1.6 Summary

In this chapter we have looked at the difference between full-custom ASICs, semi-custom ASICs, and programmable ASICs. Table 1.3 summarizes their different features. ASICs use a library of predesigned and precharacterized logic cells. In fact, we could define an ASIC as a design style that uses a cell library rather than in terms of what an ASIC is or what an ASIC does.

You can think of ICs like pizza. A full-custom pizza is built from scratch. You can customize all the layers of a CBIC pizza, but from a predefined selection, and it takes a while to cook. An MGA pizza uses precooked crusts with fixed sizes and you choose only from a few different standard types on a menu. This makes MGA pizza a little faster to cook and a little cheaper. An FPGA is rather like a frozen pizza—you buy it at the supermarket in a limited selection of sizes and types, but you can put it in the microwave at home and it will be ready in a few minutes.

In each chapter we shall indicate the key concepts. In this chapter they are

• The difference between full-custom and semicustom ASICs
• The difference between standard-cell, gate-array, and programmable ASICs
• The ASIC design flow
• Design economics including part cost, NRE, and breakeven volume
• The contents and use of an ASIC cell library

Next, in Chapter 2, we shall take a closer look at the semicustom ASICs that were introduced in this chapter.