Hello all, I'm trying to understand the 20V devices available in SKY130. From the documentation at readthedocs, the current driving parameters seems to be the ones pasted below. What's the difference between these 3 currents? did anyone design with the 20V devices already? And, in general, how can we check the meaning of the model output parameters in the tables?

These are just values measured from test structures. My guess is "L" means "linear (region)", "S" means "saturation (region)", and "5" is probably a measurement at 5V gate voltage. But if you don't know the test structure, the values are meaningless. You should be able to trust the SPICE device models.

Hello @User, thanks for the reply. I'm actually trying to find out the maximum current per channel width in high-voltage devices to implement a dcdc converter, do you know how to get this value? Or do you know who could know about this?

My take on that is that the maximum current in a MOSFET is usually not limited by the transistor itself, but by the wiring to the MOSFET, incl. maximum current per contact via. So my advice: See how much current the metals+vias can carry, then the MOSFET should be fine.

In my experience of DC/DC converters the driving factor is the specific on-resistance (mOhm mm^2) of the FET which tells you the area required for a given on-resistance. This allows you to compare apples to apples with different devices across process, voltage ratings etc. You can calculate the required on-resistance using the RMS current through the switching device and some constraint on dissipated power either from efficiency targets or temperature dissipation. In most cases the saturation current falls away and the on-resistance drives the decisions. Then of course the metal current density rules need to be obeyed during layout. In sky130 that's tricky because there is no metal current density rules but the 1 mA/um rule of thumb can be used.

I added estimates of the metal layer current density maximum values here: https://docs.google.com/spreadsheets/d/1oL6ldkQdLu-4FEQE0lX6BcgbqzYfNnd1XA8vERe0vpE/ at the bottom of the page "Layer Resistances and Capacitances". These values are based on the aluminum layer thicknesses. I don't know the equivalent values for titanium nitride, so I don't have a value for local interconnect, and I don't know the exact composition of their contacts, so I don't have values for the vias.

hello @User @User @User, thanks a lot for the great info here, I understand better the compromise now. I will probably come back with further questions if you don't mind!