Specifications

v
Using Subcircuits 49
A Simple Subcircuit Example 50
Subcircuit Primitive Type 52
Port Interface 52
Creating a Subcircuit—Top–Down 55
Creating a Subcircuit—Bottom–Up 57
4
Simulation 59
General Information on Simulation
59
Type of Simulation 59
Simulation Memory Usage 60
Time Units 60
Signal Simulation Characteristics
61
Signal States 61
Stuck–At Levels 64
Resolution of Multiple Device Outputs
65
Resistive vs. Forcing Drive 66
Signal Probe Tool 66
Busses 68
Bus Pins 68
Device Simulation Characteristics
69
Device and Pin Delay 69
Device Storage State 71
Input Signal Values 72
Device Pin Types 72
Device Pin Inversion 72
Simulation Clearing and
Initialization 74
The Clear Simulation Operation 74
The Clear Unknowns Operation 74
Setting Initial Values 75
Schematic Simulation Issues 76
Working With Subcircuit Devices 76
Power and Ground Connectors 80
Special Signal Names 0 and 1 81
Simulation Models 81
Primitive Devices on the Schematic 82
Simulation Pseudo–Devices 82
5
The Timing and Simulator Tools 83
The Timing Window 83
Displaying Signals in the Timing
Window 84
Adding a Signal Trace 84
Removing a Signal Trace 84
Repositioning Traces 85
LW Reference.bk Page v Monday, December 15, 2003 5:59 PM