To state it clearly: OpenMP is installed inside the model equations of a particular model. It is available in BSIM3 versions 3.3.0 and 3.2.4, but not in any other BSIM3 model, in BSIM4 versions 4.5, 4.6.5, 4.7 or 4.8, but not in any other BSIM4 model, and in B4SOI, version 4.4, not in any other SOI model. Older parameter files of version 4.6.x (x any number up to 5) are accepted, you have to check for compatibility.

Under Linux you may run

./autogen.sh

./configure ... --enable-openmp

make install

The same has been tested under MS Windows with CYGWIN and MINGW as well and delivers similar results.

Under MS Windows with Visual Studio Professional the preprocessor flag USE_OMP, and the /openmp flag in Visual Studio are enabled by default. Visual Studio 2015 or 2017 offer OpenMP support inherently.

The number of threads has to be set manually by placing

set num_threads=4

into spinit or .spiceinit or in the control section of the SPICE input file. If OpenMP is enabled, but num_threads not set, a default value num_threads=2 is set internally.

If you simulate a circuit, please keep in mind to select BSIM3 (levels 8, 49) version 3.2.4 or 3.3.0 (11.2.10), by placing this version number into your parameter files, BSIM4 (levels 14,

54. version 4.5, 4.6.5, 4.7 or 4.8 (11.2.11), or B4SOI (levels 10, 58) version 4.4 (11.2.13). All other transistor models run as usual (without multithreading support).

If you run ./configure without --enable-openmp (or without USE_OMP preprocessor flag under MS Windows), you will get only the standard, not paralleled BSIM3 and BSIM4 models, as has been available from Berkeley. If OpenMP is selected and the number of threads set to 1, there will be only a very slight CPU time disadvantage (typ. 3%) compared to the old, non OpenMP build.