NI Multisim Schematic Capture and Circuit Design: Glossary

The NI Multisim environment makes schematic capture easy with several intuitive features.

This article introduce a variety of elements in the Multisim design interface and provides additional information on how these features can enhance your circuit development.

Use this glossary to understand more about Multisim features.

What You See Is What You Get (WYSIWYG) Net System 

The WYSIWYG net system is brand new to NI Multisim 11.0. This net system unifies the net names within both Multisim and NI Ultiboard. Regardless of the stages in the design flow you are working on, the net name will be consistent (whether in capture, simulation or layout). This reduces errors by avoiding naming conflicts.

The WYSIWYG net system also ensures that every net within Multisim is uniquely named. In the past there could be multiple nets named “1”, depending on which sheet of the design they are on, or whether they exist in a hierarchy (hierarchical block or sub-circuit). This is no longer permitted in Multisim 11.0.

 

 

Multisim Component Database

The Multisim component database contains the nearly 17,500 symbols used for schematic capture. To access the database you use the "Select a Component" interface (Place»Component).

The "Select a Component" database (seen in Figure 1) includes a number of specific features to note.

First you can access up to three different databases based upon the components you wish to place on your design (Figure 1 - circled in red). The database descriptions are below:

1. The Master Database contains all shipping components and is read only in order to protect models and components.
2. The Corporate Database allows you to create custom components in Multisim and save them to a database that can be shared on a network drive.
3. The User Database allows you to create custom components that can only be used by you.

Figure 1. Select a Component Dialog Box

In Figure 1 (circled in blue), you can see the logical organization of the component selection interface. Components are divided into logical groups to make searching easier. This includes a group for "sources," "basics," "transistors," "power" and "RF."

The component selection dialog also includes the component Family (Figure 2 - circled in red) in order to help further organize a group. You can then select the component from the search/browse fields (Figure 2 - circled in blue). View the selected component symbol (Figure 2 - circled in green), learn about its function (Figure 2 - circled in brown) and finally select either the SPICE model or device Footprint (Figure 2 - circled in black).

 

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Figure 2. Select a Component Dialog Box

 

 

Modeless Wiring Environment 

Multisim is made easy through a modeless wiring environment. This means that you do not need to switch between “part-placement” mode and “wiring” mode during design.

At anytime during the design process if you need to begin wiring, Multisim will automatically begin routing a net connection as it comes into proximity of a pin on a symbol. This helps to save time, and avoid repetitious tasks.

Figure 3a. The Cursor Near a Symbol Pin

 

Figure 3b. Cursor Automatically Converted to Crosshair

 

Figure 3c. Wire Routed

 

 

Database Manager

With the Database Manager, you can make edits in your database including adding user fields for important information such as vendor, status, price, availability, preferred use, and so on.

To access the Database Manager, select Tools»Database»Database Manager.

Figure 4. Database Manager

 

 

Autoconnect Passives

When placing components such as passives (resistors, inductors, and capacitors), you can place them on top of an existing wire. The component automatically wires itself into the wire without shorting it. This is called an autoconnect passive.

 

Figure 5a. Moving a Component Toward Wire

 

 

Figure 5b. Placing the Passive on Top of the Wire

 

Figure 5c. Autoconnection of Passives

 

 

On-Page and Global Connectors

With connectors, you can make virtual connections between various points in a design without having to visually connect them together. This can help improve the readability of a schematic instead of creating a "spaghetti" mess of wires on a design.

Find the new Multisim connectors by navigating to Place»Connectors»On-Page Connectors or Place»Connectors»Global Connectors.

On-page connectors are used to make virtual connections on just a single page of a design. An on-page connector is therefore local to a sheet or page of a design.

 

Figure 6. On-Page Connector

Using global connectors, you can create a virtual connection through multiple pages as well as design the hierarchy (hierarchical blocks, subcircuits, and so on). This global connector makes the voltage and currents at a particular net global to the various elements of a design.

Figure 7. Global Connector

 

 

Multisection Components

The symbol of a component (for example of an op-amp) is an industry standard description of a device. This symbol however maps to an actual integrated circuit (IC), which can sometimes contain multiple gates within a single package. These components are described as multi-section components and every gate contained in an IC package can be placed onto a schematic. This ensures that when developing a PCB layout, you can optimize your design to use the various gates of an IC.

Note the multisection component in the "Select a Component" dialog box with the tabs below the symbol (Figure 8).

Figure 8. Multisection Component in Database

When placing a multisection component, refer to the following tool-tip dialog (Figure 9a) before and after placing the individual section of the IC.

Figure 9a. Multisection Dialog

 

Figure 9b. Placed Multisection Component

 

Design Hierarchy

You can modularize your design by using subcircuits and hierarchical blocks. With these design aids, you can replace circuitry with blocks that contain your design topology. By doing this, you can clean up a design and represent it logically in a block diagram format.

 

 

Subcircuit

A subcircuit is a hierarchical design element that represents circuitry in a block to help clean up a circuit diagram. A subcircuit exists only as part of the design on which you place it. You cannot reuse it anywhere outside that specific design.

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Figure 10. Subcircuit

 

 

Hierarchical Block

A hierarchical block is a hierarchical design element that represents circuitry in a block to help clean up a circuit diagram. However, you can save a hierarchical block as a separate file that you can then reuse in other design topologies. This allows for modular reuse (capabilities not available in a subcircuit).

You can create libraries of hierarchical blocks that you can easily reuse for a variety of designs once you have created and validated them.

Figure 11. Hierarchical Block

 

 

Learn How to Design with Multisim

You have now learned about some of the features of the Multisim schematic capture environment and are ready to put them to use. View the Introduction to Multisim: Learn how to Capture and Simulate in Less than 30 Minutes article to get started using features such as:

1. The WYSIWYG Net System
2. Component Database
3. Modeless Wiring 

 

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