1. Digital Logic Structures: Chapter 3 COMP 2610 Dr. James Money COMP 2610 1

2. 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

3. 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

4. The NOT Gate (Inverter) InOut 0 V2.9 V 0 V InOut 01 10 2.9 Volts 0 Volts

5. The NOT Gate (Inverter)

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

7. OR and NOR Gates ABC = A NOR B 001 010 100 110

8. 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

9. OR and NOR Gates OR Gate