TABLE OF CONTENTS Here's what you're going to see in this chapter:
Why standardization is mandatory in digital layout
Advantages of standardization techniques in analog layout
Why we butt some cells together
Tips if you have few metals
Tips if you have lots of metals
Digging channels for our wires
When to run big power lines
Getting signals in and out of tight spots
How to guarantee a good fit between cells
How to guarantee rule-perfect layout
How to save time
How to protect your gates from zaps
In order for automated layout tools to be able to place and connect components, you need rules. Rules for the cells. Rules for placement. Rules for connectivity.
Think of plastic Lego bricks for a second. These uniform little play blocks all have connections in exactly the same places, spaced at predictable intervals. They all fit on that flat, square sheet of green plastic with gridded bumps that we all called the lawn or the garden.
The blocks all fit with each other. They all fit on the grid.
The reason Legos fit so well together is because the blocks are all standard length, standard width, standard height, with connection bumps in standard places. You cannot just throw any random block design into this process.
Cell libraries that are designed to be used with automated layout software follow guidelines and rules the same way as Lego...
