Circuit Design: Know It All

Chapter 10

Combinational Logic Design

Ian Grout

10.1 Introduction

Using the previous ideas, combinational logic circuits can be combined using either the first canonical form (sum of products) or the second canonical form (product of sums). However, in this text only the first canonical form will be considered, taking into account logic level 0 or 1 and propagation (time) delays in the cells.

Within a logic gate is an analog circuit consisting of transistors—either bipolar, using NPN and PNP bipolar junction transistors, or CMOS (complementary metal-oxide semiconductor), using N-channel MOS and P-channel MOS transistors. Logic gates in CMOS are of three different circuit architectures at the transistor level [Ref. 10.1]: static CMOS, dynamic CMOS, ...