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Simulation - Define Logic Gate

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Use this when editing a Part to define the Part as a Logic Gate.

Use this on a Logic Gate component in a schematic design to change its propagation delay, or to replace it with a Logic Gate part using a different number of inputs, or of a different logic type.

These parts are implemented by using Functional Modelling. They have their Spice Type Built-in Function set to Gate.

Shortcuts

Default Keys: F7

Default Menu: Simulation

Command: Edit Spice Value/Model

How To Add A Logic Gate

There are various ways to add a Logic Gate to a Schematic Design:

  1. From the Parts toolbar, click on the Digital Generic pop-up to display the Digital Generic toolbar. Click on the Logic Gate button.
  2. From the Parts Browser, click on Spice Category, then on Digital and Generic to display the Digital Generic parts. Drag the Logic Gate part name into the design. Note: This method may not work if you have changed the part categories.
  3. Use Component from the Insert menu to add the Part called Logic Gate from the SPICE library.

Whichever method is used, you should be presented with the Define Logic Gate Dialog described below. This works because the part named “Logic Gate” has a blank function definition which forces the dialog to be given to get the required definition from you.

How To Define a Logic Gate

In a Schematic Design, select the Logic Gate device(s) that you wish to change. Press F7 or use the Edit Spice Value/Model option from the Simulation menu, or from the shortcut menu.

From a Parts Library edit the required Part. Press the Edit Spice button on the Details tab. Make sure the Built-in Function is set to Gate and press the Edit Definition button.

In both cases the following dialog will be displayed:

Number Of Inputs

Enter the number of inputs into the gate. Valid values are from 1 to 32.

Propagation Delay

Type in the timing value used for the rise and fall delays.

Gate Type

Choose the required gate logic type.

Changing the Symbol

If editing a Part, make sure the chosen Number Of Inputs and Gate Type match the Symbol that is used by the Part.

If editing a component in a schematic design, pressing OK with changed Number Of Inputs or Gate Type will force the component to be replaced with a Part from the Library that matches the new specification. If no suitable Part exists, an error message will be given giving details of the Part that will need to be created.

Editing Multiple Components

If any of the fields are set to then some of the components you are changing have different values for that field. Clear this field and enter the required value for all components, or leave as to tell components to keep their original values for that field.

The same applies to Radio Buttons, where no button being set indicates the components have different values for this field.

Edit Device Type | Functional Modelling

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