Missing betaeff and ueff operating-point parameters in TSMC 28 nm HPCULL models

Hi everyone,

I’m working on MOSFET characterization using Cadence Virtuoso 6.1.8 and Spectre 20.1, where I need to extract operating-point parameters across a DC voltage sweep.

I noticed a difference between two TSMC 28 nm model libraries:

• CRN28HPCRF+ (tt)
• CRN28HPCULL (tt)

I tested the same NMOS testbench with both model libraries, using their respective TT corners.

With HPCRF+, I can retrieve gm, betaeff, and ueff from the DC sweep.

However, when I switch to HPCULL, gm is available, but betaeff and ueff are missing from the operating-point parameter list and cannot be retrieved.

I also tried explicitly saving these parameters using:

saveOpPoint("/M_0_1_0" ?operatingPoints "betaeff ueff")

But Spectre reports:

WARNING (SPECTRE-8059):

'betaeff' No such output parameter,

terminal, or internal node name.

A similar warning appears for ueff.

I would like to understand:

1. Is it expected for different TSMC 28 nm model libraries to expose different operating-point parameters?
2. Could this difference be related to the underlying compact model implementation?
3. Are there equivalent parameters for betaeff and ueff in HPCULL, or another way to retrieve this information?

Any suggestions would be appreciated.

Thanks!