Electric VLSI Design System User's Manual

Chapter 6: Advanced Editing

6-9: Networks
6-9-4: Power and Ground

Identification of a power network is done by finding:

a Power node from the Schematic technology;
an export in the current cell that has the "power" characteristic;
an export in the current cell that begins with the letters "vdd", "vcc", "pwr", or "power";
a port on a component in the current cell that has either of the above two properties.

Ground networks use the same rules, except that the acceptable port names begin with "vss", "gnd", or "ground".

All supply networks defined with the Power and Ground nodes of the Schematic technology are combined into one network. This means, for example, that two arcs, each connected to a separate Ground node, appear on the same network regardless of their actual connectivity in the circuit.

As a debugging aid for power and ground networks, the command Show Power and Ground (in menu Tools / Network) shows the entire power and ground network. The Validate Power and Ground command checks all power and ground networks in the circuit. Any power or ground networks that are named according to the prefixes listed above must have the proper characteristics. If, for example, a power network is called "gnd007", then it will be flagged by this command. The command Repair Power and Ground changes the characteristics where necessary.

Many designs require multiple power and ground rails. Electric allows additional power and ground signals through the use of the Global node (see next Section).

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