TABLE OF CONTENTS J. Crowe
Barrie Hayes-Gill
This chapter describes the various design routes that can be used to implement a circuit design. The decision regarding which of these design routes to use depends upon the following issues:
When should the first prototype be ready?
How many units are needed?
What are the power requirements?
What is the budget for the product?
What are the physical size limitations?
How complex is the design (gate count, if known)?
What is the maximum frequency for the design?
What loads will the system be driving?
What other components are needed to complete your design?
What experience have you or your group had to date in the design of digital systems?
These are the questions that must be asked before starting any design. The aim of this chapter is to provide background to the various design routes that are available. Armed with this knowledge, the answers (where possible) to the above questions should allow the reader to decide which route to select or recommend.
The various design options are illustrated in Figure 13.1. As can be seen, the choice is either to use standard products or to enter the world of application-specific integrated circuits (ASICs). The "standard product" route is to choose one, or a mixture, of the logic families such as 74HCT, 74LS, 4000 series, etc. On the other hand, an ASIC is simply an IC customized by the designer for a specific application. Various ASIC...
