Accurate high-ohmic resistance measurement techniques up to 1 PΩ

An overview is presented on precision high-ohmic resistance measurements for values of 100 MΩ and above. The two main measurement techniques in this resistance range are discussed, the current integration technique and the adapted Wheatstone bridge. The quality of high-ohmic resistance standards, especially their time constants, temperature and voltage dependence, often is limiting the final uncertainty that can be reached. Still, expanded uncertainties (k = 2) of only a few parts in 10⁵ are achievable at the 1 TΩ level.