next up previous contents index
Next: The Delete Button: Delete Up: The Properties Button: Property Previous: The Edit Button: Edit   Contents   Index

The Add Button: Add New property

In physical mode, the Add button will produce a drop-down menu containing the following items.

The nomerge choice will add a nomerge property (a property used by the extraction system) to the selected object or objects.

The flatten property applies to electrical and physical cells and instances. It is used during association and LVS to determine if the contents of the instance master should be logically promoted into the containing cell (see 16.4). Although Xic can handle most hierarchy differences automatically and transparently, this property may be used when needed to force proper behavior.

If a flatten property has been applied to the master cell, then instances of the cell will be flattened, unless the instance also has the flatten property applied, in which case the instance will not be flattened. If the master does not contain a flatten property, then and instance will be flattened only if the instance has a flatten property applied. Thus, the flatten property of an instance reverses the effect of a flatten property applied to the master.

The FlattenPrefix variable, and equivalently the Cell flattening name keys entry area in the Net and Cell Config page of the Extraction Setup panel from the Extract Menu, provide another means of causing instances of cells to be flattened.

The any choice allows an arbitrary property to be added. This will initiate prompting for a property number and string to add.

In electrical mode, the Add button brings up a menu of property types that can be added. Selecting an entry will initiate prompting for the associated string. Any selection in the listing will be ignored. Unlike the case of the Edit button, the arrow keys and subsequent selection in the listing will not affect the prompt line.

With the Global button off, completion of editing by pressing Enter will ``add'' the new property to the current object. In electrical mode, properties other than the other property will be replaced if they exist, since there can be at most one such property. There can be arbitrarily many other properties, or properties of any number in physical mode. Such properties are always added and not replaced.

If the Global button is active, an identical copy of the property will be added to each of the devices in the internal list. This will be a replacement for electrical properties other than other, and an addition otherwise. Unlike the Edit button case, there is no individual prompting for a string for each device. The initial string (and number, in the case of physical mode) is added to each object.

In electrical mode, the Add menu contains buttons for the modifiable device and subcircuit instance properties listed below. Unless stated otherwise, there can be at most one each of the properties described below. This is enforced by Xic, i.e., attempts to add a second property of a given type will cause replacement, not addition.

The name button allows the modification of a name property. The name property specifies the device or subcircuit instance name to SPICE. Unlike the other user-settable properties, the name property always exists. If not explicitly set by the user, the device name will be generated internally. However, if a correspondence to an existing SPICE file is necessary, the name must be specified. Xic allows any name, however for the device to be recognized by SPICE, the name must start with the device's key letter as expected by SPICE. Deleting the name property simply reverts back to the internally generated name.

If an assigned name property conflicts with an internally generated name, the internally generated name will be updated so as to not conflict by appending ``_N'', where N is some integer.


The model and value buttons allow addition of a model or value property, respectively. Only one of the model or value properties should be used per device, as this really represents two different names for the same text field in SPICE output. One has the choice a supplying a device model or component value to the device, but not both. These properties generally apply to devices only, not subcircuits.

The param property is a catch-all for additional parameters found in the device and subcircuit instance lines in SPICE, such as initial conditions or device geometrical factors. The string will generally contain a list of name=value terms, each separated by white space. Only one param property is allowed.

The devref property provides the name of the controlling device to current-controlled sources and the current-controlled switch. At most one devref property is allowed.

The other button allows addition of an other property. These properties have no significance to Xic and are not used in SPICE output. They can be used to store alternate values for the model, value, or param properties, or to store any other information desired by the user. There can be arbitrarily many other properties per device or subcircuit instance.

The nophys button allows addition of a nophys property. This property does not affect SPICE output, but specifies that the device or subcircuit instance has no physical implementation. When Xic is associating physical and electrical objects for extraction and LVS, a physical implementation will not be sought for objects with this property.

When the property is created, the user is prompted as to whether the device terminals should be shorted together during LVS. Devices that have the nophys property applied will be rendered using a different color than ``normal'' devices. See the description of LVS in 16.16 for a more complete discussion of the use of this property.

This will add a flatten property, which applies to electrical and physical cells and instances. See the description in the listing of physical properties above.

The nosymb button is used to add a property to electrical subcircuit instances which forces them to be displayed as expanded, whether of not the master cell of the instance is symbolic. Instances with this property will behave in all respects as if the master were non-symbolic. Thus, instances of the same master can be displayed symbolically or not, in the same design. This property uses the same property number as the symbolic property applied to cells.

The range button is used to add a property to electrical device or subcell instances (other than terminal devices) that vectorizes the instance. The user is prompted for two non-negative numbers which define the subscripting range. Vectorized instances and connection rules are discussed in 4.2.9.

next up previous contents index
Next: The Delete Button: Delete Up: The Properties Button: Property Previous: The Edit Button: Edit   Contents   Index
Stephen R. Whiteley 2022-05-28