Hi @Stefan Schippers Can I use nfet_01v8 with a supply voltage of 3.3V? I am wondering because when I simulated a circuit including a nfet_01v8 transistor, the testbench run successfully well without any notification of avoiding using large supply voltage in Xschem. Does the nfet_01v8 transistor operate fine while using a supply voltage of 3.3V?

@Ahmed Reda I am not aware of any spice/verilog simulator that detects EOS (electrical overstress) conditions that you are referring to. Industry standard tools used to detect these errors include PERC tools by Calibre (Seimens), Synopsys, and Cadence and InsightEDA’s Insight Analyzer. My open source CVC_RV can also be used to detect these errors. https://github.com/d-m-bailey/cvc.git

@Mitch Bailey Yes, I have been using calibre and cadence which can inform breakdown when applying a large power supply. I will try to use the CVC-tool. Excuse me, I have two more questions,1- Is there available data for - max. VDS, Max. VGS, and Max IDS for nfet_01v8 and nfet_01v8_lvt. 2- In PDK, https://skywater-pdk.readthedocs.io/en/main/rules/device-details.html, I found the Operating Voltages where SPICE models are valid at VDS=0:1.95V and VGS=0:1.95V. Does it mean maximum VGS=1.95 and maximum VDS=1.95?right? Thanks

@Ahmed Reda I’m not sure of the actual max Vgs/Vds. CVC_RV only has very simple propagation and does not accurately calculate analog voltages. For most EOS checks, I just use the intended voltage domain as the max. The model settings are correlated with the voltage settings, so in the power file you can set

vccd1 power 1.8

and then in the model file

MN nfet_01v8 Vgs=vccd1

The max nominal voltage as the name of the device suggests is 1.8V. Taking into acount supply tolerance this leads to a maximum of 1.95V. For more info: https://skywater-pdk.readthedocs.io/en/main/rules/device-details.html Simulator does not issue warnings for excessive voltage, unless you set up specific SOA checks. Using drain voltages beyond 2V usually will lead to huge current injection into the substrate, hot electrons generation and transistor permanent degradation. I would also say that models are not reliable outside the allowed operating range. Just avoid using transistors out of their maximum range.

@Mitch Bailey @Stefan Schippers Thanks. I got it.