Altium Designer Documentation

NFS_21_0New PCB Length Tuning Patterns_AD

Created: August 10, 2020 | Updated: December 1, 2020
All Contents

Length matching is a critical element of high-speed design, usually solved by carefully tuning the lengths of critical routes. This release sees the introduction of new Trombone and Sawtooth tuning patterns, and improvements to the Accordion pattern.

New and Improved Tuning Patterns

This release sees extensive improvements to both single-sided and differential pair length tuning capabilities. New Trombone and Sawtooth tuning patterns have been added, which introduce the concept of a tuning sleeve. The sleeve concept simplifies moving and reshaping the tuning pattern, allowing you to slide the tuning pattern along the original route path and around bends.

New Tuning Patterns

Length tuning now supports all three popular tuning patterns: Trombone, Sawtooth, and Accordion.

Press Tab after launching the Length Tuning command to choose the pattern.Press Tab after launching the Length Tuning command to choose the pattern.

  • Press Tab after launching the Length Tuning command  and choose the required Pattern in the Interactive Length Tuning mode of the Properties panel, before you start length tuning a net.

Working with the New Tuning Patterns

For the Trombone and Sawtooth patterns, the polygonal area that the pattern is constructed within an envelope that can be thought of as a sleeve. Click to select a placed pattern and display the sleeve.

The trombone and sawtooth patterns are built within a sleeve shape, which supports a variety of shape-change behaviors.The trombone and sawtooth patterns are built within a sleeve shape, which supports a variety of shape-change behaviors.

There a number of different movement and size-change behaviors available, depending on where you click and hold on the sleeve. There are three zones where you can click and drag, these are shown in the image above.

  • Click and Drag on Zone 1 or 2 to lengthen or widen the pattern. Note that it is not necessary to click on a handle to resize the pattern, use anywhere along the sleeve edge.
  • Click and Drag on Zone 3 to freely move the pattern along or perpendicular to the original route path.
  • Edit the properties of the selected pattern(s) in the Properties panel.

The Shift and Ctrl shortcuts can be included during a click and drag action, modifying the behavior in the following ways:

  • Shift + Click and Drag on Zone 1 or 3 to slide the pattern along the original route path, maintaining the pattern's lateral distribution across the route path.
  • Ctrl + Click and Drag on Zone 2 or 3 to move the pattern perpendicular to the original route path.

Note that the Shift and Ctrl shortcuts are modifiers, they can be applied/released during a Click and Drag action. For example, press Shift while lengthening a pattern to switch to sliding mode, then release to resume lengthening. 

To re-center a selected pattern, enable and then disable the Single Side option, the pattern will default to a centered location.

Sawtooth Pattern Properties

  • Angle - slope of the leading and trailing tooth edges, relative to the original route path of the net being tuned.
  • Tooth Width - width of the top of the tooth.
  • Actual Height - current tooth height, measured from the centerline of the original route path being tuned, to the centerline of the tooth's top track segment. Press Tab during placement to edit the Actual Height value.
  • Min Height - minimum allowable tooth height.
  • Min Joint - minimum length of the first colinear track segment placed before the first tooth is created.
  • Single Side - create the tuning pattern so that it only projects in one direction from the original route path. Press the S shortcut during placement or interactive editing to toggle the option on or off.
  • Fixed Size - fixes the Sawtooth Height to the current height, and removes any teeth that are not at that fixed size.

Trombone Pattern Properties

  • Space - the distance between the centerlines of adjacent trombone switchback paths. Press the 3 or 4 shortcut keys to interactively decrease or increase the Space, in increments of Space Step.
  • (Space) Step - this is the amount the Space value is changed when the 3 or the 4 shortcut key is pressed during trombone placement or interactive editing.
  • Miter - percentage that the corners of the tuning pattern are mitered when the Style is Mitered Lines or Mitered Arcs. Press the 1 or 2 shortcut keys to interactively decrease or increase the Miter, in increments of Miter Step.
  • (Miter) Step - this is the amount the Miter value is changed when the 1 or 2 shortcut keys are pressed during trombone placement or interactive editing.
  • Style - style of the trombone corners, choose between Mitered Lines, Mitered Arcs or Rounded. The Style is changed by pressing the Spacebar shortcut key during trombone placement or interactive editing.
  • Single Side - create the tuning pattern so that it only projects in one direction from the original route path. Press the S shortcut during placement or interactive editing to toggle the option on or off.

Rotate an Accordion Pattern

The PCB editor's accordion pattern has been updated to support the rotation of a placed accordion pattern.

To rotate a selected accordion, hold Ctrl then:

  • Click and drag on either end of the accordion selection box to pivot around the opposite end of the accordion.
  • Click and drag on either side of the accordion selection box to pivot around the center of the accordion.
  • Press the R key during rotation to toggle (on/off) the rotation to snap in 45-degree increments.

The accordion pattern does not support the sleeve concept, so does not support placing or sliding around a corner.

 

 

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