we will examine the static and dynamic characteristics of various combinational MOS logic circuits. It will be seen that many of the basic principles used in the design and analysis of MOS inverters in next Chapters we can be directly applied to combinational logic circuits as well.
The first major class of combinational logic circuits to be presented in this chapter is the nMOS depletion-load gates. Our purpose for including nMOS depletion-load circuits here is mainly pedagogical, to emphasize the load concept, which is still being widely used in many areas in digital circuit design. We Will examine simple circuit configurations such as two-input NAND and NOR gates and then expand our analysis to more general cases of multiple-input circuit structures. Next, the CMOS logic circuits will be presented in a similar fashion. We will stress the similarities and differences between the nMOS depletion-load logic and CMOS logic circuits and point out the advantages of CMOS gates with examples. The design of complex logic gates, which allows the realization of complex Boolean functions of multiple variables, will be examined in detail. Finally, we will devote the last section to CMOS transmission gates and to transmission gate (TG) logic circuits.