Development of a compact Zener DC voltage standard with detachable module system

We are developing a compact Zener voltage generating system as a secondary standard of DC voltage. The main unit of the system includes a temperature-controlled Zener diode module driven with a built-in battery. It is detachable from an expansion unit with larger battery packs for longer-time battery operation. This system realizes a compact DC voltage standard with maintaining state-of-the-art temporal stability and temperature stability performances of the output voltage. The results of the precise measurements based on a Josephson voltage standard show excellent drift characteristics within 2 ppm/year.