Measurement uncertainty of time-based and voltage-based wheatstone bridge readout circuits

We investigate the uncertainty of a time-based approach to read out Wheatstone bridge circuits and we compare it to the classical voltage-based approach. The time-based approach utilizes electrical discharge time when the resistive sensor is connected to a charged capacitor. We compare both approaches based on measurement uncertainty models. Analytical equations are given and calculated for two integrated circuits (IC), Acam PS09 (time-based) and Texas Instruments ADS1220 (voltage-based). Expected value and measurement uncertainty are derived for both IC and parameters sorted by effect size on measurement uncertainty. Both models yield a measurement uncertainty in the range of 0.01% for a relative resistance change r=1E-2.