TABLE OF CONTENTS The zener diode was the first discrete semiconductor device to be used as a basic voltage reference. It was created in the late 1950s by its inventor Clarence Zener, a Westinghouse researcher. Ever since it became commercially available in the early 1960s, the zener diode has been a popular workhorse in countless industrial and commercial designs worldwide, because of its simplicity, reasonable accuracy, small size, and low cost. Besides providing a simple means of voltage reference, the zener diode is also used for biasing, stabilization, switching, and clamping. Before the arrival of the integrated circuit reference voltage, the zener diode was the only affordable means for designers to create an on-board voltage reference. During the 1960s, engineers began creating small linear regulators and references by combining zeners with BJTs. They also discovered that by characterizing and selecting zeners, and adding one or more series rectifier diodes, they could create temperature-compensated zener references. By the late 1960s, the small glass package zener had been scaled up to provide a power zener, often available in a metal stud package. (In some industrial applications where higher voltages and currents are involved, power zeners are still the only option.) When the silicon bipolar IC became available in the early 1970s, designers began to use the op amp to buffer and amplify the temperature-compensated zener diode, to provide a more stable reference. Figure 13.1 shows the complete zener diode family tree.
After the op amp was...
