I try to implement a full adder circuit using square arrays.

Full adder

I've used Digital software to design it. Also I've tested it. It works fine.

But my implementation is quite different from the circuit shown by the lecturer.

full adder

As you'd see, to be able get correct results I switched the outputs (S and Cout)

Also as you'd recognise the layout of NFET gates are different.

Is the layout of NFET gates correct? Thanks.

Update: My temporarily solution is like this.

Temporarily solution

  • 3
    \$\begingroup\$ Look more carefully ... you haven't swapped anything. Or you've swapped everything. I don't know if it's correct but both designs are identical. \$\endgroup\$ – user_1818839 Sep 14 '20 at 20:40
  • 2
    \$\begingroup\$ Not only are S and COUT swapped, but the 0/1 of the muxes on the bottom also seems to be swapped (based on the location of the '0' label) \$\endgroup\$ – Justin Sep 14 '20 at 20:42
  • \$\begingroup\$ Thanks. If that's the case I should manually make a mux and try again. \$\endgroup\$ – Erdem Sep 14 '20 at 20:51
  • \$\begingroup\$ @Erdem The comment you have from Brian is right. They are the exact same thing. In Digital, check off the box on your MUXes that says "flip selector position". This places the selector on the same side as the "0" input so that it matches with your second picture. This will force you to move the connection FETs. Then move your S to the left and your Cout to the right. Once that is done, you'll see if you haven't already beforehand, that they are the same thing. \$\endgroup\$ – jonk Sep 14 '20 at 21:45
  • \$\begingroup\$ I've tried to flip selector position. But this tiime input gates are looking down output is on the top. If it was possible to mirror the component on horizontal axes. it would come to the desired position. \$\endgroup\$ – Erdem Sep 15 '20 at 9:37

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