Electronic – Why are NAND Gates cheap


In my digital electronics labs and lectures we are told to try and make things from NAND gates, because they are the cheapest kind of gate available to buy. Why is this? Why isn't an OR/AND gate the cheapest to buy?

Best Answer

NAND gates are cheap because there are so many of them lying around from the 1980s.

Seriously though, a NAND gate is about the simplest logic gate. You can think of it as a multi-input inverter. Electrically, that's exactly what TTL NAND gates are. Each input is just another emitter added to the input transistor. The rest of the circuit is just a inverter. It's different in CMOS, but a NAND gate is still very simple.

Since the chips require few transistors, they can be small, which allows lots of them per silicon wafer, which makes them cheap.