anyone working on 10V+ FETs.?
May be i'm wrong. Ho...
# sky130p
Pritesh Ps
12/03/2022, 2:49 PManyone working on 10V+ FETs.?
May be i'm wrong. However, I tried 10v5 and 16v as per docs the max gate voltage is 5.5V for both. However, i made simple inverter to test it individually. and i noticed that even as docs states providing 5V Vgs doesn't inverts fully. Around 10v at the input in inverter ckt of 10v5 is needed to inverter it fully. same case for 16V, around14.5V is needed. and for inverter ckt made of 20v FET's input voltages nearly 20v at the gate is needed. so, why 5v at the Vgs is mentioned as max..
one can see in images, and understand its not turning OFF completely without giving more than mentioned Vgs.
https://skywater-pdk.readthedocs.io/en/main/rules/device-details.html#v-10-5v-nmos-fet
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Arman Avetisyan
12/03/2022, 2:53 PMYou cant really close the pmos with 5V, right?
Arman Avetisyan
12/03/2022, 2:54 PMI wonder why would you need an inverter for 10V?
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Pritesh Ps
12/03/2022, 2:55 PMin case of 10v5 FET's, Vgs = 5.3V a bit less than max rated (Vgs=5.5V) still.
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Boris Murmann
12/03/2022, 2:55 PMThis is not a legitimate high voltage circuit. The P and N need separate controls to keep the voltage across the thin gate oxide below 5V (You cannot simply smack a P and NMOS together with a 14V supply). Have a look the literature.
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Pritesh Ps
12/03/2022, 2:59 PM@Boris Murmann: like in case of 16V FET's, i have to drive them individually with 5V as Vgs, right?
Sorry i don't understand why not, that's a very basic inverter circuit and being used almost everywhere. care to enlighten me.
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Arman Avetisyan
12/03/2022, 3:04 PMyou need to use lv2hv schematic. So that only you will need to contol only the NMOS, which you CAN control using only ground and the input signal.
Arman Avetisyan
12/03/2022, 3:06 PMThe pmos gate needs to be VDD-Vth to close the pmos, which you cant simply get out of thin air with schematic you used.
Arman Avetisyan
12/03/2022, 3:08 PMThe MN1 can be opened with 5v vdd and the same for MN2
MP1 cant be controlled so we use the schematic above to pull it between ground and the 16V
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Pritesh Ps
12/03/2022, 3:09 PM@Arman Avetisyan thank you for providing with the source.
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Arman Avetisyan
12/03/2022, 3:10 PMyou cant control PMOS without level shifter
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Boris Murmann
12/03/2022, 3:10 PMYou also cannot use this level shifter with 16 V. The oxide of the PMOS will break (Think about it). I recommend that you read up on HV circuits using a basic Google search.
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Arman Avetisyan
12/03/2022, 3:11 PMoh wait, yeah. My bad. This only works if gate and drain source can withstand that voltage
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Pritesh Ps
12/03/2022, 3:17 PM@Arman Avetisyan Actually, i wasn't making a LEVEL SHIFTER or similar. I opened a cmos book and there's one basic INVERTER ckt to estimate tpd and tcd and that's it.
I wonder how this is related to LEVEL Shifter.
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Luis Henrique Rodovalho
12/03/2022, 6:13 PMThis is the kind of level shifter that uses this kind of transistor, with different max voltages for VGS and VDS.