EE141 Spring 2003 Discussion 1. Tips for Using SPICE. Discussion Operation. Discussion talks about technical details that could help understanding the class material Tips in using the circuit design tools Advices on preparing for the projects and homeworks
Tips for Using SPICE
Ke’s session: Wed. 2-3pm, Cory 197
Lynn’s session: Tue. 1:30-2:30pm, Cory 197
– includes a file, usually a model file, or a subcircuit file
– sets simulation options, e.g .OPTION POST=2
– but allows another simulation to be performed with the same setup except the changes that follow the .ALTER statement
– marks the end of an input file
– when SPICE can’t find solution to the circuit calculation with the input control and circuit setup
– *ERROR* : NO CONVERGENCE IN DC ANALYSIS
– *ERROR* : INTERNAL TIME STEP TOO SMALL IN TRANSIENT ANALYSIS
– In digital circuit simulation, CHECK THE CIRCUIT CONNECTIONS.
– In analog circuit simulation, do hand analysis / change control options / simplify models …
– This often happens with floating MOSFET gates. Just add a resistor between the node and ground, or use the .IC or .NODESET commands to create an initial condition. Be warned, however, that .NODESET and .IC can cause convergence problems.
– Sometimes a transient analysis shows a “ringing” or oscillation that shouldn’t be there. This can often be solved by reducing the maximum time step or using slower rise and fall times for independent sources.