MOS Models for circuit distortion analysis

I am trying to do distortion analysis of a circuit
using a MOSFET in linear region. If I use a
BSIM3V3 model the results are incorrect because
of discontinuity in the high-order
derivatives of Id vs. vds characteristic around
Vds=0. This is a known problem. (see for example,
paper by Y. Tsividis, K. Suyama, IEEE Jl. Solid-State
Circuits, March 1994).

My question is: has anybody has been able to overcome
this problem? I am aware of EKV model but do not
have access to a practical model derived from
characterizations that I could use.

Thanks,
Subhajit Sen
(PS: Pls. also reply to [EMAIL PROTECTED]).