Precision nonlinear low current meter

Mobile measuring systems that allow small electric parameters to be estimated with high accuracy in real time are relevant for leading edge high-tech applications. In most cases, measurements are carried out with the use of piecewise linear scales and corresponding linear analog-to-digital converters. This technology does not meet the requirements of high measurement accuracy due to errors in the automatic switching of the measuring scale when an input signal varies in a wide range, for example, 100 dB. A new method for measuring small electric parameters based on a nonlinear scale is proposed. The nonlinear analog-to-digital meter having been developed and tested is described. An exponential function with an index m < 1 is used as a scale. The results of measuring nanoampere currents ranging between 1 nA and 1 µA, obtained with the help of the meter model, are presented.