Digital sampling setup for measurement of complex voltage ratio

This paper describes digital sampling setup for measurement of complex voltage ratio. It was originally designed for calibration of a phase angle of current shunts. However later it was successfully used for comparison of various impedance standards up to 100 Ω, calibration of buffer transfer and also comparison of inductive voltage dividers (IVD) in frequency range up to 40 kHz. Magnitude uncertainty is in order of μV/V for voltage ratios up to 1:10 and frequency up to 40 kHz and phase uncertainty below 1 μrad at 1 kHz (coverage interval 95 %).