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What's Good About SigXp UI Changes? SPB16.3 Has Many New Enhancements!

Comments(1)Filed under: PCB design, Allegro, SPB 16.3, SigXP UI, layer stacks

The SPB16.3 SigXP UI has been enhanced to focus on giving users better access to information already available in SigXp, reducing the number of steps needed to accomplish simple tasks, provide functionality that enable easy data manipulation and provide better setup and default for an improved out of the box user experience.

In addition to those enhancements, a new layer stack approach has been added to SigXp, similar to PCB SI. 

Here's an overview of some of the SigXp various enhancements.


Access to Information

There is a lot of information available in SigXp, but it requires some searching and is sometimes not found. For example, what are the properties of a trace on the canvas, or which model is used for an object on the canvas.

Context sensitive right mouse menus are now available which allow you to access information when you right click on an object.

This menu has different menu options depending on where you right click (empty canvas, trace, IO buffer, etc.).

The Menu items include:

Parameters Open the Parameters tab and selects the current object for immediate browsing and change
View Trace Parameter Open the Trace Parameters form. Pre-16.3, this is only available when right clicking in the Parameters tab. This menu is only available on trace models.
{Model Name} The name of the model used by that object. Selecting it brings the View Model window as obtained from the Model Browser form. This menu is only available on trace and via models.
Change Buffer Model Open the Set Buffer Parameter form, which allows you to select a different buffer model.
Stimulus Set the stimulus on a buffer model
Rotate Right Rotate the current object 90 degrees clockwise.
Rotate Left Rotate the current object 90 degrees counter clockwise
Mirror Mirror the selected object on the X axis.
Move Move the selected object(s)
Delete Delete the selected object(s)
Copy Copy the selected object and allow user to place it on the canvas
Change Layer Available on a Trace when a cross section is defined. Allows you to select a different layer on which the trace belongs. This menu contains a submenu and with each layer defined in the cross section.

In addition to those context sensitive menus, some functions are provided when right clicking on the empty canvas.

Add Elements Open the Add Part dialog
Add Notes Open the Note editing form
Manage Layer Stacks Open the new Layer Stack Manager dialog
Preferences Open the Preferences form



The menus have been modified slightly to align some functions.

A Recent Topologies selection has been added to the File menu. This includes the recent topologies opened with the tool.


Data Manipulation

Noun-Verb Mode

The Canvas mode that exists today has been replaced by noun-verb mode similar to Allegro PCB Editor. As a default, no mode (such as Move) is selected. The selection is done first, and the action is chosen from a menu.

For example, if you want to move an object on the canvas it can be accomplished by selecting the object and, while holding down the mouse button, start dragging. Another way to move (delete, copy, rotate) is to right click on the desired object and select the action with the context sensitive menu, or use the main menu on the selected object(s). Multiple objects can be selected by drawing a box around them.

Add Element Toolbar

New Add Element toolbars have been added that allow quick access to available parts.

Add Passive Devices
Add Uncoupled Interconnect
Add Terminators
Add IO Cell
Add Coupled Interconnect
Add Vias


Drop-down lists are available when a selection can be made. For example, selecting the arrow on a coupled interconnect icon results in the following selections:


Layer Stack (Cross-section)

The simplified layer stack found in pre-SPB16.3 SigXp is adequate for some topologies and some rough design but needs more layer definitions to match the board from which the topology was extracted. An enhanced layer stack can now be defined in SigXp.

In the current layer stack implementation, a trace has two or three layers depending on the type (three for broadband and CPW and two for the others). The layers are represented by d1, d2 and d3.

SigXp has been enhanced to include the same Cross Section as Allegro.

Use of the Simplified Layer Stack

When a new design is first created, the old (current) layer stack is the default. You can continue using the tool and be ready to place parts with a simplified layer stack of two layers. Parameters can be modified the same way they are today.

This feature is useful and will remain available to users who need it.

Defining a New Layer Stack

If you need a more complex layer stack that has more than two layers or you want to define different parameters for each layer, you can access the layer stack editor that is available in Allegro PCB SI.

A Manage LayerStacks selection has been added to the Setup menu. Selecting this opens the LayerStack Manager.


This dialog can also be accessed through the Manage LayerStacks icon


Managing Layer Stacks

The layer stack manager allows you to create, delete, rename, edit and import layer stacks in the topology.

The manager is presented in the form of a list that shows available stackups and a series of buttons to perform the actions described below.

Create Used to create new layerstacks in the topology. You are prompted to provide a name for the stackup and a template from our pre-defined stackups. After creation, the stackup is added to the list.
Delete Remove the selected stackup from the topology. If any traces in the topology are using a layer from this stackup, they will revert to floating traces.
Rename Rename the selected stackup
Edit Opens the Stackup editor to edit the currently selected stackup. When you select OK, the stackup is updated in the topology and all traces using it are automatically updated.
Import Import stackup from an existing board file (.brd) or a tech file (.tcf).



When a topology is extracted from a board file, the layer stack found in that design is brought over in the topology for use by SigXp


Adding Parts

When adding a new trace to the canvas, it is not assigned to a specific layer. You can change the assigned layer by selecting a different layer from the right mouse menu or in the Trace Parameters.



Interconnect Parameters

When a Layer Stack is defined in a topology file, the simplified stackup is not available. In that case, most of the traces parameters (dielectric constants, thicknesses, etch factor, etc.) do not make sense anymore because they are available from the cross-section.

The editable parameters that are available on traces are:

  •     Length
  •     Layer (more than one for broadside models)
  •     Trace Width

Model Solving

With the simple layer stack that is available today, the model that is solved contains only those two layers (d1, d2). When a real cross section exists in the topology, that layer stack is used and therefore rendering an identical model as found in PCB SI.

Two benefits come out of this. First, the simulation result should be the same as PCB SI. Second, when extracting from a board to SigXp, the models do not need to be resolved for the simplified cross-section.

Rotate and Mirror

The Rotate and Mirror functions have been enhanced to support all objects on the canvas.


Menus have been cleaned-up. For example, the Transform > To Constraint Manager sub-menu is no longer a sub-menu with only one item.


When moving the mouse over objects on the canvas, you have datatips (also known as tooltips) that briefly describe the objects. Those datatips appear only when the mouse becomes still for a second on top of an object.

The content of the datatips is dependent on the object type.


A toolbar customization dialog has been added to the View menu to customize the toolbars available in SigXp.



In an attempt to get SigXp to more closely resemble the appearance of Allegro PCB Editor and SI, the different "tabs" at the bottom have been made into individual dockable toolbars. These can be docked on any side of the canvas (when it makes sense) and can be pinned/unpinned (foldable).

The Command and Results window can only be docked on the top or bottom.

In addition to those enhancements, the mouse wheel is now able to scroll up and down in those windows.

As always, I welcome your input as to how you're using these new features.

Jerry "GenPart" Grzenia


By Maxwell86 on January 22, 2010
Nice write-up Jerry.  Every time I show the new SigXp to a customer the reaction is the same .... "Wow, that is a nice User Interface".  I'm interested in hearing if your readers think this makes Allegro PCB SI technology more accessible to more of the "non-SI types" at their company.

Brad - PCB SI product manager

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