ESD Verification
Below two examples from our automated test suite showcasing how our approach reverse solving the HBM model math as elaborated in Physics-Based_Wire_Sizing_for_I/O_Pad_Cells actually leads to simulation results in ngspice which show that our ESD diodes we chose actually protect our internal circuitry.
Oh wow. When you solve Ohm's law in one direction and then the other, you end up with the current you originally have defined at a certain voltage. Who would have thought this... anyway. Here some examples.
After running
./tests/test_all_padcells.sh visual
you end up with a folder called "generated_output"
We're looking at "generated_output/SG13G2/padcell/1.2V" and "generated_output/SG13G2/padcell/3.3V" here as examples
The IHP SG13G2 @ 1.2V case
Comparing those two you will notice that the pad with the lower operational voltage needs more area.
While at first counter intuitive, this is because we're not dealing with Ohm's law here but with solid state physics, such as hot carriers and the such.
The thermal budget also plays a role but not as much as electron migration and so.
HBM ESD Dissipation
ESD Waveforms
HBM ESD Zoomed In
The IHP SG13G2 @ 3.3V case
Lets say we ran and get this test case for a 20mA pad cell for IHP's SG13G2 process for a voltage of 3.3V
Then you end up with this thing
