MWO – Application of EM Structure in Filter Design Soh Ping Jack Sabarina Ismail

2 DISTRIBUTED FILTER DESIGN PROCESS Filter Specification Low-pass Prototype Design Scaling & Conversion Filter Implementation Optimization & Tuning Done using MWO Board Specification Additional Step in EM Structure

3 DISTRIBUTED FILTER DESIGN PROCESS A. BOARD SPECIFICATION 1. Know the board’s parameters 2. Know how to operate in EM Structure 3. Know how to define board parameters 4. Know how to use TxLine Calculator 5. Know how to draw structures & ports 6. Know how to add results graphs 7. Optimize & tune filter to get best response To do this you have to be familiar with MWO’s EM Structure

4 DISTRIBUTED FILTER DESIGN PROCESS

5 1.0 KNOW THE BOARD PARAMETERS TODAY’S TASK To design a low pass filter on a RT/Duroid 6002 board with the following parameters: a. tanδ = b. ε r = 2.94 c. Metallization Layer Thickness (t) = 35 um d. Substrate Height (h) = 1.6 mm e. Desired Freq Range (f) = 1 GHz

6 1.0 KNOW THE BOARD PARAMETERS Photo Board Cross Section a. tanδ = b. ε r = 2.94 c. Metallization Layer Thickness (t) = 35 um d. Substrate Height (h) = 1.6 mm

7 1.0 KNOW THE BOARD PARAMETERS Photo Board Cross Section Photo Resist Layer Copper Foil Layer RT/Duroid 6002 Dielectric Layer Photo Protective Film

8 DISTRIBUTED FILTER DESIGN PROCESS

9 2.0OPERATING IN EM STRUCTURE 2.1Working in the EM Structure Environment To add a new EM Structure, right-click on “EM Structure” icon and select “New EM Structure”

10 2.0OPERATING IN EM STRUCTURE 2.1Working in the EM Structure Environment A pop-up window will appear after clicking “New EM Structure”, click on “Create” button Click on “Create”

11 2.0OPERATING IN EM STRUCTURE 2.2Setting Project Options (Freq Sweep) To edit simulation freq sweep, double-click on the “Project Options” icon

12 2.0OPERATING IN EM STRUCTURE 2.3Setting Project Options (Freq Sweep) To edit simulation freq sweep, double-click on the “Project Options” icon Define desired “Start Freq”, “Stop Freq” & “Freq Step”. It should not be too refined in an initial simulation List of the simulated freq points will be listed down when “Apply” button is clicked

13 DISTRIBUTED FILTER DESIGN PROCESS

14 3.0DEFINING BOARD PARAMETERS 3.1Defining an Enclosure To modify an enclosure’s property, double-click on the “Enclosure” box to trigger a pop-up window

15 3.0DEFINING BOARD PARAMETERS 3.2Defining an Enclosure – Enclosure Tab X and Y-dimensions & Divisions will determine Cell Size (resolution of a mesh in the structure)

16 3.0DEFINING BOARD PARAMETERS 3.3Defining an Enclosure – Dielectric Layers Define RT/Duroid 6002 properties on Layer 2 Define air properties on Layer 1 (Air thickness = 10 x substrate thickness)

17 3.0DEFINING BOARD PARAMETERS 3.4Defining an Enclosure - Boundaries Layer above Layer 1 is defined as “Approximately Open” Layer below Layer 2 is defined as “Perfect Conductor”

18 DISTRIBUTED FILTER DESIGN PROCESS

19 4.0TXLINE CALCULATOR 4.1Triggering the TXLine Calculator To open up the TXLine Calculator, go to “Tools” and click on “TXLine”

20 4.0TXLINE CALCULATOR 4.2TXLine Calculator Main Interface Enter all parameters required for impedance, freq, electrical length, & substrate information

21 4.0TXLINE CALCULATOR 4.3Using TXLine Calculator to know W & L 50 Ω 30.75Ω 50 Ω Ω Ω

22 4.0TXLINE CALCULATOR 4.4 W & L for 50 Ω Line For a 50Ω Line; 1.L = mm 2.W = mm

23 4.0TXLINE CALCULATOR 4.5Drawing W & L L = mm W = mm

24 DISTRIBUTED FILTER DESIGN PROCESS

25 5.0DRAWING STRUCTURES & PORTS 5.1Drawing Rectangular Structures To add a rectangular shaped patch, click on the “Draw Rectangular Conductor” icon at the top toolbar Drag the mouse cursor to the desired X and Y dimensions

26 5.0DRAWING STRUCTURES & PORTS 5.2Drawing Patch & Feedlines – Adding Port To add an edge port on a specific section of a line, click on the “Draw” and select “Add edge port” Important: Please ensure that the desired section of a line where the port is to be placed is clicked on first

27 5.0DRAWING STRUCTURES & PORTS 5.3Drawing Patch & Feedlines – Placing Port After selecting, place the port on the edge of the feed line. The port will be active indicating a legal/valid placement of the port on a specific edge on the feed line. Note: The edge port will be labeled “1”, “2” and so on, to indicate the port number. In this case, a filter has two ports

28 5.0DRAWING STRUCTURES & PORTS 5.4Drawing Patch & Feedlines – Extending Port After placement of the port, go to the edge of the port till a double-sided arrow is seen. Then start dragging a port extension inwards. An arrow like this should be seen Note: Port extension should be at least 3 times the height of the substrate. In this case, it is 3x1.6mm=4.8mm

29 DISTRIBUTED FILTER DESIGN PROCESS

30 6.0ADDING RESULTS GRAPHS 6.1Adding Results Graphs & Charts To add a result graph, right-click on the “Graph” icon on the left window and select “Add Graph”. A pop-up window will appear

31 6.0ADDING RESULTS GRAPHS 6.2Adding Results Graphs & Charts – Graph Types A pop-up window like this will appear, select the appropriate type of

32 6.0ADDING RESULTS GRAPHS 6.3 Adding Results Graphs & Charts – Measurements After inserting the appropriate graph type, it still does not know what type of parameters that is to be plotted on it. To define this, right click on the “Graph’s Name” and click on “Add Measurement”

33 6.0ADDING RESULTS GRAPHS 6.4 Adding Results Graphs & Charts – Parameters A pop-up window like this will appear, select the correct EM Structure’s result to be plotted by selecting the correct Data Source Name Check on the correct parameter. In this case, it is S11. Ensure that the “dB” checkbox is checked

34 6.0ADDING RESULTS GRAPHS 6.5Starting a Simulation To start simulation, click on the Analyze button on the tool bar at the top

35 6.0ADDING RESULTS GRAPHS 6.6Viewing Results Since this is an 0.5 dB equal ripple LPF; 1.Pass band starts from MIN to 1GHz 2.Stop band starts from 1GHz to MAX A good filter will have: 1.S11 response < –10dB value at pass band 2.S21 response > -3dB value at pass band 3.S21 response < -10dB value at stop band

36 7.0D.I.Y No 1 Try to finish and simulate the 0.5dB Equal Ripple, N=3, 1GHz LPF 50 Ω 30.75Ω 50 Ω Ω Ω

37 7.0D.I.Y No 1 0.5dB Equal Ripple, N=3, 1GHz LPF Sim Results

38 7.1D.I.Y No 2 Try to finish and simulate the Max Flat, N=3, 1GHz LPF 50 Ω 25Ω 50 Ω 100 Ω 25 Ω

39 7.1D.I.Y No 2 Max Flat, N=3, 1GHz LPF Sim Results

REFERENCES Pozar, D.M. (2005) Microwave Engineering 3 rd Ed. John Wiley & Sons, N.J, USA Pozar, D.M. (2001) Microwave and RF Design for Wireless Systems, John Wiley & Sons, N.J, USA

REVISION HISTORY VersionDateCommentsAuthor R Initial DraftP.J Soh