Reliability in testing techniques for precision Zener diodes

A voltage measurement system is described which can measure at the 5 V to 8 V level with a resolution of 1 μV and a long term uncertainty of 3 p.p.m. A microcomputer controls the three stage measurement process incorporating the techniques of a metrology lab. Reliability of measurement is ensured by repeated measurements and by duplicated paths to trace the voltage being measured back to the standards