Making precision measurements of zener diode voltages

ZENER DIODES have come into wide use in the last few years as working standards of electromotive force (emf) for many applications. They have been used to replace standard cells in recording and controlling equipment and are, in some cases, being used as a standard at the 0.01% level. Interest is also being shown in their use as a reference standard of emf at the 0.001 and 0.0001% levels.