The ultra-Zener- a portable replacement for the Western cell?

Abstract

Twenty-four samples of the Ultra-Zener, an integrated circuit containing a buried Zener junction, type no. LTZ 1000, have been tested since March 1988. With some circuit modification, half of the samples have been found to have an aging rate of less than 1.5 p.p.m./year, and all have an aging rate of less than 4 p.p.m./year. The initial tests indicate that the Ultra-Zener seems to have no serious disadvantages as a voltage standard apart from price and some added circuit complexity. >