Tristate Cells

015_cell : Tristate Cells

Minimum Required Versions: AccuCell 2.6.0.R, SmartSpice 4.6.2.R

This example explains the characterization and modeling options for a tristate inverter cell using the embedded SmartSpice SPICE engine to perform characterization.

The .cfg commands CUR_CUTOFF_THR, GDS_CUTOFF_THR, TRISTATE_METHOD are tristate specific.

TRISTATE_METHOD selects between the characterization methods of gds the source-drain conductance and current use of a second competing tristate and its effect on the voltage of the bus creating a current sink.

CUR_CUTOFF_THR specifies the on/off current threshold ratio for the TRISTATE_METHOD current option.

GDS_CUTOFF_THR specifies the on/off source-drain device conductance ratio for the TRISTATE_METHOD gds option.

The choice of method and the threshold ratio value selected impact the measured timing for tristate cells when coming out of and going into the "Z" tristate condition.