Chapter 12 - An Introduction to Voltage References

Abstract

This chapter provides an introduction to voltage references. Semiconductor voltage references are basic electronic building blocks that are used extensively in OEM circuit board designs, as well as integrated into the designs of many monolithic A/D and D/A converters, and voltage regulators. They are created by combining diodes and resistors with either the bipolar junction transistor (BJT) or the field-effect transistor (FET) and op amps. Various techniques for creating and optimizing voltage references are reviewed in this chapter. While most forms of current instrumentation use either voltage or current references, the former are far more readily available. Voltage references include discrete zener diodes, temperature-compensated zeners, as well as several different types of integrated circuit devices such as bandgap, buried zener, and many more. The chapter presents a voltage reference family tree and also discusses the advantages of voltage references. The advantages of using voltage references is their inherent constant voltage outputs, which (ideally) are independent of changes in supply voltage, temperature, load resistance, load current, or aging over time.