A calibration method disclosed herein calibrates at least one of a capacitive load and a charging current controlling a charge-to-digital timer (CDT). In general, the disclosed calibration method measures multiple calibration phases based on start and stop signals separated by a known time difference, and therefore having a known phase, and adjusts at least one of the capacitive load and the charging current of the CDT based on the measured calibration phases. In so doing, the disclosed calibration method reduces power dissipation and peak supply currents over the frequency range of the CDT.