Current Sources and Voltage References

1

Chapter 1

A Short History of References

1.1 Introduction

Current sources and voltage references both depend on inherent characteristics of the

transistor, either the bipolar junction transistor (BJT) or the field-effect transistor (FET),

in order to operate properly. It seems only fitting then, in beginning this book, that we

first take a brief trip back in time, and trace a history of how and when some of these

products originated.

Actually, current sources and voltage references both predate the integrated circuit by

several decades. Current sources were originally created by simply using resistors or

by using resistors together with vacuum tubes. ...