1. ECEN 248: INTRODUCTION TO DIGITAL SYSTEMS DESIGN Lecture 5 Dr. Shi Dept. of Electrical and Computer Engineering

2. How are Gates Implemented?  By Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET)  PMOS if source/drain are p-type semiconductor  NMOS if source/drain are n-type semiconductor  CMOS (complementary MOS) GATE SOURCEDRAIN Oxide  5 nm Gate length  20 nm Hair=0.1mm 1000um=1mm 1000nm=1um

3. NMOS and PMOS

4. CMOS NOT gate

5. CMOS NAND Gate Pull up: Pull down:

6. CMOS NOR Gate Pull up: Pull down:

7. Example: Logic Realization  Realize the following logic: Pull up Pull down:

8. Negative Logic

9. NMOS Gates

10. NOT Gate

11. NAND and NOR Gates

12. Fan-in Fan-out and Buffers

13. High Fan in  Fan-in: Number of inputs  Fan-out = Number of outputs  This gate has large fan in  Large delay

14. High Fan out: Large switching time

15. Buffer  Each buffer can drive an output.  Just two inverters in series.

16. Tri-State Buffer

17. Transmission Gate

18. Example XOR