dummy air objects in critical regions Gustrau, Dortmund User Group Meeting

28 Example 2: Validation Bandpass-Filter: Comparison Measurement Agilent N5230A Momentum (20/40 cells/wavelength) EMDS for ADS (8:14 min) (with dummy objects) EMDS for ADS (14:16 min) (without dummy object) Final mesh Gustrau, Dortmund Take home message : Dummy objects can help the FEM simulator to set up better meshes and might be an option when considering mesh convergence User Group Meeting

29 Example 3: EM Field Distribution Box Resonance: Model definition Microstrip lines gap Substrate Case 1: Open boundary Case 2: Closed metallic enclosure Strip conductor w=1.2 mm L=7mm Distance between strip and wall s=0.5mm Airbox L=30 mm B=48 mm H=8.73 mm Substrate h=1.27 mm ε r =10.5 L=30 mm B=48 mm Gustrau, Dortmund User Group Meeting

30 Example 3: EM Field Distribution Box Resonance: Transmission coefficient What does it mean?- Why is it so? Case 1: Open boundary Case 2: Closed metallic enclosure Sidenote: In this example: Very fast convergence without dummy air objects! (Curves for 5 and 10 iterations nearly indentical.) Gustrau, Dortmund User Group Meeting

31 Example 3: EM Field Distribution Box Resonance: Modes 5.5 GHz TE 110 Box mode E field H field 7.45 GHz TE 120 Box mode E field Gustrau, Dortmund H field User Group Meeting

32 Example 3: EM Field Distribution Box Resonance: Question: What will happen if we put a lossy block at the center of the box? Lossy dielectric block 5.5 GHz TE 110 Box mode 7.45 GHz TE 120 Box mode E field Gustrau, Dortmund User Group Meeting

33 Example 3: EM Field Distribution Example 3: Box Resonance TE 110 mode attenuated TE 120 mode not influenced 5.5 GHz TE 110 Box mode Without lossy block With lossy dielectric block 7.45 GHz TE 120 Box mode Take home message : Field plots can improve the understanding of how the structure actually works E field Gustrau, Dortmund User Group Meeting

34 Presentation Overview ADS Overview Passive structures! EMDS for ADS Applications 3D meshing and computational domain EMDS for ADS Examples Edge coupled line filter (Mesh convergence) Bandpass-Filter (Validation) Box resonance (EM fields) ADS EMDS for ADS Demo Edge coupled line filter LTCC RLC circuit Gustrau, Dortmund User Group Meeting

35 Thank you for your attention! References Frank Gustrau, Dirk Manteuffel, EM Modeling of Antennas and RF Components for Wireless Communication Systems, Springer, 2006 Daniel G. Swanson Jr., Wolfgang J. R. Hoefer, Microwave Circuit Modeling Using Electromagnetic Field Simulation, Artech House, 2003 Empire XCcel, IMST, Kamp-Lintfort, 2009, Gustrau, Dortmund User Group Meeting