TABLE OF CONTENTS Make a copy of the preceding schematic to place in front of you as you read along with this Case Study. Read through the Study once for general perspective. Read it again for analysis and better understanding. Read it again and again to increase your level of understanding and your internalization of these good practices. [1]
Enjoy.
Unlike Case Study 1, where we followed each step of an engineer's thought process as he builds his layout, in Case Study 2 we will dissect an already-completed layout. We will look at the various layout techniques used and discuss the ways this cell is put together.
We will illustrate how this layout can be improved, and improved again, depending on the level of demand of the circuit. This study will particularly help readers lay out RF circuits that have stringent requirements for matching and low parasitics.
Whereas Case Study 1 was entirely CMOS layout, this is a Bipolar layout. It is a high frequency Bipolar layout, in particular. This study is designed to give mask designers with primarily CMOS experience some exposure to the kinds of techniques you must use in higher frequency RFIC [2] problems.
We will discuss three examples that are all good, valuable, workable solutions for the layout. Depending on the requirements of the circuit, any one of these three layouts might be the best, most efficient design.
First we will dissect what I call a reasonable version. The reasonable version might...
