NOISE MARGIN CRITERIA FOR DIGITAL LOGIC-CIRCUITS

The concept of noise margin is very important in the design and application of digital logic circuits. Most engineers realize that is it in some way related to the transfer characteristics of inverter circuits and most textbooks have some discussion of noise margin as related to different logic families. However, most textbook descriptions of noise margin are very incomplete and in many cases both contradictory and misleading. This discussion reviews the noise margin issue, discusses many different criteria which have been used to characterize logic gates and discusses the standard treatments of noise margin in typical textbooks. Finally, a noise margin criteria is proposed as a replacement for the standard textbook approaches.