6T SRAM SEU Simulation using SPICE only

radex16.in : 6T SRAM SEU Simulation using SPICE only

Requires: SmartSpice
Minimum Versions: SmartSpice 4.19.27.C

This example is a variant of radex14, where instead simulating the drain current response from an SEU strike using TCAD, and then importing this SEU data into a SmartSpice simulation, here we use an internal SmartSpice algorithm to calculate the total track charge created by the strike which is then converted into current time pairs internally at a specified device node and time.

The obvious advantage of using Spice to calculate the SEU track charge versus time, instead of using TCAD, is simulation speed. The downside is that the calculation is a worst case calculation, since it is assumed that all of the generated charge is actually collected by the device node, which is not usually the case. In reality, the actual fraction of charge collected depends on strike angle and strike location and whether any carrier multiplication occurs from high electric fields and internal gain etc.

The SEU event is struck at the same nMOS drain node, in the same SRAM circuit as in radex14 example, and with the same Linear Energy Transfer value of unity, which is now set in the .PARAM DLET=1 statement. The total charge in the charge track is calculated by integrating over the SEU track length, which is set by the .PARAM F_LENGTH=0.5u statement. Other timing parameters are also set on .PARAM statement lines.

For simulation method comparisons, the SRAM operation point is set to it's low power configuration with an applied supply voltage of 0.85 volts, which represents the state of highest sensitivity to being upset by a single event.

To load and run this example, select the Load button in DeckBuild > Examples. This will copy the input file and any support files to your current working directory. Select the Run button in DeckBuild to execute the example.