1. Reliable HICUM implementation in Eldo Mohamed Selim Device Modeling Team Mentor Graphics HICUM Workshop, June. 2004

2. Copyright ©1999-2001, Mentor Graphics. 2 HICUM in Eldo, June 2004 Overview n HICUM status in Eldo. n Stability issues in the standard model. n Enhancements done to improve stability. n Current work done. n Conclusion.

3. Copyright ©1999-2001, Mentor Graphics. 3 HICUM in Eldo, June 2004 Status n Model implemented since 1999 in Eldo v5.3_1.1. n The model accuracy was reviewed versus DEVICE simulator and some major accuracy issues had been resolved in Eldo v5.8_1.1, released 2001. n In the 2001 workshop, ST presented a comparison between different commercial simulators showing that Eldo had the best implementation of the model for the DC results. n Since then, no modifications were done in the standard model, hence in Eldo just minor bug fixes were done.

4. Copyright ©1999-2001, Mentor Graphics. 4 HICUM in Eldo, June 2004 Stability Issues n Currents, Charges and their derivatives (conductances and capacitances) are needed from model for proper simulation for all types of analysis; DC, AC and TRANSIENT. n Convergence problems were seen using the standard model implemented in Eldo due to missing or incorrect derivatives (from the numerical point of view). n The standard model focuses on DC and small signal behavior mainly, many derivatives were not taken into account.

5. Copyright ©1999-2001, Mentor Graphics. 5 HICUM in Eldo, June 2004 Stability Issues n 4 Major points of instability exist: — Self heating derivatives. — Diffusion capacitance modeling. — NQS model. — RBI dependencies. n Some modifications in the existing derivatives were done and some derivatives were added to the standard model in Eldo to enhance the stability. n In the following slide a summary of the work done will be presented.

6. Copyright ©1999-2001, Mentor Graphics. 6 HICUM in Eldo, June 2004 Enhancements n Diode junction currents derivatives w.r.t. self heating (thermal) voltage. n Avalanche current derivative w.r.t. self heating (thermal) voltage. n RBI derivatives w.r.t. VBE and VCE. n Changing the expression for CDCI calculation. n Adding the new derivative of QDEI w.r.t. VCEI. n Applying the NQS effect on all derivatives of ITF (forward transfer current) and QDEI (base emitter depletion charge).

7. Copyright ©1999-2001, Mentor Graphics. 7 HICUM in Eldo, June 2004 Enhancements n These added features are added in AMS2004.2 release corresponding to Eldo v6.3_2.1. n A new parameter called AMSVER is added. n It can take 2 values. — 2004.1 -> Standard AC results are maintained. — 2004.2 -> AC results are changed (default). n For both values of AMSVER, the newly added derivatives are always used used to enhance convergence for DC and TRANSIENT analysis.

8. Copyright ©1999-2001, Mentor Graphics. 8 HICUM in Eldo, June 2004 Enhancements 1e12H 0.01F 0.5v DC 1.0v DC V1 = 1mv AC Temp = 27 FREQ = 10MHz, 100MHz, 1 GHz, 10 GHz AC setup I2

9. Copyright ©1999-2001, Mentor Graphics. 9 HICUM in Eldo, June 2004 Enhancements 1e12H 0.01F 0.5v DC 1.0v DC V1 = sinusoidal source with peak value 1mv, frequency = FREQ Temp = 27 FREQ = 10MHz, 100MHz, 1 GHz, 10 GHz TRANSIENT setup I2

10. Copyright ©1999-2001, Mentor Graphics. 10 HICUM in Eldo, June 2004 Enhancements n From the results the AC values with AMSVER = 2004.2 match those obtained from the TRANSIENT analysis and they are both different from the standard AC results with AMSVER = 2004.1. n All the testcases that showed convergence problems are working fine with the new modifications.

11. Copyright ©1999-2001, Mentor Graphics. 11 HICUM in Eldo, June 2004 Current Work n We are currently enhancing the speed of the HICUM model in Eldo. n This will be available in the AMS 2004.3 release.

12. Copyright ©1999-2001, Mentor Graphics. 12 HICUM in Eldo, June 2004 Conclusion n AMS 2004.2 (Eldo v6.3_2.1) which was released few weeks ago has a fully stable HICUM model with NO convergence issues. n AMS 2004.3 (Eldo v6.4_1.1) planned to be released by the end of the year will have the speed enhanced version of the model. n MG is always looking to keep the models in the very best shape from both accuracy compared to standard models point of view and model speed.

13. Copyright ©1999-2001, Mentor Graphics. 13 HICUM in Eldo, June 2004