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My plan is to build a discrete CMOS inverter(just out of curiosity) out of two complementary MOSFETS. Hence, I am currently looking for a nice pair of complementary MOSFETS, which is quite hard, because there is such an enormous variety. Furthermore, it is really important, that there is a spice model available for the MOSFET chip.

Do you think that this chip is the "right" one(would do a good job)? https://www.fairchildsemi.com/datasheets/FD/FDY4000CZ.pdf

Best regards, Pearson

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I would suggest a much older chip, the CD4007. It's designed to be used in exactly the way you describe, to make CMOS inverters.

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  • \$\begingroup\$ I am sorry that I forgot to mention that I also need a spice model for the MOSFETS, and I can't find a model for the CD4007. Where would you see the problems with my chip? \$\endgroup\$
    – Pearson
    Dec 7, 2014 at 10:02
  • \$\begingroup\$ @Pearson Maybe you could edit the question and add that info? I don't really see a problem with the chip you suggested, but it is a power MOSFET pair, as opposed to a signal MOSFET pair. It's meant for H-bridge-type ciruits, I think. \$\endgroup\$ Dec 7, 2014 at 10:03
  • \$\begingroup\$ There are models out there for the CD4007 - that would be excellent choice if the models are accurate enough for your purposes. \$\endgroup\$ Dec 7, 2014 at 22:05
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Sure, that chip could work. But you'd need 3 of them in a row since using only one would allow the transistors in the output stage to remain in their ohmic region, causing the device to acts more as an amplifier than an inverter.

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  • \$\begingroup\$ Could you please be so kind and explain why exactly this would happen? I am familiar with the concept of the inverter, but right now I don't understand why it would remain in the ohmic region. While simulation this didn't happen ;). thx \$\endgroup\$
    – Pearson
    Dec 7, 2014 at 10:17
  • \$\begingroup\$ You won't see it if you have fast transitions between L and H or vice versa. Slow down the input waveform. \$\endgroup\$ Dec 7, 2014 at 10:20
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The main issue I can see is that you'll likely see some fairly large current spikes during the transitions when both MOSFETs are on. If that's okay with you, party on.

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  • \$\begingroup\$ So you would probably recommend to use MOSFETS with higher on-resistance? Could you maybe recommend one :) ? \$\endgroup\$
    – Pearson
    Dec 7, 2014 at 12:00
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    \$\begingroup\$ 2n7000 and BSS84(?)- can't check right now stewardess is giving me evil eye. \$\endgroup\$ Dec 7, 2014 at 13:45
  • \$\begingroup\$ There's a question here: electronics.stackexchange.com/questions/108388/… that shows the P-channel FET as a BS250. \$\endgroup\$ Dec 7, 2014 at 14:50
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    \$\begingroup\$ BSS84 is the one I was thinking of, but that's a complement of the 2N7002 SMT version of the 2N7000. B$250 is more expensive. \$\endgroup\$ Dec 7, 2014 at 21:59

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