How are logic chips (AND/OR/NAND/etc) actually built to work like their chosen logic gate?


Like with an AND gate I understand how it works in that an input of 1 AND 1 make an output of 1, but how do the logic chips actually perform the function? How would you build a logic gate without using logic chips?

In: Engineering

The basic building block of electrical/electronic gates is the transistor. You can think of a transistor as an electrically operated switch. This switch has an input, output and a “switch” (also an input). If the switch is “on” it connects the input to the output, if the switch is “off” the input is disconnected from the output.

By differing configurations of this switch (several transistors connected in different circuit patterns), all logical gates can be constructed.

The basic building block is a transistor, which is basically just a little switch with three connections: the input, the output, and the gate. If the gate value is 1, the output value is the same as the input. If the gate value is 0, the output value is 0.

An AND gate can be made with two transistors. You connect each of the inputs to the gate of one of the transistors. One transistor has the input connected to a constant 1 source and the output connected to the input of the other transistor. The other transistor’s output is the output of the AND gate. As long as both transistors are switched on, the 1 value will flow through and out to the output. If either is switched off, the output will be 0. This video might help you out. Demonstrates the actual construction of a chip.