Transistor Folding

Transistor folding lets you interactively divide the following into two or more layout instances with terminals all connected in parallel to the same nets:

• an individual transistor or a chain of transistors
• an already folded transistor or a chain of folded transistors
• an individual FinFET device or a chain of FinFET devices
• a multi-fingered device or transistor.

Folding lets you change the aspect ratio of the devices in your design while retaining the original location and orientation of the device that was folded. The net on the left of the device (or on the bottom for vertically-oriented devices) is the same before and after folding.

The transistors to be folded need not be bound to a schematic instance but they must be assigned to a component type, which stores the width attributes set on the cell.

If the devices to be folded are FinFETs, the devices must have their Number of fins parameter or the Width parameter set to enable folding.

You set this information using the Edit Component Types command. For more information, see Component Types Mode.

The individual device folds are named instName.integer in the layout. For example, if you have an instance named I0 and you divide it into three folds, the folds are named as follows.

Instance Name	Folded Instance Names
I0	|I0.1 |I0.2 |I0.3

You must also have the mfactorSplit environment variable set to t in a setup file for the design, otherwise, the Generate Folded Devices command does not work.

Related Topics

Unit Identifiers in Layout XL

Folding a Multi-fingered Device to Create Split Fingers

Rounding Parameter Values

Generate Folded Devices Form

retainSelectionSet

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