Skip to Content
Introduction to Digital Systems: Modeling, Synthesis, and Simulation Using VHDL
book

Introduction to Digital Systems: Modeling, Synthesis, and Simulation Using VHDL

by Mohammed Ferdjallah
July 2011
Intermediate to advanced content levelIntermediate to advanced
225 pages
6h 22m
English
Wiley
Content preview from Introduction to Digital Systems: Modeling, Synthesis, and Simulation Using VHDL

5.6 CMOS LOGIC NETWORKS

Design of logic networks using integrated transistors is an extensive discipline referred to as VLSI technology. Physical aspects of transistors play a major role in the layout of logic gates. VLSI technology is beyond our scope here. Nonetheless, the design concepts illustrated in Section 5.5 can be used to design integrated logic gates using CMOS transistors without exploring their practical aspects in detail. To understand how PMOS and NMOS transistors can be interconnected to realize a logic function, we analyze the CMOS logic circuit in Figure 5.10. We describe the logic function of the circuit by determining the state of each PMOS and NMOS transistor as the input voltages change according to the truth table.

An NMOS transistor is off when its input gate voltage is equal to 0 V, and it is on when its input gate voltage is equal to 5 V. A PMOS transistor is off when its input gate voltage is equal to 5 V, and it is on when its input gate voltage is equal to 0 V. Using these properties of NMOS and PMOS transistors, one should be able to determine the state of each transistor in the logic circuit. The truth table of the integrated logic circuit is also shown in Figure 5.11.

Using the SOP method, the logic function of the integrated logic circuit is evaluated and simplified to the expression

images

Note that the logic expression is in a complemented form which ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

Digital Systems Design with FPGAs and CPLDs

Digital Systems Design with FPGAs and CPLDs

Ian Grout
Synthesis of Arithmetic Circuits: FPGA, ASIC and Embedded Systems

Synthesis of Arithmetic Circuits: FPGA, ASIC and Embedded Systems

Jean-Pierre Deschamps, Gery J.A. Bioul, Gustavo D. Sutter

Publisher Resources

ISBN: 9780470900550Purchase book