High end multimeter voltage reference question

[Bootalito]

How does a 32bit adc accept a ~7.2V buried zener reference? Is there just a 4:1 precision voltage dividor to get it down to ~2.5V then just software calibrated out? Or   do high end multimeters accept a 7.2V reference natively?

[Andreas]

Hello,

high end multimeters do not have a 32 Bit ADC.
They usually have a multi-slope ADC. (around 24-28 Bit resolution)
If you look e.g. at the 34401A service guide you will find that they generate a +/-10V reference out of the 7V by a precision resistor network.

with best regards

Andreas