Transistor characterization

The transistor characterization consists of 2 main steps: characterization and query.

Creating the characterization database

This step characterizes a fixed sized transistor in 3 steps:

DC sweep: Run a DC sweep on a diode connected transistor to find vgs_min and vgs_max where the drain current is within some specified range ibias_min and ibias_max. This is essentially finding the vgs range when the transistor is “on”.
s parameter sweep: Run a multidimensional SP sweep across vgs, vds, vbs to compute the small signal parameters like gm, various parasitic caps (cgg, cgs, cgd, etc).
noise sweep: This estimates the thermal noise factor gamma from the total integrated noise. This is an approximation, and is valid only if the min frequency of the noise integration is above the frequency corner for flicker noise.

$ ./meas_cell.sh data/bag3_testbenches/specs_mos_char/nch_*.yaml
$ ./meas_cell.sh data/bag3_testbenches/specs_mos_char/pch_*.yaml

Run with -x to characterize the extracted transistor instead of schematic only.

At the end of the characterization, a database is created in the specified root_dir.

This step queries the small signal parameters per finger of the pre-characterized transistor at the desired bias point

$ ./run_bag.sh bag3_testbenches/run_scripts/test_mos_char.py data/bag3_testbenches/specs_mos_char/test_char.yaml