Bridging the gap with greater accuracy

One of the few analogue device models for MOS transistors, the availability of MOS Model 9 should prove a welcome addition to the publlic domain, as it bridges a real gap. The model has proved its robustness, accuracy and good convergence in many challenging, as well as countless standard design tasks in the NXP worldwide design community. Furthermore, MOS Model 9 offers greater accuracy than the more complicated BSIM3, even though it has a smaller number of parameters. All important physical effects are incorporated in MOS Model 9. For example, body-effect for implanted substrate, drain-induced barrier lowering, channel-length modulation and avalanche multiplication. Noise and charge models are also available.

Effects modelled with MOS Model 9

• body effect for impanted substrate
• mobility reduction due to transversal field
• velocity saturation
• subthreshold region
• drain-induced barrier lowering
• static feedback
• channel-length modulation
• avalanche multiplication

Full-range scaling

The sound physics basis of MOS Model 9 is evidenced by the full-range geometrical scaling rules for these parameters, which have been verified on a series of IC processes down to 0.13 micron. Temperature dependency is also included in the scaling rules of the model.

Improving convergence and convenience

In the development of the model, a great deal of attention was paid to modelling far outside the work area of the transistor. This has the effect of improving the convergence behaviour of a simulator, and has been used for many years now, to the complete satisfaction of all concerned. MOS Model 9 has relatively few parameters which makes parameter determination very convenient and manageable. The parameters are independent of each other and can be unambiguously determined from the various operating regions of the transistor. Transitions between different operating regions are modelled smoothly. Users generally find that with one parameter set covering the whole geometry range of a process, they can work productively and with great flexibility.