Maybe it's a font issue, but it looks to me like you swept the inverter's
input voltage from 0 to 1 V. If that is the case, it could be that the
input is below the turn-on threshold of the N-MOSFET. Try driving the
inverter input voltage higher and see if you get a low on the inverter output.
The simplified MOSFET transfer function is typically Id = g * (Vgs -
Vth)^2, where:
Id = drain current (flows from drain to source***)
g = transconductance (see datasheet)
Vgs = voltage from gate to source
Vth = gate turn-on threshold voltage (see datasheet)
***assuming conventional current flow, see my other recent emails on this
topic.
The equation is valid for enhancement-mode MOSFETs and for Vgs >= Vth.
When Vgs < Vth, the only drain current flowing will be leakage (Idss, see
datasheet), since the MOSFET is turned off.
Is that your real name, Tasting Fan ? If not, tell us your real name.
Nicknames are fun, but it's good to know who we are really communicating with.
I use my real name here, it's less embarassing than my nickname(s) ;-)
Best regards,
Ivan Baggett
Bagotronix Inc.
website: www.bagotronix.com
tastingfan tastingfan wrote:
Hi,
I want to simulate a CMOS-Inverter with Protel 2004. I have two MOSFETs
(MOSFET-P and MOSFET-N), one power supply of 3.3V and one impulse generator
which gives out rectangular waves of 1 kHz. But the result is wrong! The input
has a range from 0V ¨C 1V, that¡¯s OK. But the output only from 3.072 to
3.300V. Why is it not zero?
Best Regards
Tasting_fan
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