ABSTRACT
Compact layouts for basic logic gates (such as NOR gates) and small networks that are frequently used (such as flip-flops and a full adder) are designed by professional designers with time-consuming efforts and are stored in computer memories (i.e., magnetic disks). Each layout is called a
cell
and a collection of these layouts is called a
cell library
. Once a cell library is ready, any other designer can call up specific cells on the monitor of a computer. By arranging them and adding connections among them by the use of a mouse, the designer can make a layout of the entire logic network. When the layout is complete, photomasks are automatically prepared by computer. Such a design approach is called the
cell-library design approach
.
