CCS Timing Characterization

007_cell : CCS Timing Characterization

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

This example explains the use of AccuCell's Composite-Current-Source (CCS) Timing characterization options for creating CCS Timing models for a simple inverter cell using the embedded SmartSpice SPICE engine to perform characterization.

In the case of CCS timing models, the reported extended format Liberty data also includes current waveforms for each of these rather than just a single time crossing or energy use value. In addition the CCS modeling includes additional details related to capacitance effects on input pins instead of just one single value (or a pair of values). This format can be selected by specifying CCS_TIMING 1 in the Cell_EX7.cfg file. Additionally, CCS_CURRENT_POINTS <num_of_points> can be specified in the Cell_EX7.cfg file to control the number of current points to generate in the CCS format model.

An example of the format can be found in Cell_EX7_library_sps.lib. An inverter has been chosen to minimize the volume of data this new format generates but provides a good basic understanding for more complex cells. The CCS format is an extension of NLDM. As such, new CCS data tables ONLY exist for input pin capacitance and output timing delay sections.

NOTE: At this time SmartView can not plot CCS data sections. To visualize this data use any spreadsheet program to import the ascii data for graph generation.