Noise investigation of a high precision digital multimeter model HP3457A or HP3458A for microvolt level dc voltage measurements

This article examines noise characteristics of a high precision digital mul timeter HP3457A or HP3458A by presenting a conceptual but useful model for the generation of zero voltage error under short-circuited input terminals. Two setting states, auto-zero on (AZ-ON) and off (AZ-OFF) are tested and o ne important conclusion derived is that the state of AZ-OFF has a more exte nsive potential of performing to the full specifications for measurements o f mu V level dc voltage than that of AZ-ON. (C) 1999 American Institute of Physics. [S0034-6748(99)04212-4].