New Altium Designer users may not fully understand the benefits of organizing schematic sheets into a hierarchical top-down or bottom-up perspective. As a result, users often proceed with simple (flat) schematic designs without giving a second thought to project organization. This approach can often lead to a disconnected schematic design process, especially in multi-sheet designs where net connectivity has to be maintained across multiple schematics.
What is Hierarchical Design?
A hierarchical design within Altium Designer can be defined as a design where the sheet-to-sheet relationships (the structure) in the design is represented, with sheet symbols representing the lower sheets in the design hierarchy. The symbol represents the sheet below, and the sheet entries in it represent/connect to the ports on the sheet.
In Altium Designer, starting a hierarchical design requires the creation of sheet symbols. A sheet symbol is an electrical primitive, used to represent a sub or child sheet in a hierarchical schematic. Sheet symbols also include sheet entries, which provide a net connection between parent and child schematic sheets, similar to the way that ports provide connections between schematics in a flat-sheet design. The sheet symbols can be used to organize multiple schematics on a large design and provides users with the overall flexibility to view net connections across their entire project.
In the image below, the sheet symbol is defined by a designator. This can be used to set the category of the design, with its respective file name linked to a particular schematic sheet. When defining the entries in the sheet symbol, the sheet entry names are then linked to the same name in their sub sheets.
Easy Design Navigation
In a hierarchical design composed of multiple sheet symbols, each with its own respective entry, it’s very easy to navigate to a particular sheet of the project by using Ctrl + double clicking on a sheet entry. This will focus on a particular net-named port on its respective sheet, and allows users to view its connection.
Create Your Own Hierarchical Design
In a multi-sheet design, it may be difficult to view connectivity and show the project viewer the overall design structure. That’s why it’s extremely beneficial to use sheet entries to define a hierarchical structure. This will allow project users to save time eliminate the headaches associated with multi-sheet design, as they proceed to design review for production.
Learn how to create your own hierarchical schematic design structure in Altium Designer by downloading a free white paper.