Current Sources and Voltage References

vii

Contents

List of Figures and Photos xiii

List of Tables xxv

Acknowledgements xxix

1. A Short History of References 1

1.1 Introduction 1

1.2 The first JFETs and op amps 3

1.3 The first bandgaps 5

1.4 The buried-zener debuts 7

1.5 Advancements in technology 8

1.6 Other topologies emerge 9

2. An Introduction to Current Sources 13

2.1 An overview 13

2.2 Precision resistors, networks, and trimmers 21

2.3 Essential development equipment 29

2.3.1 Bench power supply unit 29

2.3.2 A thermostatically controlled oven 30

2.3.3 A calibrated, precision ammeter 30

3. The P-N Junction 31

3.1 Characteristics of the P-N junction 31

4. Using BJTs to Create Current ...