does the SKY130 process support depletion mode fet

Question

Harald Pretl · Answer

There is an NMOS NVT available which has a Vth ~ 0V not exactly what you are looking for but close There is no MOS FET available with a negative Vth NMOS and positive Vth PMOS respectively

proppy · Answer

neat is that `sky130 fd pr nfet 05v0 nvt`

proppy · Answer

I didn t realize there was something between the enhanced and depleted variant

proppy · Answer

the cross section doesn t look that different from a regular FET

proppy · Answer

is the only difference in the size

proppy · Answer

oh it doesn t have that `Vt adjust implants` thingy too

proppy · Answer

that makes sense if the only difference is the Vt slightly smiling face

proppy · Answer

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Harald Pretl · Answer

Exactly the difference is the channel implant under the gate This influences the Vth The natural Vth NVT sit without additional implant in the well substrate

proppy · Answer

Does it trigger on Vg gt = Vs or 0 lt = Vg lt = Vs

proppy · Answer

I assumed the former but I wasn t 100 clear after reading <https en wikipedia org wiki Native transistor>

proppy · Answer

actually <https en wikipedia org wiki Threshold voltage Basic principles> makes it all clear slightly smiling face

Harald Pretl · Answer

Thanks for Wiki link on the native MOS FET didn t know that one exists slightly smiling face

proppy · Answer

those wikipedia pages are suprisingly good and accessible

proppy · Answer

I tried to simulate the native fet in an inverter circuit <https gist github com proppy dd2352e210b58e6c4b0c9deb84aef579> but it looks a bit weird i e the voltage doesn t go back to 0