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Reliable HICUM implementation in Eldo

Reliable HICUM implementation in Eldo. Mohamed Selim Device Modeling Team Mentor Graphics. HICUM Workshop, June . 2004. Overview. HICUM status in Eldo. Stability issues in the standard model. Enhancements done to improve stability. Current work done. Conclusion. Status.

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Reliable HICUM implementation in Eldo

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

  2. Overview • HICUM status in Eldo. • Stability issues in the standard model. • Enhancements done to improve stability. • Current work done. • Conclusion. HICUM in Eldo, June 2004

  3. Status • Model implemented since 1999 in Eldo v5.3_1.1. • The model accuracy was reviewed versus DEVICE simulator and some major accuracy issues had been resolved in Eldo v5.8_1.1, released 2001. • 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 . • Since then, no modifications were done in the standard model, hence in Eldo just minor bug fixes were done. HICUM in Eldo, June 2004

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

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

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

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

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

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

  10. Enhancements • 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. • All the testcases that showed convergence problems are working fine with the new modifications. HICUM in Eldo, June 2004

  11. Current Work • We are currently enhancing the speed of the HICUM model in Eldo. • This will be available in the AMS 2004.3 release. HICUM in Eldo, June 2004

  12. Conclusion • AMS 2004.2 (Eldo v6.3_2.1) which was released few weeks ago has a fully stable HICUM model with NO convergence issues. • 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. • 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. HICUM in Eldo, June 2004

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