Digital Logic Structures: Chapter 3 COMP 2610 Dr. James Money COMP

Logic Gates One level up from the transistor is a logic gate We use individual MOS transistors to construct our basic logic structures We will consider AND, OR, and NOT gates

The NOT Gate (Inverter) To construct a NOT gate, we need – One n-type transistor – One p-type transistor These are connected together to obtain the NOT gate This is sometimes called an inverter

The NOT Gate (Inverter) InOut 0 V2.9 V 0 V InOut Volts 0 Volts

The NOT Gate (Inverter)

OR and NOR Gates ABC 0 V 2.9 V 0 V2.9 V0 V 2.9 V0 V 2.9 V 0 V

OR and NOR Gates ABC = A NOR B

OR and NOR Gates How to we obtain the OR gate now? We chain the NOT gate to the end of the NOR gate NOT (NOR) = OR We do this b/c it is cheaper to produce NOT type gates versus regular ones

OR and NOR Gates OR Gate