Accelerate RF, Microwave Design (5/5)

Bulk installation of RF shielding vias can be time consuming. With PADS Professional, you can do this in a matter of seconds. All holes are grouped so that they can be moved or deleted together. Transitions can be set based on custom rules.

Lesson 5 – Flashing software along the track and stitching polygons

  1. Double click the PADS Pro Designer VX.2.x icon on the desktop or select
    START Menu> PADS Pro Tools VX.2.x> PADS Pro Designer VX.2.x.
  2. From the PADS Professional Designer start page, click Open and open
    C: RF Design Lesson5 PCB Lesson5.pcb.
    • If a licensing dialog box appears, make sure the option PADS Professional RF Design installed and click OK
  3. Zoom in on the area with the track TX… Let’s start by adding stapling holes along the wire, from the amplifier (BGA) to the antenna input port.
    • Choose a tool Add Via on the panel RF
    • Select a chain TX2
    • In the section Placement Control> Algorithm choose Interactive Start / End
    • Adjust the rest of the parameters in the dialog box according to the picture:
    • Click on Apply
    • An outline appears around the wire. Now you can select the starting and ending points of the stitching contour. Set the starting point near the amplifier pin and the ending point at the antenna input
    • Repeat for the procedure for TX1
  4. Turn off the display of the top layer of the board and turn on the display of the bottom layer to see why some software did not install. You have the opportunity to host software without DRC, if necessary
  5. Repeat this process for chains RX1-4
  6. In order for our antennas to function properly, we need to get rid of coplanarity with the ground polygon. To do this, we can define exclusion zones for the polygon.
    • Go to the menu Planes> Plane obstruct
    • Open the Draw toolbar. (Right-click on the main toolbar and select Draw)
    • Draw a polygon as shown in the picture:
    • In the window Properties install Layers into position ALL
  7. In most designs that use RF paths, to reduce circulating currents, among other things, cross-linking of ground polygons is required to reduce the circulating currents.
    holes. This can be a very time consuming task if done manually. In our project, we need to do this around the wires TX1-2 and RX1-4.

    • PADS Professional allows you to stitch polygons and Conductive Shapes. For this we need to create an earthen polygon on the top layer on top of the existing one. This will not create problems with polygon pouring or for production.
    • Go to the menu Planes> Plane Shape
    • Choose a tool Polygon on the panel Draw
    • Create a polygon as shown in the picture:
  8. Now we can fill this polygon with vias.
    • Choose a tool Add Via on the panel RF
    • Go to the tab Stitch shape
    • Fill in the settings in the Add Via dialog box as shown in the figure:
  9. Before piercing polygons with vias, you can save these settings for later use and assign them to other polygons in the project.
    • To save the settings, click on the icon Save in the Add Via dialog
    • Give a name for this configuration – Lesson5
  10. Now we will assign these rules for the polygon that needs to be stitched.
    • If not already selected, select the polygon that was just created
    • Double click on it to bring up the window Properties or click on the polygon PKM and select Properties
    • Select from the dropdown Stitchvia Scheme configuration Lesson5
    • Click PKM by polygon and select Generate Stitchvias
    • If you turn off the display of polygons, then you should see the following picture:
  11. This concludes Lesson 5

Test 30-day licenses can be requested HERE

Materials for this and previous lessons can be downloaded HERE

You can also watch a video version of this tutorial:

Previous lessons:
Lesson 4 – Advanced RF Trace Capabilities
Lesson 3 – Setting Up Design Rules for RF Objects
Lesson 2 – Updating the Schematic and Placing RF Objects on the Board
Lesson 1 – Creating RF Objects in Topology and Schematic

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Filipov Bogdan pbo, Product Manager for PADS solutions at Nanosoft.

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