Accelerate RF, Microwave Design (3/5)

RF projects usually have stringent clearance requirements. With PADS Professional, you have complete control over the clearance for all RF elements. Control can be carried out not only on the layout layer, but also on adjacent layers. Also, clearance rules can be specified globally for the entire circuit or individually for each individual circuit element.

Lesson 3 – Configuring Design Rules for RF Objects

In this lesson, we’ll look at RF / Microwave-specific design rules to help you cope with complex design requirements.

  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 Lesson3 PCB Lesson3.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 two antennas TX1 and TX2that you posted in the second lesson.
  4. Go to the menu RF> Group Clearances
  5. The following dialog box will appear. In this dialog box, you can set the specific clearances for the RF groups that we have formed in the schematic.
    • Select a group P2
    • On the right side of the dialog box, change the Pad rule to 20 and click Apply… Notice how the gap around the objects in this group has changed. Return the gap to its original value. 10 and press Apply
  6. Next, we’ll look at the rules RF Entry Rules… The purpose of these rules is to control how a transmission line can enter or leave a pin of an RF object or component in a circuit.
    • Go to the menu RF> RF Entry Rules
    • Explore the options for this dialog box by clicking on the various items, but not
      applying changes. The RF objects we are working on as part of this project do not require these rules to be set.

  7. In the second lesson, we talked about the parameters of RF elements. The topology editor also has similar options for controlling these parameters.
    • Highlight one of the TX antenna segments
    • Click PKM and select RF Parameters
    • Examine the contents of this dialog, but do not save any changes
  8. Finally, it should be noted that clearance rules can be specified separately for each RF element. Earlier we set some gaps for all the elements in the group. Here we can set rules for each element of the RF circuit.
    • Highlight a segment to one of the TX antenna
    • Click PKM and select Clearance Rules
    • From the dropdown list Clearance type you can choose a specific rule: Segment to Trace, Via, Plane, pad, mask
    • To create a new rule, click on the blue icon in the section Clearance Rules
    • In the window on the right, select one of the key points
    • The field is activated Clearance Valueand you can enter the appropriate rule. You can also drag the key point to define the gap value.
    • This can be done on either side of the selected segment, allowing very detailed clearance to be achieved.
    • Exit this dialog without saving any changes
  9. This concludes Lesson 3

Test 30-day licenses can be requested HERE

Materials for this and subsequent lessons can be downloaded HERE

You can also watch a video version of this tutorial:

Previous lessons:
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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