Error minimization in time-constant measurements

Time-constant measurements are often applied to determine parameters of exponential waves, and to find the value of capacitance or resistance in an
RC
circuit. The charging or discharging process is then monitored and the time distance, defined by two threshold levels, is precisely measured by means of a digital method. Analysis shows that proper choice of the thresholds can reduce a measurement error due to inaccuracy of threshold level calibration.