Analytical Fit of the Transfer Function of a Logarithmic Electrometer and Correction for Ambient Temperature Variations
Raymond W. Huggins · Review of Scientific Instruments · 1973
An analytical fit has been derived for the transfer function of a logarithmic electrometer utilizing a p-n junction diode as a feedback loop element. Elementary semiconductor theory has been used to describe the diode current-voltage characteristic, and the diode ohmic resistance and an external parallel resistance have been included in the circuit analysis. A temperature correction has been applied to account for a difference in the temperature of the diode during calibration and during the taking of data. The analytical fit with temperature correction is believed to be accurate to better than 10% of the absolute current input over seven current decades.