Any Suggestions on ring oscillator verification

Hello all,

I am a little lost. I received a spectre model of the 0.35um Mixed
Mode proces from Mosis (really TSMC's 3.3V/5V Mixed Signal process) and
was trying to verify the ring oscillator values listed in spice model
document. I thought a quick verification of the ring oscillator table
would be a good double check of the schematic entry to simulation flow.
Unfortunately, the values I get and the values listed is about 40% off!
I am a little puzzled and perhaps it is my understanding of
AD,AS,PD,PS and the relavance to hdif and ld. Or maybe something more
fundamental?

I am using ic5.0.33 spectre simulator and have connected n(odd)
inverter strings that match the description (including w and l for nmos
and pmos devices) in the document. Supply was set to 3.3V, temp set to
25 degrees C, initial conditioned a single inverter input/output node
to 0, and ran a transient simulation for 40ns. I have tried both
specifing AD, AS, PD and PS and and not specifying them and got
similiar errors.

given, then it defaults to the hdif parameter, if hdif is not specified
then it goes to the ld parameter, and finally gives 0 if no ld
parameter is defined. Is my understanding correct? Incidentally, the
document specifies that hdif, xw and xl was modified to get the results
listed, which I also did in the model file. I am assuuming the hdif
comment indicates that they did not specify AD,AS,PD,AS.

Because the only item provided was the model file, I used the analogLib
nmos4 and pmos4 symbols and just changed the w,l, and model name to
suite.

Any help would be greatly appreciated and thank you for time in reading
this.

sam