Hi,
device models are considered proprietary by the foundries and are not published on the web. If you are registered at a university, you should be able to ask a lecturer for accessing the design kits installed on their servers. Alternatively, as suggests Marc, you can register with MOSIS or Europractice, but this is only possible as a university or company, not as an individual, I believe. So, if you want to do this design "undercover", you can still find some device models on the web:
- this is the EKV model of a generic 0.15um process
http://www.eecs.berkeley.edu/~zyzhang/ee290c/Hspice/CDR/cmos_15.txt- these are the generic models from J.Baker's book:
http://cmosedu.com/cmos1/book.htm- on this page some bipolar parameters:
http://www.seas.upenn.edu/~jan/spice/spice.models.htmlYou are right about the bipolar models, the vertical device you use in a standard CMOS process is not comparable in performance with the optimized bipolar transistor in a bipolar or BiCMOS process. However, as you are not going to integrate this design and you just want a device model with exponential characteristic, these should work too.
Notice all these models are Spice models, you have to add a language statement at the beginning if you use Spectre.
Paul