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I have designed a circuit using a combination of NAND, NOT, AND and OR gates: logical circuit

I know how to build this circuit with MOSFET using CMOS technology but it requires 18 MOSFET. I would like to know how can I build the same circuit using an integrated circuit in order to reduce its size: physical circuit

I looked at some catalogs of electronics components and I didn't find any integrated circuit that embeds these four gates in one chip.

Does this kind of integrated circuit exists? If yes, how can I easily find them? If no, how can I reduce the size of my circuit?

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3 Answers 3

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Does this kind of integrated circuit exists?

No they don't. But notice that your inverter can be made of a second NAND gate by tying the inputs together. That eliminates one gate type.

enter image description here

Now, can you make the whole circuit out of NAND gates? Yes. All logic functions can be done with NAND. Here's an OR gate.

enter image description here

You can find the complete set in Wikipedia's NAND logic.

The result may use more gates than your original but it should use less chips (not "ships"). Look out for opportunities to eliminate gates. Do you need your inverter anymore if the B input of the OR gate also has an inverter? (I'll leave you to work out that puzzle.)

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  • \$\begingroup\$ I probably need to be careful about voicing my disagreement with your direct answer to his question. If I disagree too stridently, somebody might accuse me of coming from one of those ill-mannered places like Fidonet. :-) \$\endgroup\$ Oct 18, 2020 at 9:54
  • \$\begingroup\$ Thanks, Jerry. I can usually spot a homework question. Maybe I missed one here. I think I've left plenty of work for the OP though. \$\endgroup\$
    – Transistor
    Oct 18, 2020 at 10:57
  • \$\begingroup\$ I didn't mean it was wrong to answer directly. I just (sort of) disagree with the "No they don't." \$\endgroup\$ Oct 18, 2020 at 15:09
  • \$\begingroup\$ No problem, @Jerry. I've certainly never seen a chip with an inverter, a NAND, an AND and an OR in the one package. I'm assuming standard logic families though. \$\endgroup\$
    – Transistor
    Oct 18, 2020 at 15:12
  • \$\begingroup\$ True, but as I pointed out in my answer, a quad multiplexer is pretty common. \$\endgroup\$ Oct 18, 2020 at 15:13
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Following Transistor's answer, you can do it in a 7400 (74HC00 or whatever).

Starting with:

enter image description here

First convert the OR gate into a NAND, with an inverter on each input. This actually REDUCES the gate count because you migrate the external inverter into one of the NAND inputs.

Next convert the AND into a NAND with an inverter on the output. (Which brings the gate count back to 4)

Recognising we need to feed back the AND output via an inverter into the OR gate ... just use the NAND gate and eliminate both inverters.

Giving...

schematic

simulate this circuit – Schematic created using CircuitLab

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I looked at some catalogs of electronics components and I didn't find any integrated circuit that embeds these four gates in one [c]hip. Does this kind of integrated circuit exists?

Although it's not immediately apparent, yes they actually do sell such things. They're called multiplexers. You can wire up a multiplexer to act as any of the standard gate types (AND, OR, NOT, etc.)

It's pretty easy to find a quad 2:1 multiplexer chip, and that one chip should be enough to implement all the logic you've shown (and if you're careful, you'll probably even have one multiplexer left over).

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